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AL  8 


The  late  Professor  E.  A.  Minchin,  M.A.,  F.R.S. 


Frontispiece] 


[See  page  669 


THE     JOURNAL 


OF   THE 


(fyukttk 

Microscopical   Club 


EDITED   BY 
A.    W.    SHEPPARD,    F.Z.S.,    F.R.M.S. 


SECOND     SERIES. 

VOLUME   XII. 


1913-1915. 


.»»»»--».._ 


••...•••• 


[Published  for  the  Club] 

WILLIAMS     AND     NORGATE, 

14.    Henrietta    Street,    Covent    Garden.     London, 
and  7,   Broad  Street,  Oxford. 


PRINTED   BY 
HAZELL,   WATSON   AND   VIXEY,   LD., 
LONDON'   AND   AYLESBURY. 


Ill 


C  O  N  T  E  N  T  S . 


PART    No.    72.    APRIL    1913. 


Papers. 

E.  Heron-Allen.  F.L.S.,  F.R.M.S.,  awl  A.  Euiland,  F.R.M.S. 
The  Foraminifera  in  their  Role  as  World- builders :  A 
Review  of  the  Foraminiferous  Liiw  stones  and  Other  Rocks 
of  th^  Eastern  and  Western  Hemispheres  (Plates  1-3) 

W.  M.  Bale,  F.R.M.S.     Notes  on  Some  of  the  Discoid  Diatoms   . 

Henry  Whitehead,  B.Sc.  Some  Notes  on  British  Freshwater 
Rhabdocoelida — a  Group  of  Turbellaria  (Plate  4) 

Charles  F.  Rousselet,  F.R.M.S.  The  Rotifera  of  Devils  Lake, 
with  Description  of  a  New  Brachionus  (Plates  5  and  (3) 

Arthur  Dendy,  D.Sc,  F.R.S.  President's  Address— By- Pro- 
ducts of  Organic  Evolution  (Plate  7)    . 

David  Bryce.  On  Five  New  Species  of  Bdelloid  Rotifera  (Plates 
8  and  9)      ........ 

Notes. 

E.  M.  Nelson,  F.R.M.S.     A  New  Low-power  Condenser 

E.  M.  Nelson.  F.R.M.S.     Xavicula  rhomboides  and  Allied  Forms 

E.  M.  Nelson,  F.R.M.S.     On  Microscope  Construction  and  the 

Side  Screw  Fine  Adjustment  (Figs.    1   and  2  in  text) 
E.  M.  Nelson,  F.R.M.S.     Note  on  Pleurosiqma  angukitum  (Figs. 

3  and  4  in  text)    ........ 

E.  M.  Nelson,  F.R.M.S.     Actinoci/clus  Ralfsii  and  a  Coloured 

Coma  ....  ..... 

Notices  or  Books         ........ 


PAGH 


1 

17 
4.3 
57 
05 

83 


95 
90 

90 

98 

100 
101 


Proceedings,  etc. 

Proceedings  from  October  22nd,   1912,   to  February  25th,   1913, 
inclusive       ......... 

Forty-seventh  Annual  Report,    1912  r 

Report  of  the  Treasurer.    1912  . 


103 
113 

120 


PART    No.    73,    NOVEMBER    1913. 

Papers. 

E.  Heron-Allen,  F.L.S.,  F.G.S.,  F.R.M.S.,  and  A.  Earland, 
F.R.M.S.  On  some  Foraminifera  from  the  North  Sea, 
dredged  by  the  Fisheries  Cruiser  "  Huxley  "  (International 
North  Sea  Investigations — England)  (Plates  10  and  11)  . 


12 1 


'\J 


■     ■- 


IV  CONTENTS. 

PACK 

C.  D.  Soar,  F.L.S.,  F.R.M.S.  Description  of  Arrhenurus  Scour- 
fieldi  and  Acercus  longitarsus,  Two  New  Species  of  Water- 
mites  (Plates   12  and   13) 130 

G.  T.  Harris.     The  Collection  and  Preservation  of  the  Hydroida      143 

T.  A.  O'Donohoe.  The  Minute  Structure  of  Coscinodiscus 
asteromphalus  and  of  the  Two  Species  of  Pleurosigma, 
P.   angulatum  and  P.  balticum       .  .  .  .  .155 

Henry  Sidebottom.     Lagenae  of  the  South-West  Pacific  Ocean 

(Supplementary  Paper).      (Plates  15-18)  .  .  .101 

James  Murray,  F.R.S.E.     Gastrotricha  (Plate  19)  .  .      211 

Notes. 

Edward  M.  Nelson,  F.R.M.S.      On  a  New  Method  of  Measuring 

the  Magnifying  Power  of  a  Microscope  .  .  ,239 

Proceedings,  etc. 

Proceedings  from  March  25th,   1913,  to  June  24th,    1913  .      245 

Obituary  Notice  :   Rt.  Hon.  Sir  Ford  North,  F.R.S.,  F.R.M.S.   .      258 

PART    No.    74.    APRIL    1914. 
Papers. 

Arthur  Dendy,  D.Sc,  F.R.S.     President's  Address — Organisms 

and  Origins  ........      259 

S.  C.  Akehurst,  F.R.M.S.     A  Changer  for  Use  with  Sub-stage 

Condensers  (Figs.    1   and  2)  .  .  .  .  .  .277 

S.  C.  Akehurst,  F.R.M.S.  A  Trap  for  Free-swimming  Or- 
ganisms (Fig.  3)  .  .  .  .  .  .  .  .      279 

E.  M.   Nelson,   F.R.M.S.      An  Improved   Form   of  Cheshire's 

Apertometer  (Fig.   4)    .  .  .  .  .  .  .281 

F.  J.  Cheshire,  F.R.M.S.     Two  Simple  Apertometers  for  Dry 

Lenses  (Figs.   5  and  6)  .....  .      283 

M.  A.  Ainslie,  R.N..  B.A.,  F.R.A.S.     A  Variation  of  Cheshire's 

Apertometer  (Figs.   7  and  8)  .  .  .  .  .      287 

James  Burton.     On  the  Disc-like  Termination  of  the  Flagellum 

of  some  Euglenae  .  .  .  .  .  .  29 J 

E.  M.  Nelson,  F.R.M.S.     On  the  Measurement   of  the  Initial 

Magnifying  Powers  of  Objectives  (Fig.   9)       .  .  .      295 

S.  C.  Akehurst,  F.R.M.S.  Some  Observations  concerning  Sub- 
stage  Illumination  (Plates  20-22)  .  .  .  .301 
T.   A.   O'Donohoe.      An  Attempt  to  Resolve  and  Photograph 

Pinnularia  nobilis         .......      309 

N.  E.  Brown,  A.L.S.      Some  Notes  on  the  Structure  of  Diatoms 

(Plate  23) 317. 

Notes. 

James  Burton.     On  a  Method  of  Marking  a  Given  Object  for 

Future  Reference  on  a  Mounted  Slide.  .  .  .311 


CONTENTS.  V 

Vk  v. 
}).  M.  DRAPER.     A  Live  Box  for  the  Observation  of  Insects  and 

Similar  Objects    ........  313 

15.  M.  Draper.     Dark-ground  Illumination   with  the  Greenough 

Binocular     ......•••  313 

E.  M.  Nelson.  F.R.M.S.     Amphvpleura  Lindheimeri         .  .  315 

Notices  of  Books         ........  339 

Proceedings,  etc. 

Proceedings   from  October  2Sth,   1013,  to  February   24th.   1914. 

inclusive       .........      340 

Forty-eighth  Annual  Report,    1913 314 

Report  of  the  Treasurer,    1913 302 

List  of  Members  .  ......        i — xxxii 

PART    No.    75.    NOVEMBER    1914. 

Papers. 

Edward  M.  Nelson.  F.R.M.S.     A  New  Object  Glass  by  Zeiss. 

and  a  New  Method  of  Illumination  (Figs.  1-3)  .  .  .  3 

Edward  M.  Nelson.  F.R.M.S.     A  New  Low-power  Condenser 

(Fig.  4) 367 

Edward  M.  Nelsox.  F.R.M.S.      Binocular  Microscopes  (Fig.  5)  .      309 

A.  E.  Hilton.   Notes  on  the  Cultivation  of  Plasmodia  of  Badhamia 

utricularis  (Fig.   0)        ......  381 

A.  A.  C.  Eliot  Merlin,  F.R.M.S.     On  the  Minimum  Visible       .      385 

C.  F.  Rousselet,  F.R.M.S.     Remarks  on  Two  Species  of  African 

Volvox 393 

C.  F.  Rousselet,  F.R.M.S.  Report  on  the  Conference  of  Dele- 
gates of  Corresponding  Societies  (British  Association)  held 
at  Havre      .........      395 

( '.  F.  Rousselet,  F.R.M.S.     Pedalion  ou  Pedalia  ;    une  question 

de  nomenclature  dans  la  classe  des  Rotiferes    .  .  .397 

Proceedings,  etc. 

Additions  to  the  Library  since  January  1914  .  .  .  399 

Additions  to  the  Club  Cabinet  since  October   1912       ...  .  401 

Proceedings  from  March  24th  to  June  23rd.    1914,   inclusive    .  411 

Obituary  Notice  :    Dr.  M.   C.   Cooke 422 

Table  for  the  Conversion  of  English  and  Metrical  Measures   .  .  424 

PART    No.    76,    APRIL    1915. 

Papers. 

R.    T.    Lewis.    F.R.M.S.     The   Early  History   of   the   Quekett 

Microscopical  Club        .  .  .  .  .  .  42  ~> 

D.  J.  Scourfield.  F.Z.S.,  F.R.M.S.     A  New  Copepod  found  in 

Water  from  Hollows  on  Tree  Trunks.      (Plates  24  and  25)     431 


VI  CONTENTS. 


PAGE 


E.  A.  Minchin,  M.A.,  F.R.S.     Some  Details  in  the  Anatomy  of  the 

Rat  Flea  (Ceratophyllus  fasciatus).     (Plates  26-32)  .  .441 

Arthur  Dendy,  D.Sc.,  F.R.S.  President's  Address.  The  Bio- 
logical Conception  of  Individuality        ....      465 

W.  Williamson,  F.R.S.E.,  and  Charles  D.  Soar.  F.L.S., 
F.R.M.S.  British  Hydracarina  :  The  Genus  Lebertia. 
(Plates  33  and  34) 479 

J.  W.  Gordon.     A  "  New  "  Object  Glass  by  Zeiss  (Figs.  1  and  2)     515 

G.  T.  Harris.     Microscopical  Methods  in  Bryological  Work        .      52  ! 

Proceedings,  etc. 

Proceedings  from  October  27th,   1914,  to  February  23rd,   1915, 

inclusive       .  .  .  .  .  .  .  .  .537 

Forty- ninth  Annual  Report,   1914  .  .  .  .  .  .551 

Report  of  the  Treasurer,    1914         .  .  .  .  .  .      558 

Obituary  Notice  :  F.  W.   Millett,   F.G.S.,  F.R.M.S.  .  .  .      559 

PART    No.    77,    NOVEMBER    1915. 

Papers. 

M.  A.  Ainslie,  R.N.,  B.A.,  F.R.A.S.     An  Addition  to  the  Ob- 
jective (Figs.    1   and  2)  .....  561 
A.  A.  C.  Eliot  Merlin,  F.R.M.S.     Notes  on  Diatom  Structure  .       577 
G.  T.  Harris.     A  Note  on  the  Slides  of  Fissidentaceae  in  the 

Q.M.C.  Cabinet 581 

A.  E.  Hilton.     Further  Notes  on  the  Cultivation  of  Plasmodia 

of  Badhamia  utricularis         ......      585 

James  Burton.     Hydrodictyon  reticulation       ....      587 

E.  M.  Nelson,  F.R.M.S.     Various  Insect  Structures  .  .  .      593 

J.  W.  Evans,  D.Sc,  LL.B.  (London).  The  Determination  of 
Minerals  under  the  Microscope  by  means  of  their  Optical 

Characters  (Plates  35-37) 597 

David  Bryce.     On  Five  New  Species  of  the  Genus  Habrotrocha 

(Plates  38  and  39) 631 

Notices  of  Books  (Plate  40)         ......      643 

Proceedings,  etc. 

The  Club  Cabinet,  Additions  to  .  .  .  .  .646 

Proceedings  from  March  23rd  to  June  22nd,  inclusive    .  .      653 

Obituary  Notice  :   E.   A.  Minchin,  M.A.,  F.R.S.   (Portrait)  .      669 

Index  to  Volume  XII.         .  .  .  .  .  .  .      673 


Vll 


LIST    OF    ILLUSTRATIONS. 


PLATES. 

Portrait  of  the  late  Prof.  E.  A.  Minchin.  M.A.,  F.R.S.,  Facing  page  501 

1-3.   Foraminiferal  Limestones. 

4.  Rhabdocoelida. 

5.  Asplanchna  Silvestrii  Daday. 

6.  Rotifera. 

7.  Spicules  of  Tetraxonid  Sponges. 

8,   9.  New  Species  of  Bdelloid  Rotifera. 

10.  Foraminifera  from  the  North  Sea. 

11.  Cornuspira  diffusa  Heron- Allen  and   Earland.      Sand  Grains, 

etc.,  from  the  Bottom  Deposits. 

12.  <$  Arrhenurus  Scour fieldi  sp.  nov. 

13.  q  Acercus  longitarsus  sp.  nov. 

14.  Structure  of  Pleurosigma  bait  ten  m. 

15-18.   Lagenae  of  the  South-West  Pacific  Ocean. 

19.  Gastrotricha. 

20.  View  of  Back  Lens  of  Objective  with  P.  angulatum  in  focus. 
21,  22.  Resolution  with  Annular  Illumination. 

23.   Structure  of  Diatoms. 
24,  25.   Moraria  arboricola  sp.   nov. 
26-32.  Anatomy  of  the  Rat  Flea. 
33,  34.  The  Genus  Lebertia. 
35-37.   Examination  of  Minerals. 
38,  39.  Xew  Species  of  Habrotrocha. 

40.   Rhizopoda. 

FIGURES   IN   THE    TEXT. 

Page     98.   Side-screw  fine  adjustment. 
,,         99.  Upper  and  lower  membranes  in  P.  strigusum  and  P.  balti- 

cum. 
„      277.  A  changer  for  sub-stage  condensers. 

,,      280.  A  trap  for  free- swimming  organisms. 

,,       281.   An  improved  form  of  Cheshire's  Apertometer. 

,,       285.  Two  simple  apertometers  for  dry  lenses. 


VJ11  LIST    OF    ILLUSTRATIONS. 

Page  288.  A  variation  of  Cheshire's  Apertometer. 
-j8J.  ,,  ,,  ,, 

298.  The  measurement  of  the  initial  magnifying  power  :  diagram 

to  show  relative  position  of  apparatus. 
32Q.  Structure  of  pores  in  P.  balticum  according  to  O.  Miiller. 
365.  Diagram  showing  method  of  illumination. 

oOO.  ,,  ,,  ,,  ,, 

3C8.  Centring  stop-holder. 

374.  Diagram  of  eye  and  Ram~den  disc. 

383.   Exhibition  of  plasmodia. 

517.   Diagram  illustrating  a   "  new  "   object-glass. 

"10'  »J  »?  ?»  »> 

567.   An  addition  to  the  objective  :    diagram. 
504.   Various  insect  structures. 


-3 


THE  JOURNAL  :      V 

OF   THE 

<®iuhcii    $$t c rose  opt cal    dDInIr« 

THE  FORAMINIFERA  IN  THEIR  ROLE  AS  WORLD- 
BUILDERS:  A  REVIEW  OF  THE  FORAMINIFEROUS 
LIMESTONES  AND  OTHER  ROCKS  OF  THE 
EASTERN   AND   WESTERN    HEMISPHERES. 

By  Edward  Heron-Allen,  F.L.S.,  F.R.M.S.,  axd 
Arthur  Earland,  F.R.M.S. 

{Read  October  22nd,  1912.) 

Plates  1-3. 

"  Life ,  as  we  call  it,  is  nothing  but  the  edge  of  the  boundless   Ocean  of 
Existence   where    it   comes    on   Soundings." — 0.    W.   Holmes,    The   Pro- 
fessor, V. 

Our  late  President,  Prof.  E.  A.  Minchin,  F.R.S.,  in  his  last 
Presidential  Address  *  dealt  with  certain  organisms  which  he 
regarded  as  the  simplest  existing  living  structures,  and  speculated 
on  the  Origin  of  Life  in  this  planet.  Subsequently  at  the  British 
Association  Meeting  at  Dundee  he  led  a  most  interesting  dis- 
cussion on  the  same  subject,  a  discussion  which  left  those  who 
had  the  privilege  of  listening  to  it  convinced  of  one  fact  at  least, 
viz.  that  no  two  of  the  eminent  men  who  took  part  in  the  debate 
were  agreed  on  any  single  point.  But  as  the  earliest  forms 
of  life  were  necessarily  of  such  a  simple  nature  that  they  could 
oy  no  possibility  have  been  preserved  as  fossils,  the  interest 
of  geologists  may  almost  be  said  to  commence  with  the  stage 
in  which  life  had  become  endowed  with  a  sufficiently  complex 
structure  to  leave  recognisable  remains  in  the  geological  record. 

The  Foraminifera  would  seem  to  constitute  such  a  group.  Of 
extremely  simple  structure,  mere  protoplasm  without  differenti- 
ation other  than  the  nucleus,  they  yet  possess  the  power  either 
of  secreting  a  solid  shell  from  the  mineral  salts  absorbed  from 

*  Journ.  Q.M.C.,  Ser.  2,  Vol.  XI.  p.  339. 
Jourx.  Q.  M.  C,  Series  II.— No.  72.  1 


*) 


E.    IIIRON-ALLEN   AND    A.    EARLAND    ON    THE    FORAMINIFERA 


their  surrounding  medium,  or'of  building  up  adventitious  shells 
by  the  co-ordination  of  foreign  material  obtained  from  their 
immediate  environment.  These  shells,  from  their  minute  size 
and  composition,  are  peculiarly  adapted  for  preservation  as 
fossils. 

Hence,  whatever  the  origin  of  life  may  have  been,  we  might 
reasonably  expect  that  among  its  earliest  records  would  occur 
Foraminifera  of  simple  and  ancestral  types,  and  that  subsequent 
geological  periods  would  show  a  constant  progression  in  their 
development.  Such,  however,  is  not  the  case.  So  far  as  our 
geological  knowledge  carries  us  at  present,  the  Foraminifera 
make  their  first  appearance  in  the  rocks  in  a  highly  differentiated 
stage,  and  among  the  earliest  recognisable  groups  are  many  species- 
which  are  still  existing  and  dominant  types  to-day. 

It  is  not  so  very  many  years,  less  than  half  a  century  in  fact, 
since  the  sensational  discovery  of  Eozoon  Canadense  (1)  (2)  (3)  in 
the  Laurentian  rocks  of  Canada  was  hailed  as  evidence  that  the 
oldest  fossil  was,  as  might  have  been  expected,  a  rhizopod.  Into 
the  long  warfare  which  was  waged  round  this  fossil,  in  which  the 
late  Prof.  K.  Mobius  took  an  active  part  (22),  it  is  not  proposed 
to  enter  in  detail.  But  there  was  at  the  time  of  its  discovery 
no  greater  authority  on  the  Rhizopoda  than  the  late  Dr.  W.  B. 
Carpenter,  a  former  President  of  this  Club.  He  threw  the  whole 
weight  of  his  authority  into  the  scale  in  favour  of  the  foramini- 
feral  nature  of  Eozoon,  and  to  the  last  was  convinced  of  the 
soundness  of  his  belief.  But  the  balance  of  evidence  has  turned 
against  him,  and  since  his  death  but  little  interest  has  been 
shown  in  the  question,  Eozoon  having  been  relegated  by  more  or 
less  general  consent  to  the  mineral  kingdom. 

We  are,  however,  again  threatened  with  a  renewal  of  the 
controversy,  for  Mr.  It.  Kirkpatrick,  of  the  British  Museum, 
has  recently  announced  in  Nature  that  he  is  in  possession  of 
fresh  evidence  of  the  foraminiferal  nature  of  Eozoon,  and  will 
shortly  publish  it.  The  microscopical  world  will  no  doubt  await 
this  evidence  with  interest,  not  unmixed,  perhaps,  with  some 
trepidation  at  the  reopening  of  this  chose  jugee.  From  the  point 
of  view  of  the  subject  of  our  paper,  viz.  "  The  Foraminifera  as 
World-builders,"  definite  proof  of  the  rhizopodal  nature  of 
Eozoon  would  be  very  welcome.  Eozoon,  whatever  its  nature 
may  be,  occurs  in  enormous  reefs  in  the  Laurentian   rocks   of 


IN    THEIR    ROLE    AS    WORLD-BUILDERS.  3 

Canada  and  elsewhere,  and  we  should  thus  have  evidence  that 
even  at  this  early  stage  of  the  world's  history,  the  Foraminifera 
had  commenced  to  play  that  important  part  in  the  formation 
of  strata  which  they  have  continued  in  nearly  all  the  successive 
periods  of  geological  history,  and  which  is  still  proceeding  in 
the  deep  sea  to-day.  It  is  no  exaggeration  to  say  that,  in 
spite  of  their  diminutive  size,  the  Foraminifera  have  played, 
and  are  still  playing,  a  greater  part  in  building  up  the  crust 
of  the   earth   than   all    other  organisms  combined. 

Dismissing  Eozoon  for  the  present  as  incertae  sedis,  we  find 
that  the  only  other  pre-Cambrian  records  which  can  be  associated 
with  Foraminifera  are  the  peculiar  bodies  described  by  Cayeux  (4) 
from  certain  quartzites  and  pthanites  of  the  pre-Cambrian  strata 
of  Brittany.  These  are,  however,  of  such  minute  size  compared 
with  other  Foraminifera  that  their  nature  cannot  be  accepted 
on  the  evidence  hitherto  available. 

It  appears,  therefore,  that  at  present  we  have  no  unquestionable 
records  of  Foraminifera  in  pre-Cambrian  rocks ;  but  it  is  quite 
possible  that  such  discoveries  may  be  made  in  the  future,  as  fossils 
of  a  higher  type  have  been  found,  and  it  seems  unlikely  that 
Foraminifera  did  not,  or  could  not,  exist  in  seas  capable  of 
supporting  such  higher  forms  of  life. 

When,  however,  we  come  to  the  Cambrian  strata  we  find  the 
Foraminifera  flourishing,  and  already  marked  by  numerous  widely 
separated  types.  So  long  ago  as  1858  Ehrenberg  (5)  figured 
some  internal  glauconitic  casts  of  Foraminifera  from  a  clay  near 
St.  Petersburg,  which  is  known  to  be  of  Lower  Cambrian  age. 
According  to  Chapman  (9)  these  casts  are  referable  to  at  least 
five  genera,  viz.  Verneuilina  and  Bolivina  (family  Textularidae), 
Nodosaria  (family  Lagenidae),  Pidvinulina  and  Rotalia  (family 
Rotalidae). 

Now  it  is  noteworthy  that  none  of  these  genera  are  of  simple 
or  primitive  types,  but  are  all  comparatively  complex  in  the 
arrangement  of  their  chambers,  and  representing  three  distinct 
types  of  construction.  Hence  in  this  earliest  geological  record 
we  find  the  group  already  well  established,  and  markedly 
differentiated  in  structure.  No  monothalamous  or  primitive 
type  appears  in  this  earliest  list,  although  we  may  be  sure 
that  they  must  have  been  in  existence,  both  then  and  during 
antecedent  ages. 


4         E     HERON-ALLEN    AND    A.    EARLAND    ON    THE    FORAMTNIFERA 

Since  the  time  of  Ehrenberg  there  have  been  other  discoveries 
of  Cambrian  Foraminifera  in  America  (6)  (7)  and  Siberia  (8). 
We  have  not  had  an  opportunity  of  seeing  either  of  these  reports, 
but  it  may  be  noted  that  the  New  Brunswick  rocks  furnished 
representatives  of  the  pelagic  genera  Orbulina  and  Globigerina 
(family  Globigerinidae),  while  the  Siberian  rock  is  described  as 
•assuming  an  oolitic  structure  on  account  of  the  numerous  Fora- 
minifera which  it  contains.  It  is  therefore  apparent  that  the 
Foraminifera  had  already  assumed  that  dominant  position  which 
they  have  ever  since  maintained  in  the  biology  of  the  sea. 

Turning  to  our  own  country,  the  oldest  Foraminifera  yet 
recorded  are  those  described  by  Chapman  (9)  from  a  limestone 
of  Upper  Cambrian  age  near  Malvern  (PI.  1,  fig.  1).  This  record  is 
'of  great  interest  because  all  the  Foraminifera  described  are  either 
monothalamous  (genera  Lagena,  SpiriUina)  or  polythalamous 
shells  of  simple  type  (genera  Nodosaria,  Marginulina,  Cristel- 
laria).  As  will  be  seen  from  the  rock  section  figured  by  Chapman, 
the  Foraminifera  of  one  genus,  SpiriUina,  form  a  considerable 
proportion  of  the  entire  mass  of  the  rock  (PI.  1,  fig.  1).  The  other 
species  described  are  stated  to  have  been  of  very  rare  occurrence. 
Now  SpiriUina  is  one  of  the  simplest  conceivable  types  of  rhizo- 
podal  shell  structure,  an  undivided  tube  coiled  on  itself  in  one  plane, 
iand  is  theoretically  one  of  the  forms  which  might  be  expected 
to  turn  up  in  the  earliest  records.  Chapman  has  on  certain 
minor  points  of  structure  instituted  a  new  species  {SpiriUina 
«Groomii  Chapman)  for  this  Cambrian  type,  but  it  appears  to 
be  nothing  more  than  a  variety  of  SpiriUina  vivipara  Ehrenberg, 
a  species  which  at  the  present  day  occurs  on  muddy  bottoms 
of  moderate  depth  in  all  parts  of  the  world.*  So  far  as  we 
are  aware,  however,  there  is  no  other  record  of  its  occurrence 
in  sufficient  abundance  to  form  a  noticeable  constituent  of  any 
deposit,  recent  or  fossil.  In  recent  dredgings  it  cannot  be 
described  as  an  abundant  species. 

In  the  next  period,  the  Silurian,  there  are  many  records  (10) 
(11)  (12)  (13)  of  Foraminifera,  but  they  do  not  appear  to  be 
numerous.     Brady  (12)  records  and  figures  four  species  of   the 

*  Since  this  was  written  specimens  resembling  SpiriUina  Groomii  (Chap- 
man) have  been  found  in  dredgings  made  in  Blacksod  Bay,  Co.  Mayo,  and 
also  in  the  Moray  Firth.  They  will  be  described  and  figured  in  the 
forthcoming  report  on  the  Foraminifera  of  the  Clare  Island  Survey. 


IN    THEIR    ROLE    AS    WORLD-BUILDERS.  5> 

simple  type  Lagena,  which  are  still  existing,  and  of  world-wide 
distribution.  These  and  the  Spirillina  Groomii  of  Chapman 
(=  S.  vivipara  Ehrenberg)  are  therefore  probably  the  oldest 
living  types  now  in  existence. 

Of  greater  interest  is  the  recording  by  Chapman  (14)  and 
Vine  (15)  of  two  genera  of  arenaceous  Foraminifera,  viz.  Hyperam- 
mina  and  Stacheia  from  rocks  of  the  Wenlock  series.  These 
constitute,  so  far  as  we  are  aware,  the  earliest  evidence  of  the 
existence  of  arenaceous  Foraminifera.  The  geological  record 
does  not  furnish  any  evidence  in  support  of  the  theory,  so  fre- 
quently postulated,  that  the  earliest  Foraminifera  were  types 
Avith  adventitiously  constructed  tests  \  nor  do  we  see  any  reason 
for  accepting  this  theory.  The  property  of  secreting  mineral 
salts  from  the  surrounding  medium  is  common  to  organisms  of 
all  grades,  whereas  the  power  of  selecting  and  utilising  foreign 
material  seems  to  indicate  a  later  and  higher  stage  of  develop- 
ment. There  appears  to  be  no  geological  reason  why  the 
composite  tests  of  arenaceous  Foraminifera  should  have  escaped 
fossilisation,  when  the  delicate  shells  of  -calcareous  genera  were 
preserved,  had  the  two  groups  been  in  existence  together  in  pre- 
Silurian  times. 

The  Devonian  period,  according  to  Chapman  (16),  presents 
but  a  single  record  of  Foraminifera,  viz.  those  discovered  by 
Terquem  (13)  at  Paffrath  in  the  Eiffel.  Chapman  comments 
on  the  singular  absence  of  Foraminifera  in  the  Devonian  seas, 
where  the  conditions  for  their  existence  appear  to  have  been 
favourable. 

With  the  next  period,  however,  the  Carboniferous,  the  Fora- 
minifera first  begin  to  justify  the  title  of  our  paper  as  Worldr 
builders.  Various  genera  make  their  appearance  in  such 
numbers  as  to  form  enormous  deposits.  In  the  lower  Carbonif- 
erous strata  the  large  arenaceous  species  known  as  Saccammina 
fusuliniformis  (McCoy)  =  S.  Carteri  (Brady)  (17)  is  the  principal 
constituent  of  enormous  areas  of  limestone  in  Great  Britain  and  on 
the  Continent  (PI.  1,  fig.  2).  The  upper  Carboniferous  limestone, 
on  the  other  hand,  is  in  most  regions  of  the  world  largely  built  up 
of  the  shells  of  Fusulina,  a  perforate  foraminifer  belonging  to 
the  family  Nummulinidae.  Other  genera  which  are  largely 
concerned;  in  the  formation  of  Carboniferous  limestones  are 
'Endothyra\i^\.  1,  fig.  '6)  and  Archaediscus,  while  in  this  period 


6         E.    HERON-ALLEN    AND    A.    EARLAND    ON    THE    FORAMINIFERA 

occur  the  first  records  of  two  genera,  Amphistegi?ia  and  Nura- 
mulites,  which  in  later  times  were  destined  to  play  an  important 
part  in  the  formation  of  the  world's  crust. 

The  Permian  and  Permo-Carboniferous  rocks  show  a  decline 
in  the  importance  of  the  Foraminifera.  Perhaps  it  would  be 
more  correct  to  say  that  there  is  a  falling  off  in  the  records  of 
those  large  and  dominant  types  which  marked  the  Carboniferous 
period.  Foraminifera  of  many  different  genera  occur  in  the 
Permo-Carboniferous  rocks,  but  they  are  usually  of  compara- 
tively small  size,  and  so  do  not  readily  form  a  basis  for  rock 
formation.  But  in  New  South  Wales  and  Tasmania,  Nubecularia, 
which  is  the  lowest  type  of  imperforate  foraminifer,  forms  a 
principal  constituent  of  some  limestones  (18)  (PL  1,  fig.  4). 

TheTrias  yields  no  strata  in  which  Foraminifera  are  the  principal 
constituent.  Foraminifera  occur  in  many  horizons,  but  do  not 
constitute  any  large  proportion  of  the  fauna.  Perhaps  the 
richest  deposit  is  that  described  by  Chapman  (19)  from  Wedmore 
in  Somerset. 

Similarly  in  the  Jurassic  period,  the  Foraminifera,  although 
often  varied  and  abundant,  are  not  responsible  for  any  important 
proportion  of  the  whole  bulk  of  the  formation.  They  are  often 
confined  to  limited  zones,  in  which  they  occur  in  great  abundance, 
but  the  species  are  nearly  all  minute  and  completely  masked  as 
to  external  appearance  by  other  material.  The  most  important 
feature  of  this  period,  however,  is  the  sudden  bursting  into  active 
existence  of  numerous  hyaline  types,  principally  Lagenidae, 
hitherto  more  or  less  unknown.  They  occur  in  the  clays  of  the 
Lias  of  the  Continent  in  enormous  variety,  passing  insensibly 
from  one  species  into  another,  and  the  meticulous  precision  of 
Terquem  and  others  who  have  monographed  these  strata  has 
embarrassed  the  rhizopodist  with  a  wealth  of  synonyms. 

Up  to  this  period  the  arenaceous  Foraminifera  have  not  presented 
any  great  diversity  of  forms,  although,  as  we  have  seen,  certain 
genera  (Saccammina,  Endothyra,  etc.),  have  played  an  important 
part  in  building  up  strata.  But  Haeusler  (20)  (21)  has  de- 
scribed a  most  interesting  series  of  arenaceous  types  from  a 
sandy  marl  of  Jurassic  (Oxfordian)  age  in  the  Canton  of  Aargau 
(Switzerland),  which  includes  many  genera  now  known  to  us 
only  from  deep  water.  It  is  altogether  one  of  the  most  pro- 
nounced   and   characteristic    rhizopodal  faunas  recorded   in   the 


IN    THEIR    ROLE    AS    WORLD-BUILDERS.  7 

fossil  condition.  The  occurrence  of  this  rich  series  of  genera, 
some  of  which  appear  to  be  confined  to  this  formation  while 
others  are  hardly  known  except  in  the  recent  condition,  suggests 
that  the  arenaceous  foraminifera  have,  with  few  exceptions,  always 
been  confined  to  the  deep  sea,  and  that  their  scanty  geological 
history  may  be  due  to  that  fact,  and  to  the  rarity  of  ancient  deep- 
sea  deposits. 

Passing  to  the  Cretaceous  period,  we  find  the  Neocomian  and 
Aptian  strata  comparatively  devoid  of  recognisable  foraminiferal 
remains.  But  it  is  almost  certain  that  Foraminifera  of  the 
smaller  types  existed  in  enormous  numbers  in  the  seas  of  these 
periods,  leaving  their  evidence  behind  them  in  the  shape  of  the 
glauconitic  casts  and  grains  which  bulk  so  largely  in  the  Green- 
sands. 

The  Gault  of  England  and  the  Continent  contains  a  rich  and 
varied  foraminiferal  fauna  running  into  several  hundred  species. 
But  although  the  Rhizopoda  must  have  swarmed  in  the  Gault 
seas,  they  do  not  constitute  any  large  percentage  of  the  total 
mass  of  the  formation,  and  are  often  confined  to  limited  zones. 

The  same  remark  may  be  applied  to  the  numerous  beds  of 
•chalk  ranging  from  the  Chalk  Marl  to  the  Upper  Chalk.  It  is 
one  of  those  popular  beliefs  which  die  so  hard  that  chalk  is  made 
up  entirely  of  the  shells  of  the  Foraminifera,  and  the  textbooks 
and  microscopical  works  abound  with  statements  to  that  effect. 
Some  of  the  methods  suggested  to  students  for  the  obtaining  of 
specimens  can  only  have  originated  in  the  fertile  brains  of  the 
authors.  The  beginner  is  instructed  to  obtain  a  lump  of  chalk 
and  scrub  it  to  fragments  with  a  toothbrush  under  water ;  or  to 
place  some  lumps  in  a  bag  and  smash  them  up  with  a  hammer, 
subsequently  kneading  the  mass  under  a  tap  until  the  water  runs 
away  clear.  It  is  needless  to  say  that  such  methods  can  never 
produce  anything  but  debris  and  disappointment.  These  methods, 
together  with  directions  for  the  adequate  preparation  of  chalk 
material  for  examination,  have  been  fully  discussed  by  Heron- 
Allen  in  his  "  Prolegomena  "  (23). 

There  are  very  few  zones  in  the  Chalk  which  do  not  contain 
Foraminifera,  but  their  number  is  as  a  rule  small  compared  with 
the  whole  bulk  of  amorphous  matter.  But  it  is  probable  that 
in  the  Chalk  sea  the  Foraminifera  really  abounded,  and 
that  the  amorphous  carbonate  of  lime  is  derived  largely  from 


8        E.    HERON-ALLEN   AND   A.    EARLAND    ON    THE    FORAMINIFERA 

their  comminuted  and  dissolved  remains  subsequently  reprecipi- 
tated. 

Certain  zones  of  the  Chalk,  notably  the  zones  of  Holaster  planus 
and  Micrdster,  yield  Foraruinifera  in  larger  numbers,  but  even 
here  a  section  of  the  rock  will  show  their  limited  distribution^ 
The  bulk  of  the  organic  remains  will  be  found  to  consist  of  small 
spherical  bodies  which  when  cut  in  section  show  as  rings  (PI.  2r 
fig.  1).  These,  the  so-called  "  Spheres  "  of  the  chalk,  are  perhaps- 
the  origin  of  the  belief  that  chalk  is  built  up  of  the  shells  of 
Foraminifera.  But  whatever  the  "  Spheres "  may  be,  we  are 
convinced  that  they  are  not  Foraminifera.  Their  nature  is  still 
in  doubt,  although  they  have  been  relegated  in  turn  to  the 
Foraminifera,  the  Radiolaria  and  the  Diatomaceae.  Mr.  W.. 
Hill,  F.G.S.,  of  Hitchin,  whose  knowledge  of  the  microscopic 
structure  of  chalk  is  unrivalled,  and  who  has  devoted  many  years- 
to  the  study  of  these  "  Spheres,"  has  published  a  scheme  for  the 
division  of  the  Chalk  into  zones,  based  on  their  occurrence  and 
numbers  (32),  but  he  is  still  unable  to  explain  their  origin  and 
nature.  We  suggest  that  they  may  be  the  chitinous  tests 
Of  flagellate  infusoria  such  as  are  found  in  great  numbers  in  the 
sea  to-day,  of  practically  identical  size  and  shape. 

The  Chalk  of  Maestricht  is  rich  in  Foraminifera,  and  may 
be  regarded  as  the  starting-point  of  the  rich  Foraminiferal 
fauna  of  the  Tertiary  period,  as  it  contains  many  large  generar 
OrbiioliUs,  Operculina,  Orbitoides,  etc.>  which  reached  a  maxi- 
mum of  development  and  distribution  in  Eocene  and  Miocene 
times. 

Passing  into  Tertiary  times  we  reach  the  Golden  Age  of  the 
Foraminifera;  the  age  in  which  they  were  to  reach  their 
maximum  development  both  as  regards  size  and  abundance,  and 
to  leave  their  remains  in  great  beds  extending  across  whole 
continents,  and  often  of  an  enormous  thickness. 

These  Tertiary  Foraminifera  are  very  sparingly  represented 
in  Great  Britain.  The  London  clay,  although  it  contains  a  rich 
rhizopodal  fauna  in  a  limited  zone,  is  on  the  whole  absolutely 
barren,  and  the  Thanet  Sands  and  Woolwich  and  Beading  beds 
have  yielded  few  records. 

In  the  Bracklesham  beds  of  Hampshire,  however,  we  find  a 
zone  almost  entirely  composed  of  two  or  three  species  of  Nummu- 
lites.     At  Selsey  Bill  the  foreshore  at  low  tide,  on  the  east  shore, 


IN   THEIR    ROLE    AS    WORLD-BUILDERS.  0 

is  for  a  large  area  covered  with  an  exposure  of  this  zone  (the- 
41  Park "  beds),  and  one  cannot  walk  without  crushing  vast 
agglomerated  masses  of  Nummulites  laevigatas,  extending  for 
miles  and  occupying  broad  areas  between  tide-marks. 

Off  the  extremity  of  Selsey  Bill  lies  the  extensive  reef  known 
as  "The  Mixon."  It  is  exposed  at  low  tide,  and  is  then  found 
to  be  a  limestone  principally  composed  of  one  species  of  fora- 
minifer,  Alveolina  Boscii  Def ranee.  Other  species  (notably  a  large 
alveoliniform  Jliliolina,  Nummulites,  and  a  large  Polymorphina) 
are  to  be  found  in  the  rock,  but  this  is  dominant  (PL  2,  fig.  2). 
Alveolina  Boscii,  which  has  built  up  enormous  areas  of  limestone 
extending  across  Southern  Europe  to  the  Himalayas,  is  still  in 
existence  to-day,  and  is  now  forming  similar  deposits  off  many- 
tropical  shores.  The  Selsey  specimens — the  only  ones  to  be  found 
in  Great  Britain — are  indistinguishable  from  those  to  be  dredged 
in  shallow  water  to-day,  off  the  Great  Barrier  Reef  of  Queensland 
and  in  many  other  places  (24). 

At  Stubbington  and  its  neighbourhood,  in  Hampshire,  smaller 
types  of  Nummulites,  viz.  Nummulites  elegans  and  JV.  variolariar 
are  to  be  found  in  similar  abundance. 

Turning  to  the  Continent,  we  find  these  Nummulitic  and 
Alveoline  limestones  developed  to  an  incredible  extent.  With 
interruptions  here  and  there,  they  spread  in  a  broad  band  across- 
Europe,  Asia  and  Northern  Africa  to  the  Himalayas,  attaining 
in  many  places  a  thickness  of  several  thousand  feet  (PI.  2,  fig.  3). 
The  species  vary  with  the  zone  and  locality,  but,  as  a  rule,  the- 
whole  rock  is  built  up  of  their  more  or  less  perfect  remains,  and 
undeft  the  microscope  the  very  debris  in  the  interstices  of  perfect 
specimens  is  found  to  consist  of  their  comminuted  remains- 
(Pl.  2,  fig.  4  and  PI.  3,  fig.  1). 

Among  the  more  familiar  instances  of  Nummulitic  limestone- 
may  be  mentioned  the  Pyramids  of  Egypt,  which  are  built  of 
limestone  quarried  in  the  neighbouring  Mokattam  Hills,  largely 
composed  of  a  single  species  of  Nummulite — N.  Gizehensis  (Ehren- 
berg).  We  illustrate  in  Plate  3,  fig.  1  a  section  through  a  micro- 
spheric  specimen  of  this  Nummulite,  one  of  a  series  collected  for  us 
by  Mrs.  A.  M.  King,  F.R.M.S.  The  peculiarity  of  these  remains 
struck  the  geographer  Strabo,  who  accounts  for  their  presence  in 
the  limestone  by  asserting  that  they  were  the  petrified  remains 
of    lentils    from    the    rations    of    the    ancients    who    built    the 


10     E.    HERON-ALLEN   AND   A.    EARLAND    ON   THE    FORAMINIFERA 

Pyramids.*  They  are  to  this  day  known  locally  as  "  Pharaoh's 
beans."  t 

Philip  de  la  Harpe  begins  his  Monograph  on  the  genus  (27) 
with  the  words,  "  Egypt  is  the  classic  land  of  the  Nummulites," 
and  Dr.  Carpenter  in  his  Introduction  (28)  passes  in  review  the 
legends  which  have  attached  themselves  to  this  organism,  from 
Herodotus  (?),  Pliny  (?)  and  Strabo  to  the  learned  Clusius,  who 
refers  to  "  the  popular  belief  of  the  Transylvanians  that  they 
were  pieces  of  money  turned  into  stone  by  King  Ladislaus,  in 
order  to  prevent  his  soldiers  from  stopping  to  collect  them  just 
when  they  were  putting  the  Tartars  to  flight ! "  J 

Tt  may  be  remarked  that  Prof.  Haug  has  suggested  (31) 
abolishing  the  Lyellian  nomenclature  of  geological  periods  for  all 
epochs  later  than  the  Cretaceous,  and  the  redistribution  of  the 
strata  into  Nummulitic,  Neogene,  and  Quaternary.  He  suggests 
that  the  Nummulitic,  whose  classification  is  founded  solely  upon 
this  foraminifer  alone,  shall  be  divided  into  the  Eo-Nummulitic, 
which  will  comprise  the  Montian,  the  Thanetian,  and  the  Lon- 
■donian  (names  which  speak  for  themselves),  the  Meso-Nummu- 
litic,  which  will  comprise  the  Lutetian  and  Ludian,  and  the 
Neo-Nummulitic,  which  includes  all  strata  from  the  Lower 
Oligocene  up  to  the  dawn  of  the  Glacial  Period — which  com- 
mences his  Quaternary. 

As  a  rule  these  two  dominant  types,  Alveolina  and  Nummulites, 

*  Strabo,  Geographica,  lib.  xvii.  cap.  i.  §34:  cpaal  d'airoXidudrji'a.i  \el\pava 
tt?s  rdv  epya^ofxtvocv  rpocprjs.  ovk  direoiKe.  See  the  note  on  this  passage  in 
Canon  Rawlinson's  translation  (1860). 

f  In  spite  of  the  fact  that  Herodotus  (who  has  been  credited  with 
Strabo's  observation  on  the  Nummulites)  expressly  states  (Euterpe,  IT.  §  37) 
that  the  Egyptians  never  grew  or  ate  beans  in  any  form. 

X  Clusius  (i.e.  Charles  de  l'Ecluse,  1526-1609),  in  Caroli  Clusii  et  aliorum 
vpistolae,  Paris  (Epistola  xxxvii.),  thus  records  the  matter :  "  Intellexi  item 
genus  quoddam  lapillorum  planorum  et  quasi  circino  in  orbem  ductorum 
inveniri  in  montibus  qui  Pannoniam  a  Daciasive  Transilvania  disterminant, 
quorum  alii  auri,  alii  argenti  colorem  referunt  et  characteribus  insigniti 
videntur  sed  incognitis.  Ferunt  Ladislaum  regem  quum  Tartaros  praeda  et 
spoliis  onustos  persequeretur  atque  metueret,  ne  militum  suorum  avaritia 
■et  ignavia,  qui  thesauris  per  viam  stratis  ab  hostibus  inhaerebant,  victoria 
illi  e  manibus  eriperetur,  a  Deo  petiisse  ut  nummi  illi  et  pecunia  ab  hosti- 
bus in  via  relicta  in  lapides  mutarentur,  quo  militem  sic  delusum  alacriorem 
haberet  in  persequendo  hoste."  A  passage  contemporary  with,  if  it  should 
not  precede,  Mr.  C.  D.  Sherborn's  earliest  reference  to  Conrad  Gesner 
(1566). 


IN    THEIR    ROLE    AS    WORLD-BUILDERS.  11 

do  not  exist  together,  but  the  transition  from  one  dominant  to 
the  other  is  often  quite  sharp.  We  show  a  section  from  Sherani, 
on  the  N.W.  frontier  of  India,  illustrating  the  junction  of  the 
two  beds.  Within  a  thickness  of  two  inches  the  rock  turns  from 
a  Nummulitic  to  an  Alveoline  limestone  (PI.  3,  fig.  2).  What 
possible  explanation  can  there  be  for  such  a  radical  and  cata- 
clysmic change,  necessitating  the  practical  extinction  of  one 
dominant,  and  the  sudden  rise  to  prominence  of  another,  widely 
■different,  type?  It  cannot  be  a  case  of  evolution,  as  the  two 
species  represent  entirely  different  types  of  structure. 

With  the  passing  of  the  Eocene  period  the  Foraminifera  lose 
their  all-important  position  as  rock-builders.  Through  Oligocene 
and  Miocene  times  they  continued  to  flourish,  and  to  form 
•deposits  largely  or  entirely  built  up  of  their  remains.  The  genus 
-Nummulites  dies  out,  dies  so  completely  that  at  the  present  day 
it  is  represented  by  only  a  single  small  species  of  rare  occurrence 
in  tropical  seas.  Alveolina  persists,  but  no  longer  as  a  dominant. 
Orbitoides,  a  highly  specialised  type  which  had  made  its  first 
■appearance  in  the  Chalk  of  Maestricht,  attains  sudden  abundance 
and  forms  great  beds  of  Orbitoidal  limestone  in  all  the  Con- 
tinents, only  to  die  out  absolutely  in  the  Miocene  (PI.  3,  fig.  3). 
But  the  Miocene  and  later  Tertiary  deposits,  though  often 
presenting  an  abundant  and  extremely  varied  foraminiferal 
fauna,  no  longer  owe  their  existence  to  the  occurrence  of  one  or 
iew  species  in  enormous  numbers,  except  in  those  comparatively 
few  deep-sea  deposits  which  have  been  raised  to  the  surface 
in  the  West  Indies,  New  Guinea  and  the  Pacific,  and  which 
are  similar  in  structure  and  often  in  species  to  the  deposits 
which  are  being  found  in  the  deep  sea  to-day  (25)  (26)  (PI.  3, 

&s-i]-  .         .... 

Perhaps  the  conditions  under  which  foraminiferal  life  exists 
to-day  may  help  to  explain  the  change.  We  have  now  no  seas 
-swarming  with  Nummulites  and  Alveolina,  to  the  practical 
■exclusion  of  other  species  Here  and  there  about  the  world  the 
shallow-water  Foraminifera  are  to  be  found  in  such  .profusion 
that,  given  favourable  means  of  preservation,  we  should  have  in 
time  a  true  foraminiferal  limestone.  From  the  shallow  waters  of 
the  West  Indian  seas  we  have  received  dredgings  almost  entirely 
composed  of  the  genera  Orbiculina  and  Miliolina.  In  the  shallow 
lagoons  of  the  Pacific  Tinoporus  baculatus,  Alveolina  Boscii  and 


12      E.    HERON-ALLEN    AND    A.    EARLAND    ON    THE    FORAMINIFERA 

Orbitolites  complanata  still  form  banks  which  impede  navigation. 
But  speaking  generally,  the  activity  of  the  Foraminifera  to-day 
is  displayed  in  another  sphere.  In  the  surface  waters  of  the 
great  oceans  the  few  genera  which  are  found  in  the  pelagic- 
condition  swarm  in  countless  numbers,  and  their  dead  shells 
falling  constantly  to  the  sea  floor,  are  there  building  up  layers  of 
Globigerina  ooze  which,  if  solidified  and  raised  to  the  surface,, 
would  be  visible  as  areas  of  foraminiferal  limestone  exceeding 
even  the  Nummulitic  limestones  in  extent. 

Murray  and  Renard  estimate  the  area  of  sea  bottom  over 
which  Globigerina  ooze  is  at  present  in  process  of  formation  at 
over  49 1  million  square  miles.  Of  its  depth  we  can,  of  course,, 
form  no  idea,  but  as  the  great  oceans  are  practically  permanent,, 
it  must  be  very  great,  because  we  know  from  deep-sea  deposits 
which  have  been  elevated  into  land  surfaces  in  Malta,  Barbados,. 
Trinidad  and  Australasia,  that  similar  deposits  have  been  forming 
in  the  deep  sea  ever  since  at  least  Miocene  times.   ■ 

Prof.  Agassiz  has  observed  (29)  :  "No  lithological  distinction 
of  any  value  has  been  established  between  the  chalk  proper  and 
the  calcareous  mud  of  the  Atlantic,"  and  it  has  been  reasonably 
postulated  by  Prof.  Jukes-Brown  (30),  after  a  careful  analysis 
of  calcareous  oozes,  that  the  chalk  was  deposited  in  a  sea  of  less 
than  500  fathoms,  though  doubtless  at  a  considerable  distance 
from  land.  The  time  occupied  in  the  deposit  of  the  English 
chalk,  arguing  by  the  rate  at  which  the  Atlantic  ooze  is 
formed,  which  is  one  foot  in  a  century,  must  have  been 
150,000  years. 

We  cannot  but  feel  that  this  paper  has  already  overpassed  the 
reasonable  limits  of  such  a  communication,  but  our  difficulty  has 
been  mainly  one  of  selection.  The  matter  is  one  whose  ramifi- 
cations are  almost  infinite.  A  systematic  study  of  the  dynamics 
of  the  subject  remains  yet  to  be  completed,  though  significant 
beginnings  have  been  made  by  Prof.  Hull  and  by  Prof.  Jukes- 
Brown.  A  careful  consideration  of  the  factors  which  have  led 
to  the  deposition  of  certain  forms  of  Foraminifera  and  other 
microzoa  in  an  orderly  sequence,  dependent  for  the  most  part 
upon  current  action  and  specific  gravity,  must  lead  us  to  an 
understanding  of  the  forces  which  have  accounted  for  the 
Building  of  the  World  in  the  form  in  which  we  know  it.  And 
it  is  by  the  study*  of  such  factors,  as  revealed  by  their  results, 


IN   THEIR    RuLE    AS    WORLD-BUILDERS.  13 

that  geologists  have  been  able  to  reconstruct    the  geographical 
features  of  ages  inconceivably  remote. 

Bibliography. 

1.  Dawson,    J.    W.      On  the    Structure    of    Certain    Organic 

Remains  in  the  Laurentian  Limestones  of  Canada.      Quart. 
Journ.  Geol.  Soc,  1865,  p.  51,  pi.  vi.,  vii. 

2.  Carpenter,   W.    B.     Additional  Note  on  the  Structure  and 

Affinities  of  Eozoon  Canadense.  Quart.  Journ.  Geol.  Soc, 
1865,  p.  59,  pi.  viii.,  ix. 

3.  Ibid.     On  the  Structure,  Affinities  and  Geological  Position  of 

Eozoon  Canadense.  Intellectual  Observer,  No.  XI.,  p.  278. 
2  plates. 

4.  Cayeux,  L.     Sur  la  Presence  de  Restes  de  Foraminiferes  dans 

les  Terrains  precambriens  de  Bretagne.  Ann.  Soc.  Geol. 
Xord.,  1894,  vol.  xxii.,  pp.  116-19. 

5.  Ehrexberg,  C.  G.     Ueber  andere  massenhafte  mikroskopische 

Lebensformen  der  altesten  silurischen  Grauwacken-Thone 
bei  Petersburg.  Sitzungs.  phys.-math.  Kl.  Monatsb.  Ak. 
Wiss.,  Berlin,  1858,  p.  324,  pi.  i. 

6.  Matthew,  W.  D.     On  Phosphate  Nodules  from  the  Cambrian 

of  Southern  New  Brunswick.  Trans.  New  York  Acad. 
Science,  1893,  vol.  xii.,  pp.  108-20  and  pi.  i.-iv. 

7.  Matthew,  G.  F.     The  Protolenus  Fauna.     Trans.  New  York 

Acad.  Science,  1895,  vol.  xiv.,  pp.  109-11,  pi.  i. 
S.  De  Lapparent,  A.     Traite  de  Geologie,  4th  ed.,  1900,  Paris, 
p.  790. 

9.  Chapman,     F.       Foraminifera    from    an    Upper    Cambrian 

Horizon  in  the  Malverns.  Quart.  Journ.  Geol.  Soc,  1900, 
pp.  257-63,  pi.  xv. 

10.  Keeping,  W.     On  some  remains  of  Plants,  Foraminifera  and 

Annelida  in  the  Silurian  Rocks  of  Central  Wales.  Geo- 
logical Magazine,  1882  ;  Dec.  II.,  vol  ix.,  p.  490. 

11.  Blake,  J.  F.      Lower   Silurian    Foraminifera.       Geological 

Magazine,  1876,  N.S.  (Dec.  II.),  vol.  iii.,  p.  134. 

12.  Brady,  H.  B.     Note  on  some  Silurian  Lagenae.     Geological 

Magazine,  1888,  pp.  481-84. 

13.  Terquem,     O.       Observations      sur    quelques    fossiles    des 

Epoques  Primaires.  Bull.  Soc.  Geol.  France,  Ser.  3  (1880), 
vol.  viii.,  pp.  414-18,  and  pi.  xi. 


14     E.    HERON-ALLEN    AND   A.    EARLAND   ON    THE    FORAMINIFERA 

14.  Chapman,  F.     On  some  Fossils  of  Wenlock  Age  from  Mulder 

near  Klinteberg,  Gotland.  Ann.  Mag.  Nat.  Hist.,  1901r 
pp.  141-60,  pi.  iii. 

15.  Vine,  G.  R.     Notes  on  the  Annelida  tubicola  of  the  Wenlock 

Shales  from  the  washings  of  Mr.  G.  Maw,  F.G.S.  Quart, 
Journ.  Geol.  Soc,  vol.  32  (1882),  p.  390.  See  also 
F.  Chapman,  Ann.  Mag.  Nat.  Hist.,  1895,  Ser.  VI.,. 
vol.  xvi.,  p.  311. 

16.  Chapman,  F.     The  Foraminifera.     London,  1902,  p.  255. 

17.  Ibid.     Note  on  the  specific  name  of  the  Saccammina  of  the 

Carboniferous  Limestone.  Ann.  Mag.  Nat.  Hist.,  1898, 
Ser.  7,  vol  i.,  pp.  216-18. 

18.  Chapman,    F.,    and   Howchin,   W.     A    monograph    of   the 

Foraminifera  of  the  Permo-Carboniferous  Limestones  of 
New  South  Wales.  Mem.  Geol.  Survey,  New  South  Wales, 
1905.     Palaeontology,  No.  14,  p.  5. 

19.  Chapman,  F.     On  some  Foraminifera  of  Rhaetic  Age  from 

Wedmore,  in  Somerset.  Ann.  Mag.  Nat.  Hist.,  1895r 
Ser.  6,  vol.  xvi.,  pp.  305-29,  2  plates. 

20.  Haeusler,    P.       Die    Astrorhiziden    und    Lituoliden    der 

Bimammatus-zone.  Neues  Jahrb.  filr  Min.,  1883,  vol.  i.r 
pp.  55-61,  pi.  iii.,  iv. 

21.  Ibid.     Monographie  der  Foraminiferen  der  Transversarius- 

Zone.  Abhandl.  Schiveiz.  Paldont.  Gesellsch.,  1891,, 
vol.  xvii.,  pp.  1-135,  15  plates. 

22.  Mobius,  K.     Der  Bau  der  Eozoon  Canadense  nach  einigen 

Untersuchungen  vergleichen  mit  dem  Bau  der  Foramini- 
feren.    Cassel,  1878. 

23.  Heron-Allen,  E.     Prolegomena  towards  the  study  of  the 

Chalk  Foraminifera.     London,  1894,  pp.  10-14. 

24.  Heron-Allen,  E.,  and  Earland,  A.    The  Recent  and  Fossil 

Foraminifera  of  the  Shore-sands  at  Selsey  Bill,  Sussex. 
Journ.  R.  Micr.  Soc,  1908,  p.  529;  1909,  pp.  306,  422r 
677  ;  1910,  pp.  401,  693  ;  1911,  pp.  298,  436. 

25.  Schubert,  P.      Die  fossilen  Foraminiferen  der  Bismarck- 

archipels  und  einiger  angrenzender  Inseln.  K.  K.  Geo- 
logischen  lieichsanstalt,  vol.  xx.     Part  4.  Vienna,  1911. 

26.  Jukes-Brown,  A.  J.,  and  Harrison,  J.  B.     The  Geology  of 

Barbados.  Part  II.  The  Oceanic  Deposits.  Quart. 
Joarn.  Geol.  Soc,  1892,  vol  48,  p.  170. 


IN    THEIR    ROLE    AS    WORLD-BUILDERS.  15 

27.  La  Harpe,  P.  de.     Monographie  der  in  Aegypten  und  der 

libyschen  Wiiste  vorkommenden  Nummuliten.     Palaeonto- 
graphica,  vol.  xxx.  1883  (3  Folge,  Bd.  36),  p.  155. 

28.  Carpenter,  W.  B.,  Parker,  W.  K.,  Jones,  T.  B.     Intro- 

duction to  the  study  of  the  Foraminifera.      London  (Ray 
Soc),  1852,  p.  262. 

29.  Agassiz,   A.     Three  Cruises  of  the  Blake.     London,  1888,. 

vol.  i.,  p.  150. 

30.  Jukes-Brown,    A.    J.      Handbook    of    Physical    Geology. 

London,  1884,  p.  130. 

31.  Haug,  E.    Traitede  Geologic    II.  Les  Periodes  Geologiques. 

Fascicule  3.     Paris,  1911. 

32.  Jukes-Brown,  A.  J.     The  Cretaceous  Bocks  of  Britain,  with 

contributions  by  W.    Hill.     London,  Geological    Survey, 
volii.,  1903,  vol.  iii.,  1904. 


Description  of  Plates  1 — 3. 

With  the  exception  of  PI.  1,  fig.  1,  PI.  3,  fig.  4,  the  figures  are 
from  original  sources. 

Plate  1. 

Fig.  1.  Spirillina  Limestone.  Upper  Cambrian,  Malvern  (after 
Chapman,  Q.J.G.S.,  vol.  lvi.,  1900,  Plate  15). 

,,  2.  Saccammina  Limestone.  Carboniferous.  Pathhead,  Had- 
dington, N.B. 

,,    3.    Endothyra  Limestone.     Carboniferous.     Indiana. 

„  4.  Nubecularia  Limestone.  Permo- carboniferous.  Polkolbin, 
Maitland,  N.  S.  Wales. 


Plate    2. 

Fig.  1.    Middle  Chalk.     Zone  of  Rhynchonella  Cuvieri.     Hitchin. 
,,    2.    Alveolina  Limestone.    Eocene.     Mixon  Bock,  Selsey. 
,,    3.    Alveolina  Limestone.    Eocene.     Bunnu,  N.  W.  Frontier 

India. 
,    4.    Kummulitic  Limestone.     Eocene.     Gizehj  Egypt. 


16      E.    HERON-ALLEN    AND    A.    EARLAND    ON    THE    FORAMINIFERA. 

Plate    3. 

Fig.  1.    Nummulites  Gizehensis  (Ehrenberg),  microspheric  speci- 
men.    Horizontal  section,  through  primordial  chamber. 
„     2.    Alveolina  and  Nummulitic  Limestone.    Eocene.    Shiranni, 
N.  W.    Frontier,    India,  showing   the  junction  of   the 
two  beds. 

3.  Orbitoidal  Limestone.     Miocene.     Japan. 

4.  Globigerina  Limestone.    Miocene.    Bismarck  Archipelago, 
Pacific  (after  Schubert,  loc.  cit.,  Plate  5,  fig.  4). 


Jourii.  Quekett  MicroscopicabClub,  Ser.  2,  Vol.  XIL,  No.  72,  April  1913. 


Journ.  Q.M.C. 


Ser.  2,  Vol.  XII.,  PI.  1 


3  4 

Fo  RAM  IN  I  FERAL    LIMESTONES. 


Journ.   Q.M.C. 


Ser.  2,  Vol.  XII.,  PI.  2. 


FoRAMINIFERAL    LIMESTONES. 


Journ.  Q.M.C. 


Ser.  2,  Vol.  XIL,  PL  3. 


3  4 

FORAMINIFERAL    LIMESTONES. 


17 


NOTES    ON    SOME    OF    THE    DISCOID    DIATOMS. 

By  W.  M.  Bale,  F.R.M.S. 


(Contributed  by  Prof.  A.  Bendy,  January  2Sth,  1913.) 

In  the  following  notes,  written  for  the  most  part  several  years 
since,  I  have  attempted,  in  somewhat  desultory  fashion,  a  survey 
of  some  of  the  principal  characters  which  have  been  utilised  in 
the  discrimination  of  species  in  three  or  four  of  the  best-known 
genera  of  discoid  diatoms.  Some  of  the  conclusions  at  which  I 
have  arrived  as  to  the  inadequacy  of  many  of  these  distinctions 
have,  I  am  aware,  been  reached  by  previous  observers,  more 
especially  in  the  genus  Coscinodiscus ;  but  in  such  cases  the 
special  instances  now  brought  forward  may  perhaps  be  service- 
able in  reinforcing  those  conclusions.  In  other  cases,  particularly 
in  the  genus  Actinoptychus,  my  observations  tend  to  prove  that 
characters  accepted  as  specific  even  by  recent  authors  are  de- 
monstrably unreliable.  I  have  not  pursued  my  investigations 
more  fully,  as  I  have  found  the  subject  too  difficult,  owing  to  the 
impossibility  of  procuring  much  of  the  literature,  and  to  my  total 
isolation  from  other  observers.  I  trust,  however,  that  these  notes 
may  not  be  without  interest  for  students  of  the  Diatomaceae, 
and  that  the  suggestions  therein  may  be  of  some  value  to  those 
who  occupy  themselves  with  their  classification. 

Coscinodiscus. — Notwithstanding  all  that  has  been  done  to- 
wards the  elucidation  of  this  unwieldy  genus,  it  still  remains  the 
most  difficult — as  it  is  the  most  extensive — of  the  whole  order. 
This  follows  naturally  from  the  general  similarity  of  form,  and 
the  absence  in  most  cases  of  any  specialised  areas  or  conspicuous 
appendages  such  as  serve  to  distinguish  the  species  in  Actin- 
cptychus,  A  uliscus,  etc.     Many  forms  which  have  been  described  as 

Journ.  Q.  M.  C,  Series  II. — No.  72.  2 


18  W.    M.    BALE    ON    SOME    OF   THE   DISCOID    DIATOMS. 

distinct  differ  only  in  having  the  markings  a  little  smaller  or 
larger,  while  others  are  characterised  by  trifling  distinctions  of 
detail  which,  on  examination  of  an  extended  series  of  specimens, 
are  found  to  break  down  utterly.  On  the  other  hand  it  will  be 
seen  that,  in  many  instances,  details  which  might  be  helpful  in 
the  discrimination  of  species  have  been  generally  overlooked. 

The   first   serious    attempt    to    grapple    with    the   difficulties 
involved  in  the  classification  of  the  genus  was  that  of  Grunow,. 
in  his  work  on  the  Diatoms  of  Franz-Josef  Land,  a  perusal  of 
which  leads  one  to  regret  that  this  acute  observer  did  not  carry 
out  a  more  comprehensive  survey  of  the  whole  genus.     Rattray's 
Revision,  though  giving  evidence  of  a  vast  amount  of  painstaking 
research,  is  far  from   final  in  regard   to    the  species  admitted, 
many  of  which  are  characterised  by  features  obviously  not  of 
specific — sometimes  not  even  of  varietal — value.     Moreover,  in 
working  over  slides  from  well-known   deposits,  one  finds  many 
forms  which  it  is  impossible  to  place  under  any  of  the  species 
described,  though  it  is  most  unlikely  that   Rattray  could  have 
failed  to  observe  them.     The  impression  is  produced  that  many 
of  the  descriptions  have  been   framed   on  particular  specimens,, 
without  any  allowance  for  the  range  of  variation  usually  present. 
The  "key"  is  minimised  in  value  owing  to  the  use  in  many  of 
the  sections  of  characters  which  are  quite  inconstant,  or  which 
may  characterise  the  type  but  not  the  varieties,  while  the  attempt 
to  include  all  the  sections  in  one  key  has  added  much   to  the 
difficulty  of  the  undertaking,  and  has  involved  mistakes  which 
render  it  in  some  cases  quite  unreliable.     (As  an  example,  let 
the  observer  take  a  typical  valve  of  C.  asteromphalus  and  attempt- 
to  trace  it  through  the  key,  and  he  will  fail  to  find  it.     But  it 
appears  under  Section  116,  and,  if  followed  backwards,  it  will 
be  referred  to  Section  111,  where  the  description  is,  "Markings 
rounded,  granular ;  interspaces  hyaline,   unequal,  rows  radial," 
which  obviously  cannot  apply  to  the  species  at  all.) 

Nevertheless  Rattray's  work  undoubtedly  represents  a  great 
advance  in  its  suppression  of  a  large  number  of  pseudo-species, 
though  one  cannot  but  regret  that  the  process  has  not  been 
carried  further. 

Mr.  Cox,  going  to  the  opposite  extreme,  would  reduce  all  the 
multitudinous  forms  of  Coscinodiscus  to  seven  species,  Actinocyclus 
Ehrenbergii  being   included   as   one   of   them.     Some  diatomists 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  19 

have  expressed  approval  of  this  proposal,  but  none  have  adopted 
it,  nor  are  any  likely  to  do  so. 

In  surveying  the  various  characters  by  which  species  may  be 
defined,  the  outline  will  naturally  be  the  first  to  be  considered. 
This  in  the  Coscinodisci,  however,  is  of  little  assistance,  as,  except 
in  a  few  aberrant  species,  the  circular  form  prevails.  Passing  to 
the  surface  contour,  we  have  a  character  which  has  been  utilised 
by  Grunow,  Rattray,  and  others,  but  by  no  means  so  fully  as 
might  be.  Thus  neither  of  these  observers,  in  differentiating 
C.  asteromphalus  from  C.  centralis,  refers  to  the  fact  that  the 
former  has  usually  the  centre  depressed,  while  the  latter  is 
convex  throughout.  In  several  cases  the  absence  of  information 
on  this  point  in  Rattray's  descriptions  just  renders  the  diagnosis 
doubtful.  And  this  is  the  more  important  from  the  fact  that 
even  a  good  figure  does  not  always  bring  out  this  special  point. 
At  the  same  time  it  may  be  observed  that  it  is  not  rare  for 
individuals  of  a  given  species  to  depart  from  the  normal  character 
in  regard  to  surface  contour,  and  further,  that  in  particular 
localities  this  variation  may  prevail.  This  refers  especially  to  a 
tendency  for  the  surface  to  be  more  depressed  than  is  normally 
the  case,  and  does  not  apply  to  C oscinodiscus  only.  Thus  in  some 
of  the  Oamaru  deposits  we  find  that  Aulacodiscus  margaritaceus, 
A.  amoenus  and  the  large  forms  of  the  Triceratium  favus  group 
are  all  characterised  by  the  unusually  depressed  surface  of  the 
valves. 

It  may  be  noted,  further,  that  it  is  not  safe  to  describe  the 
surface  contour  of  a  species  without  examining  both  valves. 
Rattray  describes  C.  superbus  as  convex,  but  in  reality  one  valve 
is  convex,  while  the  other  has  the  centre  depressed.  Several 
species,  such  as  C.  tumidus,  have  the  surface  concentrically  undu- 
lated, while  in  a  series  of  forms,  described  by  Grunow  as  Pseudo- 
Stephanodiscus,  there  is  an  asymmetrical  inflation  of  the  surface. 
The  inflations  and  depressions  in  C.  excavatus  are  also  familiar 
examples  of  specialised  areas. 

Variations  of  the  radial  symmetry,  other  than  those  men- 
tioned, are  rare.  A  notable  instance  is  that  of  C.  cocconeiformis, 
which  has  the  markings  bilaterally  arranged. 

In  the  great  majority  of  cases  the  form,  size  and  arrangement 
of  the  cellules  or  puncta  which  cover  the  surface  are  the  prin- 
cipal or  sole  ground  relied  upon  for  specific  distinction,  many 


20  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

so-called  species  being  differentiated  solely  by  slight  variations  in 
the  size  of  the  areolation,  or  by  its  increasing  or  decreasing 
in  size  towards  the  margin.  All  such  species,  unless  other  and 
weightier  differences  can  be  found,  should  be  swept  aside  as 
spurious.  The  same  remark  applies  to  the  presence  or  absence 
of  a  central  area,  of  a  central  rosette  of  larger  areolae,  of 
bright  points  at  the  origin  of  the  shorter  radial  series,  of  parts 
of  the  surface  where  the  polygonal  areolation  is  replaced  by 
separate  circular  cellules,  and  of  fine  punctate  secondary  markings. 
Any  of  these  characters  may,  of  course,  be  constantly  associated 
with  a  particular  species;  but,  in  many  species  at  any  rate, 
examination  of  a  sufficient  series  readily  shows  that  they  may  be 
indifferently  present  or  not.  Indeed,  within  the  limits  of  the 
single  species  C.  asteromphalus  a  range  of  forms  may  be  found 
some  or  other  of  which  exhibit  every  one  of  the  characters  just 
mentioned,  while  others  show  none  of  them. 

In  some  respects  the  size  of  the  valve  (i.e.  with  reference  to 
the  average  of  the  species)  is  a  determining  factor  in  the 
arrangement  of  the  markings.  Thus  in  such  forms  of  C.  radiatus 
as  are  usually  considered  typical  there  are  commonly  three  or 
four  slightly  larger  cellules  in  the  centre,  and  the  rest  are  in 
distinctly  radial  series.  In  smaller  valves  the  central  cellules 
are  no  longer  than  the  rest,  and  in  the  smallest  forms  the  radial 
disposition  of  the  cellules  is  totally  lost.  A  still  more  striking 
instance  is  found  in  one  of  the  robust  forms  of  C.  asteromphalus, 
common  in  some  of  the  North  American  deposits.  The  largest 
valves  have  a  conspicuous  central  rosette  of  large  cellules,  and 
outside  these  the  areolae  are  much  smaller,  gradually  increasing 
in  size,  however,  to  the  mid-radius.  With  a  diminution  in  the 
size  of  the  valve  comes  a  modification  in  the  direction  of  levelling 
down  the  differences  in  size  of  the  areolation — the  rosette-cells 
become  smaller,  and  those  next  to  them  larger  in  proportion. 
One  stage  in  this  series  is  the  C.  biangulatus  of  Schmidt,  which 
is  only  a  normal  form  of  this  group,  and  by  no  means  of  specific 
or  even  varietal  value.  In  the  smallest  forms  of  the  series  all 
trace  of  the  rosette  is  wanting,  the  areolae  are  fairly  uniform  in 
size  throughout,  and  the  centre  of  the  valve  is  not  depressed  as 
in  larger  specimens,  but  convex  or  very  slightly  flattened,  while 
in  many  valves  the  cellules  are  separate  and  circular  on  part  of 
the  surface,  as  in  C.  perforatus  and  C.  apiculatus.     Similarly  the 


-I 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  21 

C.  crassus,  so  abundant  in  the  Sendai  deposit,  simply  consists  of 
the  smaller  valves  of  the  equally  abundant  G.  borealis,  to  which 
•    it   bears   the    same   relationship    that    C.    biangulatus    does    to 
C.   asteromphalus. 

In  C.  marginatus  the  small  valves,  with  uniform  and  non- 
radial  areolation,  are  considered  typical,  but,  as  in  the  above- 
mentioned  species,  we  find  that  valves  of  maximum  size  have  the 
areolation  distinctly  radial,  with  the  areolae  increasing  in  size 
from  the  central  rosette  towards  the  margin. 

In  other  species  similar  conditions  occur,  indicating  that  the 
reduction  of  the  differences  in  size  of  the  areolae  is  the  regular 
concomitant  of  the  reduction  in  size  of  the  valves,  and  showing 
how  little  such  variations  are  to  be  relied  on  as  specific 
distinctions. 

The  presence  of  a  central  area  may  be  of  specific  value  in 
some  instances,  but  in  many  species  it  is  quite  worthless  even  as 
a  varietal  character.  Sometimes  its  disappearance  is  due  to  the 
cellules  surrounding  it  becoming  enlarged  at  its  expense.  Thus 
in  C.  perforatus  and  C.  apiculatus  normal  valves  (if  indeed  wo 
are  right  in  considering  as  normal  those  valves  with  separate 
round  markings,  which  I  greatly  doubt)  have  a  blank  central 
space,  and  the  cellules  surrounding  it  are  in  no  way  different 
from  the  rest,  but  when,  by  the  enlarging  of  the  cellules- 
generally  at  the  expense  of  the  intervening  substance,  the 
structure  becomes  areolate,  the  most  central  cellules  often 
enlarge  inwards  till  they  obliterate  the  area,  and  thus  form  a 
rosette,  as  in  C.   Oculus  Iridis,  etc. 

Far  too  much  importance  has  been  attached  to  the  area  in 
Rattray's  monograph,  especially  in  the  key. 

The  central  rosette  is  one  of  the  most  variable  of  characters. 
In  some  cases,  as  already  mentioned,  it  is  conspicuous  in  the 
largest  valves,  dwindling  and  finally  vanishing  in  the  smaller 
ones  ;  in  others,  just  alluded  to,  it  results  from  the  obliteration, 
entire  or  partial,  of  the  central  area.  In  some  no  doubt  it 
may  be  regarded   as  a  fairly  constant  specific  character. 

The  tendency  in  some  species  for  the  polygonal  areolation  to 
be  replaced  on  a  portion  of  the  valve  by  isolated  circular  cellules 
may  be  briefly  referred  to.  C.  perforatus  and  C.  apiculatus  are 
familiar  cases  in  which  this  modification  occurs,  either  over  the 
whole  surface  of  the  valve,  or  on  more  or  less  of  one  side,  while 


22  W.    M.    BALE    ON  .SOME    OF    THE    DISCOID    DIATOMS. 

in  C.  gigas,  G.  diorama,  and  a  few  others,  it  is  the  central  part 
of  the  valve  which  is  so  modified.  Though  in  C.  apiculatus  and 
C.  perforat us  it  is  universally  recognised  that  this  peculiarity  is 
not  of  specific  importance,  the  loose  disposition  of  the  markings 
in  the  central  part  of  such  species  as  C.  diorama  has  been  made 
use  of  to  characterise  the  species,  but  in  some  cases  at  least 
unwarrantably.  In  a  species  found  in  Port  Phillip  the  larger 
valves  have  the  markings  as  in  G.  diorama,  while  the  smaller 
ones  are  areolate  throughout.  When  the  modification  in  question 
occurs  in  the  central  part  of  a  valve  it  is  usually  associated  with 
a  thinner  condition  of  the  silex,  but  this  does  not  appear  to  be 
the  case  in  such  species  as  G.  perforatus  and  G.  apiculatus. 

In  rare  cases  the  loosely  disposed  and  rounded  markings  occur 
on  an  annular  area,  concentric  with  the  margin,  and  an  interest- 
ing example  of  this  is  found  in  the  large,  robust  form  of  G.  Oculus 
Iridis  found  in  the  Mors  deposit.  It  is  a  variable  form  as  regards 
the  surface  contour,  but  commonly  in  large  valves  the  centre  and 
the  sub-marginal  zone  are  about  equally  elevated,  and  the  inter- 
vening broad  annular  area  is  slightly  depressed.  A  varietal 
form  differs  in  having  this  depression  much  deeper,  and,  on  the 
outer  side,  very  abrupt,  while  in  a  third  form  the  annular 
depression  is  very  deep  and  narrow,  and  on  the  bottom  of  the 
depression  the  cellules  are  rounded  and  separate  (a  condition  to 
which  there  is  sometimes  a  tendency  in  the  second  form).  This 
last  variety  was  described  by  Grunow  in  his  work  on  the  diatoms 
of  Franz-Josef  Land  as  a  new  species,  under  the  name  of 
G.  annidatus,  notwithstanding  which  it  was  figured  later  on 
PI.  184  of  Schmidt's  Atlas  under  the  name  of  Craspedodiscus 
Molleri. 

I  have  also  seen  a  form  of  G.  excavatus,  very  near  to  Grunow' s 
var.  semilunaris,  in  which  there  is  a  complete  annular  depression, 
with  round  markings,  not  far  from  the  centre. 

The  circular  areas  of  the  varieties  just  mentioned,  as  well  as 
the  inflations  of  ordinary  forms  of  G.  excavatus,  are  all  instances 
of  abrupt  bulging  in  (or  out)  of  the  substance  of  the  valve,  and 
in  all  of  them  the  portion  which  is  subject  to  this  bulging 
appears  thinner  than  the  rest  of  the  valve,  while  the  markings 
are  fainter,  as  well  as  being  rounded  and  loosely  disposed. 

The  occurrence  of  "  bright  points  "  at  the  origin  of  the  shorter 
radial  series  of  cellules  has  been  commonly  regarded  as  a  valid 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  23 

specific  character.  In  some  instances  these  "  bright  points  "  are 
merely  the  optical  expression  of  a  local  thickening  of  the  silex ; 
more  generally,  however,  they  are  true  cellules,  differing  from  the 
rest  in  their  minute  size.  They  are  conspicuous  in  C.  perforatus, 
and  they  form  the  principal  ground  of  distinction  between  that 
species  and  C.  apiculatus.  But  in  examining  a  large  series  of 
€.  perforatus  var.  ceilulosa  I  find  them  by  no  means  so  constant 
as  to  justify  the  importance  attached  to  them.  While  in  some 
valves  they  appear  at  the  origin  of  all,  or  nearly  all,  the  shorter 
rows  of  areolae,  in  others  they  are  much  sparser,  and  in  a  few 
cases  I  failed  to  detect  more  than  four  or  five  on  the  whole  valve. 
In  such  cases,  and  when,  as  often  happens,  the  central  area  is 
obsolete,  it  is  a  critical  matter  indeed  to  distinguish  the  valve 
from  C.  radiatus,  and  in  passing  I  may  note  that  the  "  C.  radiatus" 
of  my  Holler's  Typen-Platte  is  just  one  of  these  valves  of 
C.  perforatus  var.  ceilulosa,  with  all  its  bright  points  complete. 
C.  obscurus  may  be  mentioned  as  another  species  in  which  the 
bright  points,  usually  present,  may  be  either  totally  absent  or 
reduced  to  a  very  small  number.  On  the  other  hand  the  points 
often  occur  in  species  which  are  normally  without  them.  I  have 
met  with  instances  of  this  kind  in  C.  aster  omphalus,  on  a  narrow 
unilateral  area  where  the  cellules  are  separate  and  rounded.  In 
a  slide  from  Cambridge,  Barbados,  there  are  numerous  valves  of 
C.  excavatus,  most  of  which  display  these  minute  cellules,  and  in 
some  valves  not  only  at  the  origin  of  the  radial  series,  but 
profusely  interspersed  among  the  large  areolae  all  over  the 
surface,  even  in  places  other  than  the  angles  of  the  areolae.  And 
I  have  a  curious  valve  of  Endyctia  oceanica,  in  which  these 
minute  cellules  form  the  principal  part  of  the  areolation,  the 
ordinary  large  cells  only  existing  in  scattered  groups  of  four  or 
five,  surrounded  on  all  sides  by  the  network  of  small  ones. 

I  have  referred  already  to  the  small  importance  to  be  attached 
•to  mere  differences  in  the  size  of  the  areolation,  but  I  would 
further  remark  that  it  must  by  no  means  be  assumed  that  only 
small  differences  are  to  be  disregarded.  Valves  of  C.  concinnus 
may  have  only  four  cellules  in  0*01  mm.,  while  others  may  have 
as  many  as  twelve,  though  the  valve  may  be  much  larger.  And 
I  have  seen  a  frustule  of  C.  excentricus  in  which  one  valve  was 
twice  as  finely  marked  as  the  other.  Such  instances  show  forcibly 
the  futility  of  distinctions  founded  on  the  size  of  the  areolation. 


24  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 


\ 


The  structure  of  the  valve-border  is  a  feature  which  has  not 
always  received  sufficient  attention  from  observers,  who  have 
overlooked  peculiarities  which  might  be  of  service  in  classification. 
This  refers  to  the  general  character  of  the  border,  and  more 
particularly  to  the  minute  appendages  which  it  frequently  bears. 
The  apiculi  which  form  a  circlet  at  the  margin  of  many  species 
are  familiar  to  all  observers,  more  especially  those  which  in  some 
of  the  Fasciculati  and  Cestodiscoidales  attain  a  prominence  which 
could  not  fail  to  attract  attention.  But  those  which  are 
asymmetrical,  and  of  which  only  one  or  two  appear  on  each  valve, 
have  hitherto  singularly  escaped  notice,  except  in  a  very  few 
instances,  where  they  are  more  conspicuous  than  usual.  For 
example,  in  the  robust  form  of  C.  lineatus,  described  as  C.  leptopus, 
a  single  larger  apiculus,  farther  in  than  the  rest,  is  quoted  by 
Rattray  as  distinguishing  C.  leptopus  from  its  allies.  Y~et  in 
fact  it  is  not  peculiar  to  this  form,  a  similar  apiculus,  but  more 
delicate,  being  easily  discoverable  in  other  and  more  nearly 
typical  forms  of  C.  lineatus.  Further,  it  is  equally  a  feature  of 
C.  excentricus,  and  I  find  it  commonly  present,  though  apparently 
hitherto  unnoticed,  in  forms  of  that  species  from  such  different 
localities  as  Port  Phillip,  Cuxhaven,  Santa  Monica,  and  Peru  and 
Bolivia  guanos.  (There  is,  of  course,  no  justification  for  the  line 
of  demarcation  drawn  by  Battray  between  the  respective  groups 
of  the  Lineati  and  the  Excentrici.  The  two  type  species  are  con- 
nected by  intermediate  forms,  and  the  same  remark  applies  to 
C.  excentricus  and  C.  subtilis.) 

Among  the  Badiati  the  tendency  is  towards  the  production  of 
two  apiculi,  which  occupy  positions  about  one-third  or  one-fourth 
of  the  circumference  apart.  They  are  found  in  many  species,, 
though  strangely  enough  I  can  find  no  mention  of  them  by  any 
observer  except  in  the  cases  of  G.  concinnus  and  C.  centralis,  in 
both  of  which  forms  they  are  very  conspicuous.  Battray  says 
that  C.  centralis  is  distinguished  from  C.  asteromphalus  by  these 
apiculi,  and  cannot  be  united  with  it  in  the  same  species,  as  pro- 
posed by  Grunow.  An  unfortunate  dictum,  since  all,  or  nearly 
all,  of  the  numerous  varieties  of  C.  asteromphalus  agree  precisely 
with  C.  centralis  in  this  respect,  while  such  apiculi,  but  more 
rudimentary  and  indefinite,  are  found  in  a  wide  range  of  forms 
comprised  under  C.  marginatus,  C.  perforates,  C.  apiculatusr 
C.  borealis  and  others.     Their  minute  size  and  indefinite  form 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  25- 

cause  them  to  be  easily  overlooked  against  the  coarsely  marked 
background  of  the  valve-areolation,  but  in  C.  concinnus  and 
G.  centralis  they  are  more  conspicuous,  owing  largely  to  the  more 
delicate  and  transparent  condition  of  the  valve. 

The  key  to  the  position  of  these  apiculi  is,  however,  to  be  found 
in  certain  modifications  of  the  valve-border  which  occur  in  the 
vicinity,  and  which  indeed  are  often  obvious  when  it  is  difficult 
or  impossible  to  detect  the  apiculi  themselves.  These  modifications 
may  take  the  form  of  a  thinning  away  of  the  valve-surface  (C. 
marginatus),  or  an  apparent  notching  of  the  margin  (C.  borealis, 
C.  diorama,  etc.),  or  a  sinuation  of  the  inner  edge  of  the  thickened 
border  (G.  aster  omphalus) .  In  the  last  species  this  marginal 
structure  is  very  conspicuous,  at  least  in  the  robust  valves,  and  it 
is  shown  in  Schmidt's  figures  of  C.  biangulatus  and  one  or  two 
others. 

In  C.  perforatus  and  C.  apiculatus  (at  least  in  the  areolate 
forms)  two  minute  notches  in  the  extreme  margin  of  the  areo- 
lation  can  in  most  cases  be  seen,  and  by  careful  examination  the 
apiculi  may  generally  be  found  opposite  them,  but  they  appear 
no  more  than  a  slight  thickening  of  the  silex,  wThich  would 
certainly  never  be  noticed  except  for  the  marginal  clue.  In 
C.  marginatus  the  coarse  radial  structure  of  the  marginal  zone  is 
thinned  away  over  two  comparatively  large  areas,  sometimes  very 
noticeably,  but  the  apiculi  themselves  are  difficult  to  make  out. 

The  apiculi  are  most  fully  developed  in  C.  centralis  and  C. 
aster omiAalus.  They  are  best  seen  by  examining  the  inside  of 
a  large  valve  in  which  the  marginal  part  is  steeply  convex,  so 
that  the  apiculi,  which  project  into  the  valve  a  little  above  the 
rim,  can  be  observed  without  the  interference  of  an  immediate 
background.  The  apiculus  takes  the  form  of  a  minute  disc, 
attached  by  a  central  point,  and  bearing  a  sub-globular  or  irregular 
mass.  The  border  in  C.  asteromphalus  is  usually  widened  in- 
wardly so  as  to  form  an  annular  projection  into  the  cavity  of 
the  frustule.  The  extent  to  which  this  widening  takes  place 
varies  greatly,  even  in  the  same  variety ;  but  whatever  its  width, 
so  long  as  it  projects  inwards  at  all,  it  is  sinuated  under  the 
apiculi,  which  are  always  uncovered,  so  that  the  sinuations  are 
deeper  as  the  valve-border  is  wider.  The  structure  would  seem 
to  imply  the  presence  in  the  living  organism  of  some  direct 
communicating  filaments  between  the  apiculi  of  the  two  valves, 


)  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

on  which  the  inward  extension  of  the  border  must  never  encroach. 
I  have  had  no  opportunity  of  proving  whether  this  is  so,  or  even 
o:  ascertaining  whether  the  apiculi  of  the  two  valves  are  opposite, 
except  in  a  single  instance — a  large  cylindrical  frustule  of  C. 
mirificus  mounted  in  zonal  view,  and  in  this  the  apiculi  are 
opposite. 

In  C.  gigas  the  apiculi  are,  if  present,  obscure,  and  I  can  find 
no  marginal  indications  of  them.  C.  diorama  and  allied  forms, 
however,  often  classed  as  varieties  of  C.  gigas,  have  the  border 
distinctly  marked  with  two  apparent  notches  as  in  C.  perforatus. 
C  concinnus  has  distinct  apiculi,  and  many  specimens  have  in 
addition  crescentic  processes  outside  the  valve,  partly  surrounding 
the  point  at  which  the  apiculi  originate.  These  valves  are  known 
as  Eupodiscus  Jonesianus  Greville  (E.  commutatus  Grunow),  but 
I  do  not  think  they  have  any  claim  to  rank  even  as  a  variety. 
They  are  abundant  in  slides  from  Ouxhaven,  mixed  indis- 
criminately with  valves  having  the  internal  apiculi  only. 

While  several  forms  besides  those  which  I  can  identify  with 
the  foregoing  species  share  in  the  peculiarity  in  question,  there 
are  many  others  in  which  I  have  failed  to  detect  it.  Such  are  the 
thick  variety  of  C.  Oculus  Iridis  found  in  the  Mors  deposit,  also 
■C.  radiatus.  In  more  typical  forms  of  C .  Oculus  Iridis,  however, 
careful  search  has  disclosed  two  apiculi,  which  are  simple  bacillar 
projections  into  the  cavity  of  the  frustule. 

Apart  from  these  appendages  the  structure  of  the  border  itself 
has  in  many  cases  not  received  sufficient  attention  as  a  help  in 
classification.  Some  species  have  distinct  borders  with  markings 
quite  different  from  those  of  the  valve  generally,  others  have  the 
areolar  structure  continued  to  the  extreme  margin  without 
interruption ;  in  some  the  edge  is  turned  over,  in  others  it  is 
quite  flat,  and  frequently  the  specific  diagnosis  contains  no 
hint  of  the  character  of  the  valve  in  this  respect ;  so  that  of  two 
valves,  differing  widely  in  this  particular,  it  may  be  impossible  to 
decide  which  of  them  corresponds  with  the  specific  description. 
C.  concinnus  and  C.  centralis  may  serve  to  illustrate  this.  Both 
are  very  convex,  but  in  the  former  the  marginal  part  is  slightly 
flattened,  the  areolae  diminish  to  a  very  minute  size,  and  are 
succeeded  by  an  extremely  narrow  hyaline  border,  thinning 
away  so  as  to  show  only  a  smooth  single  contour.  In  a  typical 
C.  centralis,  on  the  other  hand,  the  valve  curves  downward  to  the 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  27 

extreme  edge,  and  the  areolae  are  of  an  appreciable  size  throughout, 
while  the  border  is  not  thinned  away,  so  that  on  focusing  the 
margin  there  is  visible  a  distinct  double  contour,  with  the  walls  of 
the  last  row  of  cellules  showing  as  coarse  transverse  striae. 

Several  species  exhibit  a  tendency  for  the  border  to  become 
wider  in  proportion  as  the  valves  are  smaller.  C.  obscurus  and 
V.  apiculatus  are  instances  of  this.  In  both  these  species  I  have 
traced  a  series  down  to  forms  with  wide  borders,  which  are 
only  to  be  distinguished  with  difficulty  from  C.  marginatus. 
In  Nottingham  and  other  American  deposits  such  forms  of 
C  apiculatus  are  common,  and  one  of  them  figured  by  Schmidt 
(PI.  62,  f.  11,  12)  has  been  referred  by  Rattray  to  C.  marginatus. 

In  several  species  of  the  Radiati  the  angles  of  the  areolae  often 
tend  to  become  thickened,  so  that  in  a  certain  focus  there  appears 
to  be  a  bead  at  each  angle.  This  feature  has  no  specific  im- 
portance, and  I  agree  with  Rattray  that  the  presence  at  each 
a,ngle  of  a  distinct  spine,  as  occasionally  found,  is  of  no  greater 
consequence. 

I  have  already  referred  to  the  close  affinity  which  exists 
between  the  Excentrici  and  the  Fasciculati,  e.g.  between  C.  ex- 
centricus  and  C.  subtilis.  Grunow  mentioned  this  affinity,  but 
Rattray  says  that  it  is  remote.  Grunow's  view  is  undoubtedly 
correct.  In  a  typical  G.  excentricus  there  is  a  central  cellule, 
and  surrounding  it  a  circle,  generally  of  seven.  Each  of  these 
seven  is  the  centre  of  an  arcuate  line  of  cellules,  extending  to 
the  margin  on  either  side,  behind  which  is  a  succession  of  similar 
arcuate  series,  so  that  the  whole  of  the  cellules  may  be  regarded 
as  forming  seven  fascicles,  crossing  each  other  symmetrically,  so 
that  no  division-lines  exist,  and  for  the  most  part  each  cellule 
will  form  part  of  three  different  fascicles.  In  C.  subtilis  and 
C.  symbolophorus  the  number  of  fascicles  is  greater,  and  the 
divisions  between  them  more  abrupt,  especially  in  the  central 
part  of  the  valve,  so  that  the  fasciculation  is  more  manifest,  but 
even  in  these  forms  the  fascicles  blend  towards  the  margin  in  the 
same  way  as  those  of  C.  excentricus.  I  have  seen  a  frustule  of 
the  latter  species  in  which  one  valve  was  normal,  while  the 
other  was  far  more  finely  marked,  and  was  as  distinctly 
fasciculate  as  C.  subtilis. 

I  should  mention  that  the  C.  subtilis  referred  to  is  Grunow' 
typical  form,   which  is  quite   different  from    Rattray's,    though 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

that  observer  quotes  Grunovv  as  his  authority.  He  describes 
C.  subtilis  as  apiculate,  and  differentiates  other  species  from  it 
by  the  absence  of  apiculi.  Yet  Grunow  says  expressly  that 
C.  subtilis  is  non-apiculate.  "  Der  Ausgangspunkt  fiir  alle  diese 
Formen  ist  der  stachellose  C.  subtilis  (Ehr.  partim),  Gregory, 
Grunow  "  (Diat.,  F.-Josef  Land,  p.  81).  This  form,  which  is  similar 
to  C.  symbolophorus,  but  without  the  stellate  markings  at  the 
centre,  also  agrees  well  with  Rattray's  own  account  of  Ehren- 
berg's  original  species.  It  is  not  common,  and  Yan  Heurck 
figures  it  from  guano,  not  finding  it  in  European  gatherings. 
But  Peragallo,  like  Rattray,  though  claiming  to  follow  Grunow's 
authority  for  the  type,  has  figured  and  described  a  totally  different 
form — an  apiculate  variety. 

Actinocyclus. — The  excessive   multiplication  of   specific    names 
which  encumbers  the  Coscinodisci  has  not  been  carried  out  to  a 
corresponding  extent  in  the  much  smaller  group  of  the  Actino- 
cycli    (ignoring,  of    course,    Ehrenberg's    multitudinous    pseudo- 
species)  ;  still  there  is  no  doubt  that  an  undue  regard  for  certain 
points  of  structure  has  led  to  the  establishment  of  several  species 
on     insufficient    grounds.       Rattray's  monograph    admits    about 
seventy  species  :  Fome  of  these  have  no  claim  to  recognition,  but, 
on  the  other  hand,  I  find  that  about  fifteen   out   of  thirty-four 
species  or  varieties  which  I  possess  cannot  be  identified  with  any 
of  Rattray's  descriptions.      He  has  adopted  in  this  monograph 
the    plan  of    furnishing  extremely    long    and    minutely  detailed 
descriptions,  a  method  which  renders  identification  more  certain 
when  one  is  dealing  with  the  precise  form   described,   but  does 
not  allow  for  the  variations  which  constantly  present  themselves 
even  in  a  single    gathering.      In  fact,   as   I    have  remarked  in 
reference   to    Coscinocliscus,   many  of  these  are  not  descriptions 
of  species,   but  of   individual    diatoms.     Mr.   Rattray   uses   five 
places  of  decimals  to  express  the  fraction  of  a  millimetre  which 
corresponds    to    the    diameter    of    a    pseudo-nodule  !      Of    what 
possible  use  can  such  measurements  be  when  applied  to  structures 
so  notoriously  variable  ? 

Before  discussing  the  range  of  variation  in  the  genus,  and 
as  I  shall  refer  repeatedly  to  the  commonest  species — A.  Ehren- 
bergii — I  must  premise  that  I  use  that  name  in  the  sense  in 
which  it  is  used  by  Ralfs  himself,  and  by  Yan  Heurck,  Grunow, 
Peragallo,  and,  so  far  as  I  know,  by  all  other  observers  except 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  29 

Rattray,  who  has  unaccountably  assigned  the  name  to  an  entirely 
different  form,  while  describing  the  true  A.  Ehrenbergii  as 
A.  moniliformis  Ralfs.  A.  Ehrenbergii  was  described  by  Ralfs 
from  his  own  knowledge,  while  A.  moniliformis  was  merely  a 
name  given  by  him  to  certain  forms  from  Oran  and  Virginia, 
which  he  had  not  seen,  but  which  he  judged  from  Ehrenberg's 
tigures  to  be  distinct,  the  distinction  consisting  in  the  division 
of  A.  Ehrenbergii  into  compartments  by  double  lines,  while 
A.  moniliformis  was  divided  by  single  ones.  There  is  really  no 
difference,  except  such  as  depends  on  the  size  of  the  valves  and 
the  number  of  the  fasciculi.  In  small  valves,  containing  few 
fascicles,  the  interfasciculate  rays  form  a  wide  angle  with  the 
other  series,  and  are  therefore  very  marked ;  and  these  are  the 
"  single  series  of  dots  "  referred  to  by  Ralfs.  In  large  valves 
the  fascicles  are  numerous  and  narrow,  so  the  interfasciculate 
rays  form  a  small  angle  with  the  other  series,  which,  stopping 
short  at  various  points,  leave  a  double  row  of  subulate  blank 
spaces  along  the  sides  of  each  primary  or  interfasciculate  ray, 
and 'these  subulate  areas  constitute  the  "double  lines"  of  Ralfs. 
That  the  small  valves  from  Oran  and  Virginia,  and  the  large 
ones  from  Cuxhaven,  etc.,  are  one  and  the  same  species  is  fully 
recognised,  however,  by  Rattray,  but  he  names  them  A.  monili- 
formis. To  any  one  who  reads  carefully  Ralfs'  account  of 
A.  Ehrenbergii  there  can  be  no  possible  doubt  as  to  the  identity 
of  the  species.  It  was  established  specially  to  include  the 
many-rayed  forms  described  by  Ehrenberg,  which  mostly  occur 
at  Cuxhaven  ;  Ralfs  also  states  that  it  is  "  very  fine  in  Ichaboe 
guano,"  and  that  most  of  the  forms  can  be  obtained  therein  ; 
and  further,  that  it  is  "  common,  both  recent  and  fossil."  One 
species,  and  only  one,  answers  perfectly  to  this  description, 
namely,  that  which  Rattray  calls  A.  moniliformis,  but  which, 
in  its  larger  forms,  at  least,  has  been  recognised  by  observers 
generally  as  A.  Ehrenbergii.  Rattray  might  have  been  justified 
in  preferring  the  name  of  A.  moniliformis  on  the  ground  of 
priority,  but  he  has  failed  to  perceive  that  the  forms  which  he 
has  placed  under  it  are  no  other  than  the  A.  Ehrenbergii  of 
authors,  and  has  inexplicably  assigned  the  name  A.  Ehrenbergii 
to  a  species  (or  variety)  differing  entirely  from  that  described 
by  Ralfs.  It  is  not  found  at  Cuxhaven,  nor,  so  far  as  is  known, 
in  Europe  at  all ;    it  is  far  from  being    common,  either  recent 


30  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

or  fossil,  and  it  is  not  found  in  Ichaboe  guano.  It  is  dis- 
tinguished from  the  true  A.  Ehrenbergii  by  its  concentrically 
undulated  valves,  by  its  strong  iridescence,  and  by  its  sharply 
defined  zones  of  colour  under  low  powers.  Its  granules  are 
also  more  closely  and  regularly  arranged,  forming  over  the 
greater  part  of  the  valve  a  very  regular  areolation.  To 
distinguish  it  from  the  true  A.  Ehrenbergii  I  propose  for  it 
the  specific  name  of  A.  rex.  I  have  only  found  it  in  the 
deposits  of  Nottingham,  Curfield,  Atlantic  City,  and  Lyons 
Creek.  Rattray's  localities  are  necessarily  unreliable,  so  far 
as  they  are  given  on  the  authority  of  other  observers,  of  whom 
some  at  least  (Ralfs,  for  example)  were  referring  to  the  true 
A.  Ehrenbergii,  and  not  this  form  at  all. 

Rattray's  description  of  this  species,  however,  requires  amend- 
ment, especially  as  regards  the  contour  of  the  valve.  He  says- 
that  large  valves  have  the  centre  depressed,  and  two  concentric 
elevated  zones  between  the  centre  and  the  border,  while  small 
valves  have  the  centre  depressed,  and  are  convex  between  it  and 
the  border.  This  is  correct  so  far  as  some  of  the  valves  are 
concerned,  but  in  others  the  surface  elevations  and  depressions 
are  in  the  opposite  order.  Thus  in  large  valves  the  centre  is 
convex,  and  there  is  one  elevated  zone  between  it  and  the  border^ 
Evidently  the  frustule  is  concentrically  undulated  as  a  whole, 
the  depressions  of  one  valve  corresponding  to  the  elevations  of 
the  other.  So  in  the  case  of  the  small  valves  with  depressed 
centre,  others,  evidently  their  counterparts,  have  the  centre 
convex.  Some  of  the  valves  in  my  slides  are  0*20  mm.  in  diameter, 
Rattray's  maximum  being  0*17. 

The  largest  European  species  is,  according  to  Rattray,  A.Ralfsiir 
of  which  I  have  not  seen  specimens  agreeing  entirely  with 
Peragallo's  description  of  the  type  ;  but  among  the  forms  of 
A.  Ehrenbergii  abundant  in  slides  from  Cuxhaven  and  Ichaboe 
guano  are  many  which  agree  with  that  description  in  the 
arrangement  of  the  fasciculi  and  subulate  areas,  though  not  in 
the  brilliant  appearance,  the  very  large  pseudo-nodule,  nor  the 
concentric  arrangement  of  the  granules.  One  has  only  to  read 
the  descriptions  of  Ralfs,  Yan  Heurck,  Rattray  and  Peragallo 
to  see  that  no  two  of  these  observers  agree  as  to  the  respective 
characters  of  A.  Ralfsii  and  A.  Ehrenbergii,  which  is  nob  sur- 
prising   if,    as    Peragallo    states,    every   intermediate    gradation 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  31 

exists  between  the  two  types.  This  agrees  with  the  views 
expressed  by  Grunow,  Lagerstedt,  and  others ;  it  would  seem, 
therefore,  that  Peragallo  is  justified  in  treating  A.  Ehrenbergii 
as  at  most  a  variety  of  A.  Ralfsii. 

Most  species  of  A.ctinocyclus  have  the  markings  arranged  on 
the  same  general  plan  as  A.  Ehrenbergii.  The  surface  of  the 
valve  is  divided  into  cuneate  areas  by  a  number  of  moniliform 
series  of  granules  (the  interfasciculate  rays),  which  radiate  from 
the  centre,  or  near  it,  to  the  marginal  zone.  Each  cuneate  area 
contains  a  fascicle  of  similar  moniliform  series,  but  only  the 
central  one  is  strictly  radial,  and  all  the  others  are  parallel 
with  it ;  and  as  they  all  stop  short  of  the  interfasciculate  rays 
they  are  necessarily  shorter  as  they  approach  these  rays.  The 
great  difference  in  the  aspect  of  the  valves  dependent  on  the 
small  or  large  number  of  fascicles  has  already  been  mentioned. 
In  the  largest  valves,  where  they  are  most  numerous,  they  are 
so  narrow  that  they  consist  of  very  few  series  of  granules,  and 
the  angles  which  they  form  with  the  interfasciculate  rays  are  so- 
small  that  at  first  sight  it  might  appear  that  all  the  series  are 
« truly  radial.  Such  is  the  structure  in  the  largest  valves  of 
A.  Ralfsii,  A.  Ehrenbergii,  A.  Barklyi,  etc.,  but  the  markings  are 
just  as  truly  fasciculate  as  in  the  smallest  form's,  though  the 
fasciculi  are  not  so  patent.  No  amount  of  variation  of  the 
kind  described,  therefore,  is  in  itself  of  importance  in  classification. 
But  great  irregularities  in  the  arrangement  of  the  markings 
prevail,  and  there  is'  perhaps  no  other  genus  in  which  valves 
of  one  and  the  same  species  present  such  different  aspects. 
While  one  valve  may  have  the  interfasciculate  rays  very  distinct, 
all  starting  from  a  circular  central  ring  of  granules,  and  all  the 
series  well  defined,  the  next  may  present  at  first  sight  a  very 
different  aspect,  owing  to  the  denseness  of  the  granulation,  and 
in  yet  another  much  of  the  appearance  of  regularity  may  be 
lost  owing  to  its  sparseness.  This  is  especially  noticeable  in  the 
centre  of  the  valve,  where  there  may  be  a  regular  area,  with 
perhaps  a  few  granules  in  the  centre,  while  in  other  cases  there 
may  be  no  definite  area  at  all.  Usually  the  interfasciculate  rays 
stop  short  at  a  little  distance  from  the  centre,  but  in  the  small 
valves  of  A.  Ehrenbergii  from  Oran,  as  Mr.  Rattray  points  out, 
they  cross  each  other.  Another  point  of  variation  is  the  width 
of  the  blank  areas  along  the  sides  of  the  interfasciculate  rays. 


32  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

Jl,  fasciculatus  Castracane  is  distinguished  by  the  notable  width 
■of  these  areas,  but  the  character  is  of  no  specific  importance. 
A,  Ehrenbergii  often  exhibits  such  areas,  and  I  have  seen  them 
in  one  valve  while  the  other  in  the  same  frustule  showed 
scarcely  a  trace  of  them.  They  may  even  exist  on  only  a  part 
■of  a  valve.  So  far  as  Castracane's  figures  show,  there  is  nothing 
to  distinguish  his  species  from  A.  Ehrenbergii. 

A  frequent  phenomenon  in  the  genus  is  the  occurrence  of 
regular  or  irregular  blank  areas  crossing  the  rows  of  puncta, 
•often  in  a  sub-concentric  fashion,  and  A.  crassus  is  a  form  in 
which  the  apparent  irregularity  of  the  markings  from  this  cause 
has  been  made  a  ground  for  specific  distinction.  Yet  both  Van 
Heurck  and  Peragallo,  who  admit  the  species,  show  by  their 
figures  that  the  markings  are  as  in  A .  Ehrenbergii,  except  in  so 
far  as  the  granules  ard  obliterated  over  certain  irregularly  sub- 
concentric  areas.  I  find  nothing  here  to  warrant  the  separation 
•of  the  form  as  a  distinct  species. 

The  interfasciculate  rays  are  also  liable  to  interruptions,  and 
Castracane  has  described  a  species — A.  complanatus — in  which 
they  are  said  to  be  wanting,  though  the  valve  is  of  the  ordinary 
fasciculate  type.  I  greatly  doubt  the  correctness  of  this,  not 
merely  on  a  priori  grounds,  but  owing  to  Rattray's  identification 
of  this  species  with  the  form  distributed  by  Moller  as  A.  Ralfsii. 
Now  the  "  A.  Ralfsii1'  of  my  Typen-Platte  is  simply  one  of  the 
forms  of  A.  Ehrenbergii  in  which  the  fasciculation  is  similar  to 
that  of  A.  Ralfsii,  and  which  abound  in  Cuxhaven  and  Ichaboe 
guano  material.  The  interfasciculate  rays  are  certainly  not 
wanting,  though  doubtless  obscure  and  irregular  in  parts.  Many 
otherwise  similar  valves  occur  in  which  there  is  no  noticeable 
irregularity  of  these  rays. 

The  general  aspect  of  the  valve  depends  largely  on  the  position 
and  distance  of  the  granules  relatively  to  the  others  in  the  same 
und  adjacent  rows  of  the  fascicle.  In  A.  Barklyi  the  granules  of 
each  row  are  very  close  to  each  other,  but  not  so  close  to  those 
of  the  next  rows ;  the  rows  therefore  remain  distinct  from  each 
other  even  to  the  border.  In  A.  Ralfsii  type  and  var.  sparsus 
the  granules  of  adjacent  rows  are  mostly  side  by  side,  so  that 
they  form  straight  lines  crossing  the  fascicles,  thus  having  as  a 
whole  a  sub-concentric  disposition  ;  they  are  also  distinctly 
separated  from  each  other.     In  A.  Ehrenbergii  there  is   much 


W.    M.    BALE    ON    SOME    OF   THE    DISCOID    DIATOMS.  33 

variation,  the  granules  often  forming  irregular  zigzag  lines 
crossing  the  fascicles;  generally,  however,  the  tendency  is  for 
the  granules  of  adjacent  series  to  alternate  with  each  other,  and 
also  to  be  somewhat  crowded,  so  as  to  form  a  quincuncial 
arrangement,  which  in  any  case  prevails  towards  the  border. 
In  A.  rex  the  alternate  arrangement  is  much  more  pronounced, 
and  as  the  granules  are  crowded  equally  all  round  the  markings 
form  a  very  regular  areolation  over  the  greater  part  of  the 
valve. 

The  appearance  of  the  granules  themselves  varies  remarkably 
in  the  same  species.     In  A.  Ehrenbergii  some  valves  show  them 
in  the  best  focus  as  minute,  dark,  sharply  defined  circles,  while  in 
others  they  are  more  pearly,   and  show,  much  more  readily,  a 
central    black    spot.      When    crowded,    especially    towards    the 
border,   they  form  a  distinct  areolation.     In  A.  rex  the  latter 
type  predominates,  but  near  the  centre  the  granules  are  more 
pearly.     In   A.   Barklyi   and   A.  ellipticus   they   vary  much   as 
in  A.  Ehrenbergii.     And  in  all  these  species  they  appear  some- 
times as  dark,  well-defined  puncta.     Peragallo  has  figured  a  form 
which  he  calls  A.  nebulosus,  and  which  is  practically  a  hyaline 
valve  of  A.  Ehrenbergii  with  fine  puncta  instead  of  granules,  also 
a  corresponding  form  with  the  puncta  arranged  like  the  granules 
of  a  typical  A.  Ralfsii.     He  thinks  these  valves  are  probably  the 
result  of  cleavage,  of  the  correctness  of  which  opinion  I  think 
there  can  be  no  doubt.     Corresponding  forms  of  A.  Barklyi  are 
found  in  hundreds  in  slides  of  that  species,  often  so  delicate  and 
colourless  that  they  become  invisible  on  a  slight  alteration  of  the 
focus.     How  many   layers  has  a  valve  of   A.  Barklyi%     When 
manipulating   one   under   the   microscope   I   saw  it   divide   into 
three,  one  extremely  thin  and  hyaline,  and    another  somewhat 
thicker,   but   still   less   robust    than    the    main   disc.     Here  the 
question  of  colour  comes  in  for  consideration,  for  it  is  probable 
that  the  colour  as  well  as  the  appearance  of  the  granules  depends 
more  or  less  on  the  "  state  "  of  the  valve — whether  it  consists  of 
more  than  one  plate  for  instance,    or   whether  the  two  plates 
include  a  film  of  air  between  them.     A.  rex  is  the  most  brightly 
coloured  form  I  have  seen,  having  the  colours  in  sharply  defined 
zones.     A.  Ehrenbergii  is  usually  blue,  green,  purple,  or  brown, 
often  showing  more  than  one  colour,  but  not  in  sharp  zones.     A . 
Barklyi  varies  much  in  the  same  way,  but  is  exceptionally  liable 
Journ.  Q.  M.  0.,  Series  II.— No.  72.  3 


34  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

to  exhibit  a  dark,  semi-opaque  aspect.  But  all  these  species 
usually  include  forms  of  the  same  size,  contour  and  arrangement 
of  markings,  but  of  a  soft  brown  colour,  uniform  throughout 
or  nearly  so,  and  generally  with  fine  punct'a.  Are  these  complete 
valves,  or  secondary  plates,  or  primary  plates  from  which  the 
secondary  ones  have  been  detached  ?  Some  of  these  brown  discs 
have  the  silex  of  the  subulate  areas  so  thickened  as  to  appear 
black  under  a  low  power.  Valves  of  A.  Ehrenbergii  with 
sharply  defined  granules  and  clear,  distinct  subulate  areas  mostly 
appear  blue  under  low  powers,  with  the  subulate  spaces  white. 
Others,  such  as  that  described  above,  from  Holler's  Typen-Platte, 
are  more  commonly  green  or  purple,  and  show  no  white  streaks, 
though  having  large  subulate  areas,  the  substance  of  the  valve 
itself  appearing  to  have  a  dusky  tint.  The  bright  colours  of 
these  species  can  only  be  seen  when  dry  or  mounted  in  balsam 
or  a  similar  medium,  while  in  water  they  are  colourless. 

No  other  diatom  known  to  me  presents  such  endless  variety 
of  marking  as  A.  Barklyi,  and  occurring,  as  it  does,  in  such 
profusion,  it  is  especially  suitable  for  a  study  in  variation.  This 
diatom  is  of  interest  as  being  probably  the  first  to  be  named  in 
Australia,  it  having  been  described  by  Dr.  Coates  in  the  Trans- 
actions of  the  Royal  Society  of  A^ictoria  for  1 860,  under  its 
present  name.  Rattray  incomprehensibly  calls  it  "  Actinocyclus 
Barklyi  (Ehr.)  Grun.,"  though  he  knew  that  it  was  named  by 
Coates,  and  not  by  either  of  the  authors  cited.  He  quotes  a 
reference  to  it  in  the  Q.  J.  M.  S.  for  1861  (wrongly  quoted  as 
"Plate  CXXXVIII."  instead  of  "Page  138  "),  but  does  not  refer 
to  Coates'  original  description.  It  is  distributed  by  Moller  under 
the  name  A.  dubius  Grunow.  It  is  one  of  the  largest  of  the 
genus  (perhaps  the  largest),  specimens  in  my  slides  attaining  a 
diameter  of  0*24  mm.,  or  more  than  double  the  maximum  size 
assigned  to  it  by  Rattray. 

In  normal  valves  the  fasciculi  are  arranged  much  as  in  A. 
Ralfsii,  but  great  variety  exists  in  the  denseness  or  otherwise  of 
the  granules,  which,  as  in  A.  Ehrenbergii,  also  vary  greatly  in 
sharpness.  But  it  is  in  individual  departures  from  the  normal 
arrangement  that  the  tendency  to  variation  exhibits  itself  in 
such  an  extraordinary  degree.  In  many  cases  the  markings  are 
interrupted  at  a  uniform  distance  from  the  centre,  so  as  to  form 
a  ring,  and  several  such  concentric  rings  may  exist  on  one  valve, 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  35 

dividing  it  into  zones.  Sometimes  the  markings  are  denser  on 
one  of  these  zones  than  elsewhere.  Very  often  the  zones  form 
hyaline  bands  on  which  the  granules  are  wanting,  and  the 
structure  may  be  further  complicated  by  the  addition  of  radial 
hyaline  bands,  e.g.  two  hyaline  zones  may  be  joined  by  a  number 
of  equidistant  radial  hyaline  areas  so  that  the  space  between 
them  is  divided  into  a  circular  series  of  sub-rectangular  com- 
partments ;  or  a  broad  circular  zone  may  be  filled  with  hyaline 
patches  of  all  sorts  of  irregular  shapes.  The  radial  series  of 
granules  may  be  all  curved  in  a  spiral  fashion  (a  variation 
which  also  occurs  in  C.  Ehrenbergii),  and  I  have  specimens  in 
which  the  central  portion,  as  far  as  the  first  circular  interruption, 
has  the  moniliform  series  all  contorted  in  the  most  extraordinary 
manner.  As  in  A.  rex,  etc.,  the  subulate  areas  may  be  either 
darker  or  lighter  than  the  rest  of  the  valve.  There  may  be  a 
small  central  area,  or  the  whole  centre  of  the  valve  may  be 
sparsely  and  irregularly  marked. 

I  find  that  in  some  slides  concave  and  convex  valves  are  mixed 
about  equally,   leading    to    the    conclusion    that    the   two    forms 
represent  opposite  valves,  as  in  A.  rex,  but  in  other  gatherings 
I  find  many  concave  valves  to  every  convex  one.     Rattray  de- 
scribes the  valves  as  flat  in  the  centre  and  otherwise  convex,  but  in 
numerous  cases  the  convexity  (or  concavity)  is  uniform  throughout. 
Asteromphahis. — In  this   genus  the   lines  which    radiate  from 
about  the  head  of   the  centro-lateral  area  to  the  apices  of  the 
areolate  compartments  have    been  assigned   too  much   value  in 
classification.     Whether  they   originate   from   a  single  point,  or 
whether  they  bifurcate,  is  absolutely  immaterial,  and  the  presence 
of  geniculate  bends  in  their   course  is,  in  some  species  at  least, 
equally  unimportant.     A.  Hookeri,  which  is  not  rare  in  one  of  the 
"Challenger"  Antarctic  soundings,  illustrates   this.     The  forms 
with   six,  seven,   eight   and  nine   rays,  which   represent  four   of 
Ehrenberg's    "species,"    also    a   ten-rayed   form,   occur  in    slides 
which    I    have    prepared    from    this    material,    and    1    find    the 
geniculations   of  the  radial   lines   very   marked  in   some   valves, 
while  others  show  no  trace  of  them  ;  others  again  exhibit  a  mixed 
condition.     A  good  deal  seems  to  depend  on  the  size  of  the  valve, 
the  geniculate  lines  being  most  common  in  the  smaller  ones. 

Certain    species    are    subject    to    variation    in    the    outline. 
A.  Cleveanus,  as  figured  by  Schmidt,  has  a  rather  narrow  ovate 


36  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

form,  but  in  mud  from  Manila  it  has  a  broader   outline,  and 
I  found  one  valve  perfectly  circular. 

Actinoptychus. — This  genus  is  distinguished  by  its  valves  being 
divided  into  six  or  more  radial  cuneate  compartments,  which  are 
alternately  raised  and  depressed,  the  markings  also  differing  (in 
normal  valves)  on  the  elevated  and  depressed  areas.     On  what 
we  may  call,   for    want    of    a    better   term,    the   primary   areas 
{Hauptfelder  of  Schmidt),  the  coarse  markings  are  usually  more 
robust,  and  often  of  different  form,  from  those  on  the  secondary 
areas    (Nebenf elder   of    Schmidt)  ;    further,  the    primary    areas 
usually  bear  a  tooth  or  process  near  the  margin,  with,  in  some 
species,  a  radial  line  connecting  it  with  the  umbilicus ;  while  the 
secondary  areas  sometimes  terminate  in  a  submarginal  hyaline 
band,  which  is  not  found  in  the  primaries.     The   fine   striation 
also  is  commonly  different  on  the   two   sets   of    compartments. 
The  striation  is  generally  fairly  uniform  within  the   limits  of 
a  species,  but  the  secondary  markings,  consisting  of  hexagonal 
or  irregular  reticulation,  or  systems  of  branching  veins,  is  most 
variable  in  its  distinctness,  and  is  often  wanting.     When  this 
occurs  it  is  generally  assumed  to  be  the  result  of  the  detachment 
of  the  separate  layer  of  the  valve  which  is  thus  marked,  but  in 
view   of   the   fact   that   different   valves   exhibit   every   possible 
degree  of  obsolescence  of  these  markings,  I  have  no  doubt  that 
in  many  cases  they  have  not  been  developed. 

Among  the  characteristics  to  which  too  much  importance  has 
been  attached  in  classification  are — the  number  of  areas,  the 
substitution  of  primary  for  secondary  areas  (so  that  all  the  areas 
are  alike),  the  presence  or  absence  of  the  secondary  markings, 
also  of  the  lines  connecting  the  umbilicus  with  the  processes,  and 
the  presence  of  small  variations  in  the  striation.  The  adoption 
of  these  purely  artificial  distinctions  has  led  not  only  to  the 
undue  multiplication  of  specific  names,  but,  what  is  worse,  to  the 
lumping  together  of  forms  which  are  by  no  means  closely  related. 
In  several  species  there  are  six  areas,  a  number  which  is 
rarely,  if  ever,  departed  from.  Such  are  the  forms  composing 
the  group  of  which  A.  boliviensis  is  typical.  In  the  majority  of 
species  there  is  no  constant  number;  for  example  the  beautiful 
A.  Heliopelta,  valves  of  which  usually  have  six,  eight,  ten,  or 
twelve  areas  (constituting  Ehrenberg's  four  species  of  Heliopelta), 
while  more  rarely  there  are  fourteen  or  sixteen.     A.  undulatus, 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  37 

the  most  widely  distributed  species,  is  found  in  most  localities  with 
six  areas  only,  yet  in  some  Calif ornian  deposits  it  occurs  freely 
with  up  to  eighteen  areas,  possibly  more. 

A.  undulatus  is  a  species  which  well  illustrates  the  tendency  of 

the  genus  to  vary  in  several  directions,  but  the  variations  are 

so   numerous   and   so   closely  linked,  and  their  relationships  so 

obvious,  that  they  have  not  been  made  the  basis  of  so  many 

pseudo-species  as  might  have  been  expected.     I  have  noted  about 

twenty-five   forms  sufficiently  distinct  to  admit  of   their  being 

separated  for  convenience  of  cataloguing,  but  few  of  them  are  so 

characteristic    as  to   constitute    definite  varieties.     In    forms  of 

average  size,  which  may  be  considered  fairly  typical,  the  secondary 

markings   are    commonly   about   four  in  O'Ol  mm.,  while  in  the 

var.   microsticta  of   Grunow,   there  may  be  about  seven,  and  in 

large  forms  like  forma  maxima  Schmidt,  there  are  only  one  and 

a   half  to   two.     The   reticulation    may   be    either  hexagonal  or 

irregular,  robust  or  faint,  and  sometimes  entirely  wanting.     The 

sub-marginal  processes  are  said  to  be  sometimes  absent ;  in  fact, 

both  W.  Smith  and  Yan  Heurck  appear  to  regard  this  condition  as 

typical,  but  I  have  not  seen  specimens  without  some  trace  of  them. 

(The   obsolete   genus    Omphalopelta   comprised   the   valves   with 

processes.)     The  processes  may  be  very  small,  appearing  merely 

as  a  slight  thickening  of  the  border,  or  may  be   placed  a  little 

farther    in,    presenting    a    somewhat    irregular    keyhole-shaped 

aspect.     In    many    forms   the   secondary   areas    have    on   their 

margin  a  small  hyaline  patch  in  the  corresponding  position   to 

that  occupied  by  the  processes  in  the  primaries.     On  both  sets 

of  areas  the  outermost  portion,  immediately  adjoining  the  margin 

proper,  usually   bears   radial   lines,   being   continuations  of   the 

boundaries  of  the  last  row  of  secondary  markings,  which,  like  the 

secondary  markings  generally,  are   most  robust  on  the  primary 

areas.     The  rim  may  be  smooth,   or  may   have   few    or   many 

minute  apiculi  scattered  over  it.     The  puncta  which  compose  the 

striae  of  the  primary  areas  are  arranged  in  quincunx,  so  that  the 

striation  is  the  same  as  in  Pleurosigma  angulatum,  but  those  of 

the  secondary  areas  form  two  sets  of  diagonal  striae  cutting  each 

other  at  right  angles,  as  in  P.  formosum.     Schmidt  describes  as 

A.   biformis  valves  in   which  these  two  sets  of    striae  meet   at 

rather  less  than  a  right  angle,   so  that  a   third  set  is   visible, 

closer  than  the  other  two,  and  crossing  the  area  transversely. 


38  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

Some  valves  which  I  have  seen  with  this  character  were  in  all 
other  respects  similar  to  normal  valves  of  A.  undulatus,  among 
which  they  occurred,  and  I  see  nothing  to  justify  their  separation, 
the  slight  divergence  from  the  rectangular  arrangement  of  the 
striae  being  no  more  than  is  often  found  in  P.  formosum.  Some- 
times the  striae  meet  at  more  than  a  right  angle,  so  that  the 
third  set  is  radial  instead  of  tangential.  If  Schmidt's  species 
were  accepted,  this  should  make  another  species  !  The  striae  are 
sometimes  nearly  or  quite  obliterated  on  small  patches  at  the 
outer  angles  of  the  secondary  areas,  and  occasionally  along  the 
margins  ;  in  some  forms  again  they  are  wanting  or  represented 
only  by  a  few  scattered  puncta  on  a  great  part  of  those  areas. 
The  umbilicus  varies  greatly  in  size,  and  may  be  either  hexagonal 
or  may  have  three  concave  sides.  Much  variation  exists  in  the 
extent  to  which  the  areas  are  inflated,  or,  in  other-  words,  in  the 
depth  of  the  undulations. 

A  consideration  of  the  variations  of  this  diatom  will  show  how 
many  features  there  are  which,  met  with  in  isolated  forms,  may 
lead  to  the  undue  multiplication  of  species. 

In  several  species,  perhaps  in  the  genus  generally,  there  is 
a  tendency  to  produce  valves  in  which  the  secondary  areas  or 
"  Nebenfelder  "  are  replaced  by  primary  ones  or  "  Hauptfelder," 
so  that  all  the  areas  become  alike,  except  in  their  elevated  or 
depressed  condition.  Van  Heurck  has  figured  such  a  form  of 
A.  undulatus — the  forma  sexapjiendicidata,  which  he  says  may 
co-exist  in  the  same  frustule  with  the  normal  form.  He  refers 
only  to  the  presence  of  a  process  on  every  area,  and  does  not 
mention  that  the  areas  are  otherwise  modified,  which,  however, 
I  have  always  found  to  be  the  case.  Other  varieties  of 
A.  undulatus  exhibit  the  same  tendency  ;  thus  the  large  forma 
maxima  found  in  the  Nottingham  deposit  is  accompanied  by  its 
"forma  sexappendiculata"  as  also  is  an  equally  large  variety 
which  only  differs  from  it  in  the  strongly  apiculate  margin.  In 
all  these  cases  the  compartments  all  correspond  exactly  with  the 
normal  primary  areas,  both  in  the  striation  and  the  coarser 
secondary  markings.  There  may  possibly  be  varieties  with  this 
as  the  usual  condition,  as  I  have  found  one  or  two  such  forms 
sparsely  distributed  in  material  where  I  noticed  no  typical  valves 
to  which  they  might  correspond. 

In  A.  Heliopelta  also  valves  are  formed  in  which  all  the  areas 
are  alike,  instead  of  alternately  primary  and  secondary. 

It  is  to  be  noted  that  in  all  species  where  this  phenomenon 


W.    M.    BALE    ON    SOME    OF   THE    DISCOID    DIATOMS.  39 

occurs  it  is  always  the  primary  area,  with  its  process,  which  is 
duplicated ;  we  never  see  valves  with  all  the  areas  alike  and 
having  the  distinctive  markings  of  the  secondary  ones. 

Notwithstanding  that  it  has  been  recognised  that  in  A.  undu- 
latus  the  variation  in  question  has  no  specific  importance,  being 
found,  in  fact,  in  frustules  otherwise  normal,  a  parallel  variation 
in  other  cases  has  been  made  a  ground  for  the  foundation  of  new 
species,  even  by  observers  as  recent  as  Grunow  and  Schmidt. 
Such  instances  are  A.  Janischii  Grun.,  which,  as  I  shall 
demonstrate,  is  only  a  state  of  A.  splendens,  and  A.  Molleri 
Grun.,  which  is  a  form  of  A.  adriaticus  Grun.  Van  Heurck  says 
of  A.  Janischii  that  it  "  se  distingue  de  toutes  les  autres  especes 
du  genre  en  ce  que  la  valve  a  toute  juste  moitie  autant 
d'ondulations  que  de  divisions,  de  facon  qu'une  elevation  n'est 
suivie  d'une  autre  elevation  que  pres  da  deuxieme  appendice 
suivant.  Une  espece  analogue  mais  plus  petite  est  V  A.  Jfolleri 
d'Adelaide,  qui  se  distingue  en  outre  par  sa  structure  plus 
delicate  et  l'absence  d'une  ligne  mediane."  This  is  simply 
equivalent  to  saying  that  each  area,  instead  of  each  alternate 
area,  bears  a  process,  and  it  is  surprising  that  the  writer  did  not 
observe  that  the  character  referred  to  as  so  exceptional  was  no 
other  than  he  has  figured  in  the  same  plate  in  the  forma 
sexappendicidata  of  A.  undulatus. 

A.  glabratus  Grunow  and  A.  Janischii  Grunow  are,  in  part  at 
least,  forms  of  A.  splendens,  but  there  is  a  difference  in  the 
relationship  which  they  bear  to  that  species,  A.  glabratus 
simply  consisting  of  valves  wanting  the  secondary  markings, 
while  A.  Janischii  is  an  internal  disc.  A.  splendens  commonly 
has  a  distinct  secondary  layer  showing  more  or  less  branching 
venation,  with  the  typical  distinction  between  primary  and 
secondary  areas,  but  a  gathering  usually  includes  a  propor- 
tion of  valves  in  which  the  secondary  layer  is  wanting ;  and 
although  there  is  every  possible  gradation,  the  smooth  valves 
have  been  described  as  a  doubtful  species,  under  the  name  of 
A .  glabratus.  Also  accompanying  them  are  valves  in  which  all 
the  compartments  bear  processes,  and  to  these  the  name 
A.  Janischii  has  been  given,  Janisch  having  figured  one  of 
them  (as  Halionyx  vicenarius)  in  his  paper  on  diatoms  from 
guano.  Tn  Peru  guano  A.  splendens  is  one  of  the  commonest 
species,  and  the  typical  valves,  with  their  glabratus-iovms  and 
Janischii-iovms,  are  readily  obtained.  In  a  Cuxhaven  gathering 
I  also  find  all  three  forms  together.     And  in  a  slide  of  Thum's, 


40  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

which  contains  a  very  robust  variety,  all  three  forms  are 
similarly  associated.  In  the  valves  described  as  A.  Janischii 
the  marginal  sculpture  differs  somewhat  from  that  proper  to 
A.  splendens,  but  this  is  a  necessary  concomitant  of  the  substi- 
tution of  primary  for  secondary  areas.  In  A.  splendens,  as  in 
several  other  species,  the  secondary  areas  terminate  in  a  sub- 
marginal  hyaline  band,  which  encroaches  slightly  on  the  primary 
areas  at  each  side  of  it.  When,  however,  all  the  areas  have  the 
same  structure,  this  band  is  wanting,  all  except  the  small  portion 
which  properly  belongs  to  the  primary  areas,  so  that  a  small 
rounded  hyaline  patch  opposite  the  edges  of  the  compartments  is 
all  that  remains. 

The  relationship  between  these  forms  has  always  appeared  to 
me  obvious,  as  it  evidently  did  to  Ralfs,  who  describes  A.  splendens 
as  having  a  tooth  on  each  compartment,  or  sometimes  only  on 
alternate  compartments.  In  order  to  obtain  actual  proof  of  this, 
however,  it  occurred  to  me  to  examine  some  Peru  guano 
cleanings  which  had  furnished  numerous  slides,  but  in  which  the 
complete  frustules  of  A,  splendens,  where  they  occurred,  had  been 
left.  I  picked  out  ten  of  these  and  mounted  them  in  balsam, 
with  the  result  that  I  found  that  three  out  of  the  ten  contained 
valves  of  the  so-called  A.  Janischii,  each  being  included  in  a 
frustule  between  two  of  the  normal  valves.  In  all  cases  where  I 
have  examined  whole  frustules  of  A.  splendens  I  have  found  that 
the  two  valves  were  either  alike  in  the  number  of  areas,  or  one 
valve  had  a  pair  more  than  the  other.  Thus,  if  one  valve  had 
sixteen  areas  it  could  be  predicated  that  the  other  would  have 
fourteen,  sixteen  or  eighteen.  Where  an  internal  disc  was 
found  (A .  Janischii)  it  had  the  same  number  of  areas  as  one  of 
the  outer  valves.  In  the  slide  referred  to  one  frustule  had  the 
outer  valves  with  fourteen  and  sixteen  areas  respectively,  and  the 
internal  disc  with  sixteen ;  another  had  the  outer  valves  with 
sixteen  and  eighteen,  and  the  inner  with  eighteen ;  and  the  third 
had  twenty  throughout.  The  areas  of  the  inner  disc  have  the 
processes  rather  smaller  than  those  of  the  outer  valves,  and 
nearer  the  margin.  Though  the  inner  disc  is  usually  smooth, 
like  the  so-called  A.  glabratus,  this  is  not  invariably  the  case.  I 
have  a  specimen  covered  with  reticulations  as  distinct  as  in  the 
typical  valves. 

In  Van  Heurck's  opinion  several  genera,  as  well  as  species, 
have  been  founded  on  mere  internal  valves  of  various  species  of 
Actinoptychus  (as  also  of  Asterolampra).      Such  are  Debya  and 


W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS.  41 

Gyroptychus,  Debya  being  an  internal  disc  of  A.  undidatus,  very 
unlike  the  outer  valves,  and  found  by  Van  Heurck  inside  the 
normal  frustules.  The  A.  jjellucidus  Grunow,  figured  in  Van 
Heurck's  synopsis,  PI.  123,  fig.  1,  is,  as  will  be  obvious  to  any  one 
who  compares  it  with  the  figure  of  A.  Heliopelta  in  the  same 
plate,  merely  a  valve  of  the  latter  with  the  border  wanting  and 
the  secondary  reticulation  undeveloped.  In  a  genus-slide  by 
Thum  I  have  several  such  valves,  but  for  the  most  part  they 
retain  a  little  more  of  the  border,  showing  the  origin  of  the 
spines,  and  some  of  them  also  have  the  secondary  markings  more 
or  less  distinctly  indicated. 

In  many  marine  gatherings  from  Port  Phillip  a  form  of 
A.  adriaticus  is  found  in  great  profusion,  of  which  a  specimen  is 
figured  in  Schmidt's  Atlas,  PI.  153,  fig.  14.  It  varies  greatly  in 
the  distinctness  or  otherwise  of  the  secondary  markings,  and 
especially  in  the  presence  or  absence  or  fragmentary  condition  of 
the  narrow  radial  lines  which  in  the  typical  A.  adriaticus,  as  in 
A .  splendens,  run  outward  from  the  umbilicus,  or  near  it,  to  the 
processes.  In  most  slides  a  few  specimens  may  be  found  with  all 
the  areas  alike,  and  a  process  on  each,  and  it  is  this  form  which 
has  received  the  name  of  A.  Molleri  Grunow. 

Normally  the  areas  are  arched  at  the  ends,  as  shown  in  Van 
Heurck's  figures,  the  secondary  ones  being  shorter  than  the 
primary,  with  a  wide  hyaline  band  outside  them,  but  as  in  the 
form  called  A.  Molleri  they  are  all  primary  areas,  and  conse- 
quently of  the  same  length,  the  hyaline  band  is  reduced  to  a  small 
triangular  area  at  the  junction  of  every  two  compartments  with 
the  margin.  All  the  variations  of  marking  which  occur  in  the 
normal  valves  are  found  equally  in  this  form,  and  their  specific 
identity  is  obvious.  In  reality,  this  so-called  A.  Molleri  is  the 
true  A.  adriaticus  described  by  Grunow,  his  original  figure 
showing  a  valve  with  processes  on  all  the  areas,  and  exactly  the 
same  marginal  sculpture  as  described  above.  It  is  true  A.  Molleri 
is  supposed  to  be  without  the  radial  lines  to  the  processes,  but 
Grunow  recognised  in  his  original  description  of  A.  adriaticus 
that  these  lines  might  be  present  or  not,  in  which  he  was 
certainly  correct. 

These  radial  lines,  however  (sometimes  called  pseudo-raphes), 
appear  to  be  considered  by  Van  Heurck  as  distinguishing 
A.  adriaticus  from  A.  vulgaris,  though  he  admits  a  possible 
exception  in  A.  adriaticus  var.  pumila.  In  the  common 
Australian  form,   however,   it   is  obvious  that  the  presence  of 


42  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

these  lines  has  no  specific  or  varietal  significance  whatever. 
Almost  every  gathering  shows  valves  both  with  and  without 
them,  and  innumerable  specimens  exhibit  an  intermediate  con- 
dition, i.e.  where  the  lines  are  more  or  less  broken,  or  where  they 
are  present  on  some  of  the  primary  areas  of  a  valve  and  not  on 
others.  They  are  scarcely  ever  complete,  but  generally  stop 
short  of  the  umbilicus,  as  in  the  var.  balearica.  Valves  without 
them  are  otherwise  identical  with  those  possessing  them,  having 
exactly  the  same  range  of  variation  in  other  respects,  and  this 
applies  equally  to  the  so-called  A.  JIdlleri. 

While  reliance  on  such  characters  as  the  foregoing  leads  to  the 
improper  separation  of  allied  forms  on  the  one  hand,  it  tends  in 
other  cases  to  the  opposite  error.  Thus  several  varieties  of 
A.  glabratus  have  been  described,  and  while  some  are,  as  before- 
mentioned,  only  smooth  valves  of  A.  splendeiis,  there  are  others 
which,  so  far  as  I  know,  cannot  be  identified  with  any  special 
form  of  that  species,  and  which  may  probably  be  themselves 
entitled  to  specific  rank.  A.  vulgaris  also,  as  generally  under- 
stood, includes  forms  which  have  really  no  close  relationship. 
One  such  form  is  nothing  but  A.  undulatus^  as  it  is  found  in 
Redondo  Beach  and  other  deposits,  with  mostly  fourteen  areas. 
The  deposit  mentioned  contains  numerous  valves  of  the  ordinary 
form,  with  six  areas,  a  few  with  eight,  ten  and  twelve,  a  good 
many  with  fourteen  and  a  few  with  sixteen  and  eighteen.  The 
structure  of  these  is  absolutely  identical  with  that  of  the  six- 
rayed  forms,  and  it  is  as  absurd  to  separate  them  as  it  would  be 
to  separate  forms  of  A.  Heliojjelta  with  six  areas  from  those  with 
more.  Other  forms  commonly  ranked  under  A.  vulgaris  are 
simply  valves  of  A.  adriaticus  with  the  pseudo-raphes  wanting, 
as  already  described,  while  others  seem  to  be  similar,  but  with 
deeper  and  more  abrupt  undulations.  The  undulations  in 
A.  adriaticus  are  very  shallow,  so  much  so  that  Grunow  origin- 
ally described  it  as  flat ;  but  in  view  of  the  considerable  variation 
in  this  respect  found  in  the  valves  of  A.  undulatus  and  other 
species,  the  character  would  seem  to  be  of  doubtful  importance. 

Probably  the  nearest  approach  to  a  really  flat  condition  is 
found  in  the  three-sided  A.  mari/landicus,  in  which  the  six  areas 
show  a  very  slight  difference  of  level  near  the  centre  only,  else- 
where blending  with  each  other  imperceptibly.  This  species  has 
a  more  or  less  distinctly  three-sided  umbilicus,  and  appears  to  be 
identical  with  the  Symbolophora  trinitatis  of  Ehrenberg.  Ralfs 
has  argued  against  this  view  on  the  ground  that  >S'.  trinitatis  is 


W.    M.    BALE    ON    SOME    OF   THE    DISCOID    DIATOMS.  43 

circular,  while  A.  marylandicus  is  three-sided,  but  in  Atlantic 
City  slides  valves  of  the  latter  species  are  found  in  which  the 
divergence  from  the  perfectly  circular  form  is  scarcely  perceptible, 
so  the  objection  falls  to  the  ground. 

It  is  sometimes  stated  as  a  character  of  the  genus  that  the 
depressions  of  one  valve  correspond  to  the  elevations  of  the  other, 
so  that  the  frustule  is  radially  undulated  as  a  whole.  That  this 
is  not  alwavs  the  case  is  evident  from  the  fact  that  the  two  valves 
have  often  a  different  number  of  areas.  But  I  find  on  comparing 
a  number  of  species  that  there  is  considerable  variation  in  regard 
to  the  undulations.  First  we  have  forms  in  which  the  undula- 
tions extend  to  and  include  the  rim  itself,  so  that  one  valve 
necessarily  fits  into  the  other.  A  striking  example  is  A.  trilingu- 
latics,  in  which  the  whole  valve  is  so  strongly  undulated  that  only 
three  points  of  the  margin  can  be  seen  at  any  one  focus.  Then 
we  have  such  species  as  A.  undulatus  and  A.  Heliojwlta,  in  which 
the  undulations  do  not  extend  outward  to  the  margin.  Apart 
from  the  border  itself,  the  sub-marginal  zone  is  about  on  a  level 
throughout,  but  the  one  set  of  areas  is  inflated  as  much  above 
that  level  as  the  other  is  below  it.  The  border  itself  slopes  down 
rather  steeply,  but  the  depressed  areas  often  reach  as  low  a  level 
as  the  extreme  margin.  Still,  the  width  of  the  hoop  ensures  that 
such  valves  may  be  placed  with  the  depressions  opposite  each 
other  without  coming  into  contact.  Lastly,  in  A.  splendens  the 
depressions  do  not  reach  as  low  as  the  margin,  while  the  eleva- 
tions rise  considerably  above  it  ;  even  with  a  narrow  hoop, 
therefore,  there  is  no  question  of  the  depressed  areas  of  opposite 
valves  clashing. 

According  to  the  definitions  of  Ralfs  and  Yan  Heurck,  a 
character  of  the  genus  is  the  division  of  the  valve  into  equal 
cuneate  segments,  which  would  exclude  from  it  the  A.  hispidus 
Grunow  (Van  Heurck,  Synopsis,  PI.  123,  fig.  2),  a  species  which 
is  described  as  having  narrow  elevated  compartments  alternating 
with  wide  depressed  ones.  I  believe,  however,  that  the  so-called 
elevated  compartments  of  A.  hisjndus  are  not  compartments  at 
all  in  the  same  sense  as  those  of  Actinoptychiis ;  neither  are  they 
elevations,  but  only  appear  so  owing  to  having  depressions  on 
each  side  of  them.  The  valve  is  a  shallow  cone,  by  far  the 
greater  part  of  which  is  occupied  by  about  eight  or  nine  broad 
radial  cuneate  areas,  all  of  which  are  depressions.  The  linear 
rays  or  ridges  are  simply  parts  of  the  surface  not  included  in  the 
depressions,  but  dividing  them.     These  rays  slope  down  evenly 


44  W.    M.    BALE    ON    SOME    OF    THE    DISCOID    DIATOMS. 

from  the  umbilicus  and  join  the  sub-marginal  zone  without  any 
interruption  of  the  structure,  which  indeed  is  similar  all  over  the 
valve,  except  the  narrow  hyaline  border.  The  valve  is  very  thin, 
covered  with  very  delicate  striae,  crossing  each  other  obliquely, 
and  most  easily  seen  on  the  narrow  rays.  The  secondary 
markings  consist  of  a  fine,  delicate,  irregular  reticulation,  at  the 
angles  of  which  are  dark  points  or  apiculi,  which  are  larger  and 
darker  on  the  narrow  rays  and  sometimes  round  the  inner  border. 
On  each  of  the  linear  rays,  near  the  border,  is  a  minute  process. 
In  Grunow's  figure  both  the  cuneate  areas  and  the  dividing  rays 
are  abruptly  truncate  at  the  border,  but  my  specimens  do  not 
agree  with  this,  as  the  narrow  rays  widen  out  in  a  regular  curve 
towards  the  border  zone,  with  which  they  are  continuous,  the 
cuneate  areas  having  of  course  their  outer  corners  rounded  off 
correspondingly,  while  they  do  not  quite  reach  the  border.  Owing 
to  the  thinness  of  the  valve,  however,  and  the  depressions  being 
by  no  means  abrupt  at  the  outer  ends,  this  character  might  often 
pass  unnoticed,  unless  the  valve  happens  to  be  lying  obliquely, 
when  it  becomes  more  conspicuous.  Possibly  my  specimens,  which 
were  found  in  recent  gatherings  from  Port  Phillip,  may  differ 
specifically  from  Grunow's  guano  specimens,  but  the  late 
Mr.  Comber  considered  them  the  same. 

I  think  the  characters  by  which  this  species  is  distinguished 
from  all  others  of  the  genus  are  such  as  to  entitle  it  to  at  least 
the  rank  of  a  sub-genus,  for  which  I  would  suggest  the  name 
Radiodiscus.  It  is  possible,  however,  that  it  may  be  brought 
under  the  genus  Actinodictyon  Pantocsek,  but  I  am  uncertain 
of  the  affinities  of  that  genus,  of  which  I  have  seen  no  specimens. 

I  have  a  single  valve,  apparently  belonging  to  A.  hispidus, 
which  differs  in  several  respects  from  the  usual  form.  Its 
depressions  are  extremely  slight,  there  are  no  secondary  markings 
and  no  apiculi,  and  the  cuneate  areas  terminate  in  a  hyaline 
band,  as  in  A.  splendens,  etc.;  it  also  has  exceedingly  narrow 
lines  (pseudo-raphes)  on  the  narrow  areas  ;  the  border  is  wanting. 
It  may  be  a  varietal  form,  or  possibly  an  internal  disc,  but  its 
pseudo-raphes  and  hyaline  bands  seem  to  indicate  a  closer  affinity 
with  such  forms  as  A.  adriaticus  than  would  be  inferred  from  the 
typical  form. 


Journ.  Quckett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  72,  April  1913. 


45 


SOME    NOTES    ON    BRITISH    FRESHWATER    RHAB- 
DOCOELIDA— A   GROUP    OF  TURBELLARIA. 

By  Henry  Whitehead,  B.Sc. 

(Read  January  28th,  1913.) 

Plate  4. 

The  members  of  the  group  Rhabdocoelida  are  very  similar  as 
regards  appearance,  shape  and  movements  to  the  Infusoria, 
though  they  are  generally  much  larger  and  their  complicated 
internal  structure  enables  them  to  be  distinguished  at  a  glance. 
The  Rhabdocoelida  form  a  branch  of  the  group  Turbellaria, 
to  which  the  larger  Planarians  found  in  fresh  water  also  belong. 
The  Turbellaria,  in  turn,  together  with  the  Liver-flukes  and 
Tape-worms,  are  included  in  the  phylum  Platyhelminthia 
or  Flat-worms. 

The  British  marine  Turbellaria  have  been  monographed  by 
Prof.  Gamble  (12),  and  our  President  has  taken  an  active  part  in 
the  study  of  the  land  Planarians  of  Australasia.  The  freshwater 
Turbellaria  have  apparently  received  but  little  attention  in  this 
country,  though  Prof.  Gamble  publishes  a  list  of  British  species 
in  the  Cambridge  Natural  History  (14). 

As  the  larger  freshwater  Planaria  (Tricladida)  cannot  be 
regarded  as  microscopic  objects,  and  are  therefore  of  no  special 
interest  to  the  Club,  the  writer  proposes,  in  this  paper,  to  deal 
only  with  the  group  Rhabdocoelida. 

Yon  Graff  has  written  two  monographs  on  this  group,  and  has 
devoted  much  time  to  valuable  work  on  anatomical  features ; 
and  it  is  chiefly  from  these  sources  that  the  information  con- 
tained in  this  paper  has  been  derived. 

The  writer  does  not  propose  dealing  in  detail  with  the 
anatomy,  but  rather  to  deal  with  the  Rhabdocoels  from  a  general 
point  of  view,  emphasising  matters  of  particular  interest  to  the 
field  naturalist. 

The  freshwater  Rhabdocoels  vary  in  size  from  1/2 5th  to  half 


46      H.    WHITEHEAD    ON    BRITISH    FRESHWATER    RHABDOCOELIDA 

an  inch  in  length.  They  are  generally  found  in  ponds,  lakes 
and  ditches,  and  less  frequently  in  running  water.  Like  many 
other  microscopic  inhabitants  of  ponds,  they  appear  in  great 
abundance  at  certain  seasons  of  the  year  and  then  suddenly 
disappear. 

The  body  is  more  or  less  transparent,  slightly  flattened,  and  is 
provided  with  cilia.  The  Turbellaria  are  remarkable  for  peculiar 
secretions  given  off  from  the  epidermis.  These  secretions  are  of 
two  distinct  kinds — one  a  mucous  fluid,  and  the  other  con- 
sisting of  very  small  solid  bodies,  or  rhabdites,  which,  on  coming 
in  contact  with  the  water,  produce  mucus.  Several  forms  of 
rhabdites  have  been  described  (spindle-shaped,  rod-shaped,  egg- 
shaped  and  spherical).  They  are  formed  in  special  glandular 
cells  which  lie  beneath  the  epidermis,  and  the  rhabdites  pass  to 
the  surface  by  means  of  minute  ducts. 

Another  interesting  feature  is  the  presence,  in  certain  species, 
of  nematocysts  similar  to  those  found  in  Hydra.* 

The  Rhabdocoels  are  provided  with  a  mouth,  a  pharynx  and 
an  unbranched,  sac-like  gut.  The  position  of  the  mouth  varies 
and  affords  a  valuable  generic  character.  It  may  lie  at  the 
extreme  anterior  or  in  a  median  position  anywhere  along  the 
ventral  surface  as  far  down  as  two-thirds  of  the  body  length. 

The  excretory  system  consists  of  renal  organs  which  are,  in 
some  cases,  somewhat  complicated  in  structure. 

The  nervous  system  is  simply,  and  comprises  a  two-lobed  brain 
and  a  pair  of  nerves  running  along  the  body  close  to  the  ventral 
surface.  In  some  species  the  pigmented  eyes  are  clearly  defined, 
in  others  the  eye  pigment  is  scattered,  and  in  some  cases  eyes 
are  absent. 

Some  of  the  freshwater  Rhabdocoels  have  at  their  anterior 
end  pit-like  depressions  which  contain  cilia  (PI.  4,  fig.  3,  cp). 
The  ciliated  pits  rest  upon  a  group  of  ganglion  cells  which  are 
connected  with  the  brain.  Similar  structures  are  found  in 
Nemertine  worms,  and  some  zoologists  consider  that  this 
suggests  affinity  between  the  groups.  Another  interesting  organ 
is  the  statocyst,  which  is  present  in  some  species.  This  consists 
of   a   cavity   containing    fluid,    in    which   is    suspended  a  highly 

*  Mr.  Scourfield  has  recently  called  my  attention  to  a  paper  by  C.  H. 
Martin  (20)  on  this  subject.  The  author  shows  conclusively  that  the 
nematocysts  are  derived  from  the  prey  upon  which  the  Turbellarian  feeds. 


A    GROUP    OF    TURBELLARIA.  47 

refractive  particle  of  calcium  carbonate — the  otolith  (or  statolith). 
The  statocysts  serve  as  organs  of  equilibration. 

Reproduction  is,  in  most  cases,  sexual.  The  animals  are 
hermaphrodite,  but  the  male  organs  ripen  first.  The  sexual 
organs  are  very  complicated,  and  the  details  of  their  structure 
are  of  great  value  in  classification.  On  this  account  it  is  often 
impossible  to  determine  the  species  of  immature  individuals,  and 
sometimes  it  is  necessary  to  have  specimens  in  both  the  male  and 
the  female  stages  before  identification  can  be  certain.  Fresh- 
water Turbellaria  undergo  no  metamorphosis,  and  newly  hatched 
individuals  are  similar  to  their  parents  in  general  appearance. 

Asexual  reproduction  occurs  only  in  the  section  Hysterophora. 
A  chain  of  individuals  is  formed  by  the  development  of  mouths, 
eyes,  etc.,  at  intervals  along  the  body.  Constriction  of  the  body 
and  gut  then  follow,  and  fresh  individuals  are  produced  by 
fission.  The  process  is  illustrated  in  PI.  4,  fig.  3.  Some  species 
which  reproduce  asexually  throughout  the  year  develop  sexual 
organs  in  the  autumn.  These  produce  eggs  which  lie  dormant 
through  the  winter. 

Considerable  interest  has  recently  been  aroused  in  certain 
green  or  yellow  cells  which  are  found  in  the  bodies  of  some 
species  of  Turbellaria.  The  green  cells  contain  chlorophyll  and 
are  able  to  decompose  carbon  dioxide  in  the  presence  of  sunlight. 
Two  marine  species,  Convoluta  roscoffiensis  and  G.  jmradoxa, 
found  on  the  coast  of  Brittany,  have  been  the  subjects  of  detailed 
study,  and  the  results  have  been  summarised  by  Prof.  Keeble  in 
a  little  book  entitled  Plant- Animals.  The  genus  Convoluta 
belongs  to  a  group  of  Turbellaria,  the  members  of  which  have 
not,  up  to  the  present,  been  found  in  fresh  water.  The  green  cells 
or  zoochlorellae,  as  they  are  termed,  are  now  regarded  as  algae 
similar  to  Chlamydomonas.  In  the  case  of  Convoluta  it  is 
certain  that  the  presence  of  zoochlorellae  is  of  benefit  to  the 
Turbellarian,  and  that  the  relationship  is  a  true  symbiosis. 

Von  Graff  (17)  mentions  twenty-five  species  of  freshwater 
Rhabdocoels  in  which  green  cells  have  been  found.  The  fresh- 
water species  containing  zoochlorellae  have  not  been  well 
studied,  and  some  zoologists  doubt  whether  there  is  mutual 
benefit  in  the  association.  This  aspect  of  the  subject  will, 
however,  be  dealt  with  later. 

The  Rhabdocoelida  live  under  various  conditions,  but  generally 


48       H.    WHITEHEAD    ON    BRITISH    FRESHWATER    RHABDOCOELIDA — 

prefer  still   or   gently  flowing    water   to   rapid   streams.       One 
species,  Prorhynchus  stag7ialis,  is  sometimes  found  on  moist  earth. 
Many  of   the   aquatic   forms    are   free   swimmers,  and  may  be 
captured  in  the  net  in  the  same  way  as  rotifers  and  water-fleas ; 
others  live  in  mud.     In  the  latter  case  it  is  best  to  pour  a  little 
of  the  mud  into  a  glass  tank    containing    clear  water,  and   to 
remove  any  Rhabdocoels  by  means  of  a  pipette.     They  should 
be  examined  in  a  live  box,  and    it  will  be  found  that  a  slight 
pressure    is    necessary    to    ensure    making    out    their   internal 
structure.     They  are  very  difficult  to  prepare  in  a  satisfactory 
manner  as  permanent  objects,  and  the  writer  has  made  numer- 
ous  experiments    with    a    view    to    narcotising    them,  but  with 
little  success.     Eucaine,  chloroform,  ether  and  alcohol  are  of  no 
use.     The  difficulty  seems  to  lie  in  the  fact  that  the  rhabdites 
are  discharged  as  soon  as  the  animal  is  irritated,  and  these,  of 
course,  produce  quantities  of  mucus.      Moreover,  the  epidermal 
cells  get  destroyed    during    the    process.     The  only  satisfactory 
method  of  killing  seems  to  be  by  means  of  some  hardening  re- 
agent, like  corrosive  sublimate  solution,  which  takes  effect  before 
the  mucus  and  rhabdites  can  be  discharged.     The  following  well- 
known  method  is  the  best.     The  specimen  is  placed  in  a  watch- 
glass  with  a  little  water,  the  bulk  of  which  is  withdrawn  by  a 
pipette.     A  drop  of  Lang's  Fluid  is  then  delivered  from  a  pipette 
on  the  side  of  the  watch-glass  and  is  allowed  to  run  over  the 
animal.     Death  is  almost  instantaneous,  and  but  little  shrinkage 
takes  place.     Even  with    this    method    the  writer  has  not   yet 
succeeded  in  killing   species    of    Mesostoma  without   disruption. 
After  remaining  in  Lang's  Fluid   from    ten  to  fifteen  minutes, 
the  specimens    are    removed   to    45-per-cent.   spirit.       They  are 
afterwards  passed  through  alcohol  of  increasing  strength,  stained 
with  borax-carmine  and  mounted  in  Canada  balsam  in  the  usual 
way. 

Some  of  the  Rhabdocoels  appear  to  be  entirely  vegetarian  in 
diet,  and  consume  desmids,  diatoms  and  unicellular  algae.  In 
fact,  care  is  sometimes  necessary  to  distinguish  the  food  from 
the  zoochlorellae.  The  latter,  however,  never  occur  in  the  gut. 
The  majority  of  species  take  animal  food,  which  consists  of  water- 
fleas,  small  worms,  etc. 

We  may  now  consider  a  few  typical  species  which  have  been 
taken  by  the  writer  in  the  neighbourhood  of  London. 


A    GROUP    OF   TURBELLARIA.  49 

Catenula  lemnae  (Ant.  Dug.). 

Occurs  in  ponds  and  lakes,  and  often  appears  suddenly  in 
considerable  numbers  in  collections  of  rain-water  during  the 
spring  and  summer,  and  disappears  as  rapidly  as  it  comes. 
It  is  white  and  thread-like  in  appearance,  consisting  of  a  chain 
of  2 — 4  individuals  (rarely  more)  and  attaining  a  length  of 
5  mm.  The  body  possesses  a  well-defined  head  lobe,  which  is 
marked  off  by  a  slight  constriction  and  a  ring  of  comparatively 
long  cilia  ;  a  statocyst  is  present.  The  usual  mode  of  repro- 
duction is  by  fission,  but  sexual  organs  are  developed  when  the 
pond  or  ditch  begins  to  dry  up. 

Microstomum  lineare  (Mull.)  (PI.  4,  fig.  3). 

This  species  is  very  similar  to  the  foregoing,  but  the  colour  is 
yellowish  or  greyish  brown.  It  is  usually  found  in  the  form  of 
a  chain  of  zooids  of  which  there  may  be  as  many  as  18.  The 
colony  attains  a  length  of  8  mm.  Each  zooid  develops  a  pair  of 
red  eyes,  behind  which  may  be  seen  the  ciliated  pits.  The  skin 
is  thickly  clad  with  cilia.  No  rhabdites  are  present,  but 
nematocysts,  similar  in  form  to  those  of  Hydra,  are  present  (20). 
The  figure  shows  the  manner  in  which  new  individuals  arise,  and 
various  stages  in  the  formation  of  mouths  may  be  seen.  The  gut 
is  common  to  all  the  zooids  in  the  chain,  until  fission  takes  place. 
The  writer  has  seen  desmicls  which  had  been  swallowed  for  food 
pass  along  the  common  gut  from  one  zooid  to  another.  Sexual 
organs  are  sometimes  produced,  and  the  ripe  eggs  are  oval  in 
shape  and  orange  or  dark  red  in  colour. 

This  species  is  fairly  common  in  stagnant  or  slowly  moving 
water.  It  has  been  found  in  thermal  springs  at  a  temperature 
of  130°  F.  and  also  in  brackish  water.  It  moves  slowly  on  a 
surface,  but  is  a  graceful  and  swift  swimmer. 

Dalyellia  viridis  (G.  Shaw)  (PI.  4,  figs.  1  and  2). 

Examples  of  this  species  attain  a  length  of  5  mm.,  and  are 
generally  spinach-green  in  colour.  The  colour  is  due  to  the 
presence  of  algal  cells  Which  lie  beneath  the  epidermis.  The 
body  is  truncated  in  front,  widens  towards  the  middle  and 
then  tapers  towards  the  tail.  There  are  two  bean-shaped  eyes. 
There  is  a  very  distinct  pharynx  and  the  gut  is  sac-like. 

Journ.  Q.  M.  C,  Series  II.— No.  72.  4 


50     H.  WHITEHEAD    ON    BRITISH    FRESHWATER    RHABDOCOELIDA 

Specimens  of  this  interesting  Rhabdocoel  were  taken  in  one  of 
the  ponds  in  Richmond  Park,  on  the  occasion  of  the  Club's  visit 
on  April  13th,  1912.  The  following  week  the  writer  took 
specimens  from  a  pond  near  Chigwell  Row,  Essex. 

It  was  noticed  that  the  animals  had  a  number  of  eggs  (in  one 
instance  49  were  counted)  in  the  spongy  body  tissue,  and 
individuals  in  this  condition  avoided  the  light.  As  far  as  could 
be  ascertained,  no  eggs  were  deposited  by  the  living  animals,  but, 
on  death,  the  eggs  were  liberated  on  the  decomposition  of  the 
body  of  the  parent.      So  far  none  of  these  eggs  have  hatched. 

Prof.   Sekera   (16)  of   Tabor,   Bohemia,   succeeded  in  keeping 

specimens  alive  for  some  time,  and  the  following  notes  are  taken 

from  the  account  of   his  observations.     Young   specimens  were 

taken  in  ponds  in  March,  when  ice   was   still    floating  on  the 

water.      The   animals   were   colourless,    but    as    soon    as    they 

approached    maturity,    and   the   sexual   pore    developed,   it    was 

noticed    that   a   few   algal  cells  (zoochlorellae)  had  entered  the 

body   cavity   by   this    means.     Streaks   of   green  granules  then 

began  to  spread  from  this  region  and  extend  beneath  the  cuticle 

over  the  whole    body,    until    finally   the   animal    became    quite 

green.     (T  would  remark,  in  parenthesis,  that  mature  specimens 

show    distinct   lines   or    bands  devoid    of    zoochlorellae.)       Solid 

food  in  the  form  of  diatoms,  rotifers,  etc.,  was  ingested  during 

this  period.     While  rapid  division  of  the  algal  cells  was  taking 

place,    they   formed   spherical  or  ellipsoid    clusters,  each    group 

being   surrounded   by  a  colourless  membrane.       The  membrane 

finally  disintegrated  and  the  algal  cells  were  dispersed  in  narrow 

irregular  lines  or   bands.     The   mature   zoochlorellae  showed  no 

signs   of   an  enveloping   membrane.      The  animals    exhibited   at 

this  period  a  distinct  tendency  to  crawl  towards  light  (phototactic), 

but  sank  to  the  bottom  of  the  vessel  at  night.     During  the  third 

week  eggs  were  formed  in  the  body  cavity.      The  worms  at  this 

stage  began  to  avoid  the  light  and  spent  the  whole  day  at  the 

bottom  of  the  vessel  or  under  vegetation.     During  the  first  week 

in  May  the  animals  died  off  rapidly,  and  with  the  decomposition 

of  the  body  the  eggs  were  liberated.      The  algal  cells  were  set 

free  and  continued  to  live,  and  developed  an  investing  membrane, 

then  passed  into  a  resting  stage,  probably  awaiting  an  opportunity 

of  invading  the  next  generation  of  Dalyellia. 

Prof.  Sekera  thinks  that  the  alga  is  of  little  or  no  value  to  the 


A    GROUP    OF    TURBELLAEIA.  51 

animal  in  the  way  of  providing  food,  his  reasons  being  that 
closely  allied  species,  living  under  similar  conditions,  do  not  con- 
tain algae,  and  that  solid  food  is  ingested  after  the  algal  cells  are 
fully  developed.  The  writer  hopes  to  investigate  this  question 
more  fully,  for  Sekera's  argument  does  not  seem  to  be  quite 
conclusive. 

Sir  J.  G.  Dalyell  (1)  wrote  an  account  of  this  interesting 
species  in  1814,  and  states  that  it  sometimes  occurs  in  large 
numbers,  and  then  suddenly  disappears.  He  found  his  specimens 
chiefly  in  the  spring,  but  some  were  found  in  the  autumn. 

Mesostoma  Spp.  (PL  4,  fig.  4). 

Some  of  the  species  of  Mesostoma  produce  two  kinds  of  eggs — 
thin-shelled  and  thick-shelled.  The  thick-shelled  eggs,  which 
contain  a  large  quantity  of  yolk,  are  produced  in  the  late  summer 
and  lie  dormant  during  the  winter.  The  young  hatched  from 
these  so-called  "  winter  "  eggs,  when  less  than  half  the  size  of  the 
parent  commence  to  produce  thin-shelled  eggs  with  but  little 
yolk.  It  is  probable  that  these  eggs  are  unfertilised ;  they  are 
produced  in  great  numbers  and  begin  to  hatch  in  April  and  May. 
The  young  hatched  from  these  eggs  attain  full  development 
and  produce  thick-shelled  "  winter "  eggs,  which  have  been 
fertilised  (14). 

There  is  some  difference  of  opinion  amongst  observers  as  to  the 
precise  nature  of  the  life-cycle  in  this  genus.  See  von  Graff  (17). 
They  vary  in  size  from  3  to  15  mm.  in  length  according  to 
the  species  and  condition.  They  live  in  clear,  still  or  slowly 
flowing  water  and  swim  or  creep  over  water-plants.  Their  food 
consists  of  entomostraca,  small  worms,  etc.,  which  are  sometimes 
caught  by  means  of  slime  threads. 

Bothromesostoma  personatum  (Schm.). 

Specimens  of  this  species  attain  a  length  of  about  7  mm.  and 
are  easily  identified  by  two  white  patches  which  look  like  large 
eyes  on  each  side  of  the  "head."  The  rest  of  the  body  is  either 
grey  or  black.  The  writer  has  taken  specimens  on  the  leaves  of 
water-lilies  and  creeping  on  the  surface  film,  at  Staines  and  at 
the  East  London  Waterworks.  The  genus  Bothromesostoma  is 
closely  allied  to  Mesostoma,  and  like  the  latter  produces  both 
summer  and  winter  eggs. 


52     H.   WHITEHEAD    ON    BRITISH    FRESHWATER    RHABDOCOELIDA 

Gyratrix  hermaphroditus  Ehrbg.  (PI.  4,  fig.  5). 

This  species  appears  to  be  widely  distributed.  It  is  about 
2  mm.  in  length,  is  almost  transparent  and  is  a  rapid  and 
graceful  swimmer.  It  can  easily  be  recognised  by  the  com- 
paratively long  stiletto  at  the  posterior  extremity.  This  weapon, 
although  connected  with  the  male  copulatory  apparatus,  is 
furnished  with  a  gland  which  probably  secretes  a  poison  of  some 
kind  and  is  used  by  the  animal  when  attacking  its  prey.  It  has 
a  well-marked  proboscis,  behind  which  are  two  eyes.  The  mouth 
and  pharynx  are  situated  near  the  middle.  As  a  general  rule, 
only  one  egg-capsule  is  present,  and  this  produces  one  or  two 
embryos. 

The  field  is  almost  unworked  as  regards  this  country.  Von 
Graff  records  110  species  of  Ehabdocoelida  from  Germany.  As  far 
as  the  writer  can  ascertain,  only  30  species  have  been  recorded 
from  the  British  Isles.  It  is  hoped  that  this  short  account 
mav  arouse  the  interest  of  some  of  the  members  of  the  Quekett 
Microscopical  Club  in  these  interesting  animals. 


List  of  British  Species. 

In  the  following  list  the  descriptions  of  the  species  will,  unless 
otherwise  stated,  be  found  in  Die  Silsswasserfauna  Deutschlands, 
Heft.  19.  The  initials  H.  W.  after  the  localities  denote  that  the 
species  has  been  found  by  the  author  at  those  places  : 

Sub-order  RHABDOCOELA. 

Section  Hysterophora. 

Fam.  CATENULIDAE. 

Catemila  lemnae  Ant.  Dug. 
Near  Cork  (14). 

Stenostomum  leucops  (Ant.  Dug.). 

Common  (14) ;  Clare  Is.  (24) ;  Staines  (H.  W.). 

S.  unicolor  0.  Schm. 
Clare  Is.  (24). 


Journ.   Q.M.C. 


Ser.  2,  Vol.  XII.,  PI.  4, 


rw 


H  W  del. 


Rhabdocoelida. 


A    GROUP    OF    TURBELLARIA.  53 

Fam.  microstomidae. 

Microstomum  lineare  (Miill). 

Fresh  water  (14)  :    Chigwell :   Higham's  Park,  (H.  W.)  ; 
"  In  all  Scottish  lochs  "  (19) ;  near  Dublin  (21). 

Macrostomum  appendiculatum  (0.  Fabr.)  (=  hystrix, 
Oe). 
Stagnant  water  (14) ;  Clare  Is.  (salt  water)  (24). 

Fam.  PRORHYNCHIDAE. 

Prorhynehus  stagnalis  M.  Schultze. 

In    Devonshire    rivers  (14) ;    L.    Lomond  (19)  ;     Fenton 
Tower,   E.   Scotland  (9). 

P.  curvistylus  M.  Braun. 
Near  L.  Lomond  (19). 

Section  Lecithophora. 

Fam.  DALYELLIIDAE. 

Dalyellia  diadema  Hofsten  (18). 

Chigwell  Row  (H.  W.).     This  species  appears  to  have  been 
recorded  only  once  before,  viz.  in  the  Bernese  Alps. 

D.  viridis  (G.  Shaw)  (=  heUuo  Miill). 

Generally    distributed  (14) ;     Richmond    Park,     Chigwell 
Row  (H.  W.) ;  Edinburgh  (9). 

D.  armigera  (O.  Schm.). 
Millport  (14). 

D.  Schmidtii  (L.  Graff). 
Millport  (14). 

D.  millportianus  (L.  Graff)  (9). 
Millport  (9). 

Jensenia  agilis  Fuhrm  (=  serotina,  Dorner). 
Richmond  Park,  Epping  Forest  (H.  W.). 

J.  truncata  (Abildg.). 

Abundant  in  fresh  water  (14),  L.  Lomond  (19). 

Phaenocora  (=  Derostomum)  punctatum  Orst. 
Theydon  Bois  (H.  W.)  ;  Edinburgh  (9). 

Opistomum  Schultzeanum  Dies. 
L.  Lomond  (19). 


54     H.   WHITEHEAD    ON    BRITISH    FRESHWATER    RHABDOCOELIDA 

Fam.  typhloplanidae. 

Rhynchomesostoma  rostratum  (Miill). 

Widely  distributed  (14) ;  Millport,  Edinburgh  (9). 

Typhloplana  viridata  (Abildg.)  (  =  Mesostoma  viridatum 
M.  Sch.). 
Manchester  (14) :  Clare  Is.  (24). 

Mesostoma  productum  (0.  Schm.). 
Cambridge  (14). 

M.  lingua  (Abbild.). 
Cambridge  (14). 

M.  Ehrenbergii  (Focke). 

Cambridge  (14). 

M.  tetragonum  0.  F.  M. 

Cambridge  (14). 

M.  Robertsonii  L.  Graff.  (9). 
Millport  (9). 

M.  flavidum  L.  Graff.  (9). 
Millport  (9). 

Bothromesostoma  personatum.  (0.  Schm.). 

Preston  (14)  ;  Staines,  E.   Lon.  Waterworks  (H.  W.). 

Fam.  POLYCYSTIDIDAE. 

Polycystis  Goettei  Bresslau. 

Nr.  Abergavenny,  L.  Lomond  (19). 

Fam.  GYRATRICIDAE. 

Gyratrix  hermaphroditus  Ehrbg. 

Common  in  fresh  water  (14)  ;  Chigwell  Row  (H.  W.) ;. 
St.  Andrews  (salt  water)  (9)  ;  Clare  Is.  (salt 
water)  (24). 

Sub-order  ALLOEOCOELA. 

Fam.  OTOPLANIDAE. 

Otomesostoma  auditivum  (Pless.)  (  =  Monotus  morgiensis 
et  relictus  Du  Plessis). 
Deep  waters  of  Scottish  lochs  (19). 


A    GROUP    OF    TURBELLARIA.  55 

Fam.  BOTHRIOPLANIDAE. 

Bothrioplana  sp.  ? 
Manchester  (14). 

Euporobothria  bohemica  (Vejd.). 
Tarbet,  L.  Lomond  (19). 

Bibliography. 
Confined  to  the  more  important  works  or  to  papers  quoted. 

1.  1814.    Dalyell,  J.  G.     Observations  on  Planariae. 

2.  1848.    Schmidt,  E.  0.     Die  Rhabdocoelen  (Strudelwiirmer) 

des  Siissenwassers. 

3.  1853.    Dalyell,  J.  G.     The  Powers  of  the  Creator,  vol.  ii. 

4.  1865.    Johnston,  G.     A  Catalogue  of  the  British  Non-para- 

sitical Worms  in  the  British  Museum. 

5.  1867.   Lankester,    E.    R.      Planariae   of    our    Ponds   and 

Streams.     Pop.  Sci.  Rev.,  vi.,  pp.  388-400. 

6.  1868.    Houghton,    W.      Our    Freshwater    Planariae.       In- 

tellectual Observer,  xii.,  pp.  445-449. 

7.  1878.    Jensen,  O..S.     Turbellaria  ad  litora  Norvegiae. 

8.  1879.    Hallez,  P.     Contiibutions  a  l'histoire   naturelle  des 

Turbellaries. 

9.  1882.    Graff,  L.  von.     Monographie    der  Turbellarien.    I. 

Rhabdocoeliden. 

10.  1885.    Braun,  M.     Die   Rhabdocoeliden   Turbellarien    Liv- 

lands. 

11.  1885.    Graff,  L.  von.     Article  "  Planarians  "  in  Encyc.  Brit. 

Ninth  Edition. 

12.  1893.    Gamble,  F.  W.     Contributions  to  a  knowledge  of  the 

British  Marine  Turbellaria.      Quart.  Journ.  Micro. 
Science,  vol.  xxxiv.,  p.  433. 

13.  1894.    Fuhrmann.     Der   Turbellarien   der    Umgebung    von 

Basel.     Revue  Suisse  de  Zoologie. 

14.  1901.    Gamble,  F.   W.     Flatworms    and    Mesozoa   in   Cam- 

bridge Nat.   Hist.,  vol.  ii. 

15.  1901.    Benham,    W.  B.     Lankester's   Treatise    on    Zoology. 

Pt.  IV.  Platyhelmia. 

16.  1903.    Sekera,  E.      Einige    Beitrage  zur    Lebensweise    von 

Vortex  helluo.  Zool.  Anz.,  xxvi.,  pp.  703-710. 


56      H.    WHITEHEAD    ON    BRITISH    FRESHWATER    RHABDOCOELIDA. 

17.  1904-8.    Graff,   L.    vox.     Das  Thierreich,    Turbellaria.    I. 

Acoela  und  Bhabdocoelida. 

18.  1907.    Hofsten,  Nils  von.     Studien  iiber  Turbellarien  aus 

dem  Berner  Oberland.     Zeitschr.  f.  wiss.  Zoologie, 
lxxxv.,  pp.  391-654. 

19.  1908.    Martin,  C.  H.     Notes  on  some  Turbellaria  from  the 

Scottish  Lochs.     Proc.  Roy.  Soc.  Edin.,  vol.  xxviii., 
pp.  28-34. 

20.  1908.    Ibid.      The    Nematocysts    of     Turbellaria.       Quart. 

Journ.  Micro.  Sci.,  vol.  lii.,  pp.  261-277. 

21.  1908.    Southern,  R.     Handbook  to  City  of  Dublin.     Brit. 

Assoc. 

22.  1909.    Graff,  L.  von.     Die  Siisswasserfauna  Deutschlands. 

Heft.  19. 

23.  1911.    Ibid.     Acoela,  Bhabdocoela  und  Alloeocoela  des  ostens 

der  vereinigten  staaten   von   Amerika.      Zeitschr. 
wiss.  Zoologie,  xcix.,  pp.  1-108. 

24.  1912.    Southern,  R.     Clare  Island  Survey.     Pt.  56.  Platy- 

helmia.     Proc.  Roy.  Irish  Acad.,  xxxi. 

Description  of  Plate  4. 

Pig.  1.  Dalyellia  viridis,  entire,   x  15. 

2.  Chitinous  copulatory  organ  of  D.  viridis,  X  150. 

3.  Microstomum  lineare,  entire,  x  20. 

4.  Mesostoma  sp.,  entire  with  thin-shelled  eggs,  x  20. 

5.  Gyratrix  hermaphroditus,  entire,  X  45.  b  c,  bursa  copu- 
latrix  ;  c,  cocoon  ;  c p,  ciliated  pit ;  e,  egg  ;  g,  gut ; 
m,  mouth  ;  o  v,  ovary  ;  p,  poison-sac  ;  p  h,  pharynx  ; 
p  rf  proboscis  ;  s  t,  stiletto  ;  it  t,  uterus. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  72,  April  1913. 


57 


THE    ROTIFERA    OF     DEVILS     LAKE,    WITH     DESCRIP- 
TION  OF  A   NEW   BRACHIONUS. 

By    Charles    F.    Rousselet,    F.R.M.S. 

{Read  January  2%th,  1913,) 

Plates  5  and  6. 

Devils  Lake,  the  largest  body  of  water  in  North  Dakota,  U.S.A., 
is  approximately  30  miles  long  by  5|  miles  wide  at  its  broadest 
part,  and  of  very  irregular  shape.  It  receives  its  water  from 
a  territory  which  forms  an  inland  drainage  basin  extending 
northwards  as  far  as  the  Turtle  Mountains. 

From  the  records  it  appears  that  the  level  of  the  lake  has 
fallen  14  feet  since  1883  (when  it  stood  at  1,439  feet  above  sea- 
level)  and  16  feet  between  1830  and  1883,  making  a  total 
recession  of  30  feet  in  eighty  years  with  a  corresponding  shrink- 
age of  the  area  of  the  lake.  At  the  time  of  its  highest  level  the 
lake  had  an  overflow  outlet  at  its  eastern  end  into  Stump  Lake 
lying  further  east,  and  it  is  probable  that  this  high-water  level 
was  reached  many  times  in  past  centuries  through  periods  of 
scanty  rainfall  succeeded  by  periods  of  unusually  abundant  pre- 
cipitation. In  1910  the  level  of  the  water  stood  at  1,425  feet 
above  sea-level,  but  fluctuates  about  4  feet  between  very  dry 
and  wet  periods.  The  lake  has  had  no  outlet  for  a  long  period, 
and  as  the  result  of  evaporation  the  water  has  become  brackish, 
the  salinity  increasing  gradually  by  concentration,  until  at  the 
present  time  the  water  has  a  specific  gravity  of  1*0076  (the 
sp.  gr.  of  sea  water  being  1*027). 

Besides  common  salt  the  water  contains  appreciable  quantities 
of  sodium  sulphate  and  magnesium  sulphate,  carbonate  and 
bicarbonate,  so  that  it  is  alkaline  as  well  as  brackish,  and  this 
no  doubt  accounts  for  the  very  peculiar  and  remarkable  Rotif  erous 


58  C.    F.    ROUSSELET    ON    THE    ROTIFERA    OF    DEVILS    LAKE 

fauna  it  contains,  which  is  abundant  in  numbers  but  very  re- 
stricted in  species. 

Since  1910  a  Biological  station  has  been  established  on  the 
shores  of  the  lake  by  the  Legislative  Assembly  of  the  State  of 
North  Dakota,  under  the  control  of  the  Biological  Staff  of  the 
State  University. 

At  the  request  of  Prof.  R.  T.  Young  I  have  at  various  times 
examined  samples  of  plankton  collected  by  him  in  July  1910  and 
May  1912,  and  have  found  therein  only  the  following  seven 
species  of  Rotifera,  the  majority  of  them  rare,  strange  and 
unusual  forms  : 

Triarthra   longiseta    Ehrenberg    (a    single    specimen,   possibly 

accidental). 
Pedalion fennicum  Levander.     {Very  abundant.) 
Asplanchna  Silvestrii  Daday.     (Very  abundant.) 
Brachionus  Midleri  Ehrenberg.     (Few.) 
Brachionus  satanicus  Rousselet.      (Very  abundant.) 
Brachionus  spatiosus  Rousselet.     (Very  abundant.) 
Brachionus  pterodinoides  sp.  nov.     (Few.) 

Two  of  these  forms  I  have  already  described  as  new,*  and 
have  now  to  introduce  a  third  still  stranger  species. 

The  single  specimen  of  Triarthra  may  have  been  introduced  by 
accident  in  one  of  the  tubes. 

Rotifera  are  essentially  freshwater  animals,  and  brackish  or 
salt  water  does  not  suit  the  great  majority  of  species;  this  ex- 
plains the  paucity  of  species  living  in  Devils  Lake. 

This  fact  does  not  militate  against  the  theory  of  cosmopolitan 
distribution  of  the  class,  on  the  contrary  it  confirms  it,  for 
Pedalion  fennicum  is  known  from  brackish  lakes  only  in  Finland, 
Egypt,  Central  Asia,  Asia  Minor,  etc.  The  presence  in  the  lake 
of  the  rare  Asplanchna  Silvestrii  suggests  that  the  "  Lago  di 
Villa  Rica,"  in  Chile,  from  which  it  was  first  obtained,  is  a 
brackish  lake.     Perhaps   Prof.  Silvestri,  who  obtained  Daday's 

*  Journ.  Q.M.C.,  Ser.  2,  Vol.  XL,  pp.  162  and  373  (April  1911  and  1912). 


WITH    DESCRIPTION    OF    A    NEW    BRACHIONUS.  59 

material,  would    be    good    enough    to    confirm    or    disprove    this 
suggestion. 

Brachionus  pterodinoides  sp.  nov.  (PI.  6,  fig.  1). 

This  new  Brachionus,  of  which  only  very  few  specimens  were 
found,  possesses  a  type  of  lorica  new  to  the  genus,  and  appears  to 
have  done  its  best  to  try  to  deceive  the  systematic  student  by 
making  itself  look  as  closely  as  possible  like  a  Pterodina.  For  quite 
a  considerable  time  I  was  unable  to  decide  whether  the  animal 
belonged  to  the  genus  Brachionus  or  Pterodina  until  I  found  one 
specimen  with  the  foot  and  its  two  small  toes  protruding,  which 
decided  the  question.  As  will  be  seen  on  referring  to  PI.  6,  fig.  1, 
the  lorica  is  nearly  circular  in  shape,  greatly  compressed  and 
flattened  dorso-ventrally,  and  possesses  a  foot-opening  situated 
just  below  the  middle  on  the  ventral  plate,  a  most  unusual 
situation  for  a  Brachionus,  but  usual  in  Pterodina.  The  dorsal 
plate  of  the  lorica  is  greatly  extended  posteriorly  beyond  the 
foot-opening,  and  under  this  projecting  cover  the  eggs  are  carried. 
The  lorica  is  smooth  except  anteriorly,  where  six  small  ridges 
mark  the  continuation  of  the  six  frontal  spines.  The  mental 
edge  is  a  nearly  straight  line  and  without  indentation.  As  far 
as  could  be  made  out  in  the  few  preserved  specimens  available, 
the  internal  anatomy  of  this  species  appears  to  be  normal.  In 
one  specimen  the  wrinkled  foot  was  extended,  showing  two  small 
pointed  toes,  as  shown  in  fig.  \c.  The  lateral  antennae  protrude 
high  up  above  the  middle  on  each  side. 

I  am  greatly  indebted  to  Mr.  F.  P.  Dixon-Nuttall  for  the 
three  figures  giving  an  excellent  idea  of  the  form  of  this  new 
species  and  new  type  amongst  the  Brachionidae. 

Size  of  lorica,  length  285 /x  (l/89th  inch),  width  224  fi  (1/1 14th 
inch). 

Brachionus  satanicus  Rousselet  (PI.  6,  fig.  2). 

When  describing  this  species  two  years  ago  *  I  had  specimens 
only  which  had  been  obtained  in  a  plankton  collection  made  in 

*  Journ.  Q.M.C.,  Ser.  2,  Vol.  XI.,  p.  162  (1911). 


60  C.    F.    ROUSSELET    ON    THE    ROTIFERA    OF    DEVILS    LAKE 

Devils  Lake  in  the  month  of  July  1910,  and  all  these  had  the 
shape  shown  in  the  figure,  with  two  long,  curved  and  widely- 
separated  posterior  spines.  Last  year  I  obtained  from  Prof.  Young 
a  collection  made  in  the  month  of  May  1912,  much  earlier  in  the 
season,  when  the  weather  in  North  Dakota  is  still  cold  and  the 
water  chilly.  Together  with  the  fully  developed  forms  in  this 
collection  I  found  a  much  smaller  form,  with  short  posterior 
spines,  curved  inwards  and  other  unusual  features  as  represented 
in  PI.  6,  fig.  26-/.  The  six  frontal  spines  and  the  mental  edge 
are  identical  with  those  of  the  larger  specimens,  but  the  shape  of 
the  body  and  the  form  and  size  of  the  posterior  spines  are  very 
different,  and,  strangest  of  all,  the  foot-opening  is  situated  on  the 
postero-dorsal  side  of  the  lorica,  a  quite  unheard-of  position  in 
this  genus.  My  first  impression  was  that  these  were  young 
animals  just  hatched  from  eggs,  but  this  is  evidently  not  so,  for 
some  specimens  were  seen  carrying  their  eggs  at  the  base  of  the 
foot  on  the  dorsal  side,  and  they  were  therefore  adults  reproducing 
freely.  I  can  only  conclude  that  this  represents  a  case  of 
dimorphism,  possibly  a  winter  form  which  gradually,  in  successive 
generations,  transforms  itself  into  the  larger  form  with  extended 
and  expanded  posterior  spines.  In  saying  this  I  do  not  mean 
that  the  smaller  forms  (PI.  6,  fig.  26-c)  can  themselves  grow  into 
the  form  of  fig.  2a,  but  that  their  offspring  will  in  a  few  genera- 
tions more  and  more  resemble  the  larger  form.  Intermediate 
forms  between  the  two  types  figured  were  not  seen.  In  order  to 
follow  up  this  transformation  it  will  be  necessary  to  obtain 
plankton  collections  made  about  twice  a  month  throughout  the 
year,  which  at  present  are  not  available.  It  certainly  is  not 
easy  to  see  how  the  dorsally  situated  foot-opening  can  change 
into  the  median  posterior  position  of  the  larger  form,  but  it  is 
known  that  in  the  case  of  some  Asplanchna  (A.  amphora, 
A.  Sieboldii)  the  transition  from  humped  into  saccate  forms  and 
other  changes  take  place  suddenly,  from  one  generation  to  the 
next,  produced  apparently  through  a  change  of  diet  and 
temperature,  as  shown   by  the   recent  researches   of  Dr.  Arno 


WITH    DESCRIPTION    OF    A    NEW    BRACHIONUS.  61 

Lange  *  and  Prof.  Powers. t  Should  these  changes  in  B.  satanicus 
be  confirmed,  it  will  be  the  first  record  of  true  dimorphism  in  the 
genus  Brachionus.  Fig.  2e  and  f  represent  variations  in  the 
shape  of  the  posterior  spines  of  the  smaller  form. 

Fig.  2a-f  were  drawn  from  my  own  preparations  by  Mr.  F.  R. 
Dixon-Nuttall,  to  whom  I  am  greatly  indebted  for  these  accurate 
and  beautiful  drawings. 

The  large  form  fig.  2a  measures  408  /x  (l/62nd  inch),  and 
the  small  form  250  /x  (1/1 00th  inch),  in  both  cases  including 
the  posterior  spines. 

Asplanchna  Silvestrii,  Daday. 
PI.  5,  figs.  1—9. 

This  fine  and  rare  species  was  first  described  by  Daday  in 
1902,J  and  found  by  him  in  plankton  collections  made  by 
Dr.  Silvestri  in  1899  in  the  Lago  di  Villa  Rica  in  Chile.  I  have 
not  been  able  to  ascertain  if  this  lake  is  brackish  or  not, 
Prof.  Daday  having  no  information  on  this  point,  but  the 
presence  therein  of  Pendalion  fennicum  seems  to  make  it  highly 
probable,  for  the  latter  species  has  never  yet  been  found  in 
fresh  water. 

In  the  collections  from  Devils  Lake  I  found  Asplanchna 
Silvestrii  in  great  abundance,  and  moreover  it  presented  a  marked 
dimorphism,  and  even  polymorphism,  for  all  gradations  from 
plain  saccate  forms  to  fully  developed  double-humped  animals 
were  represented  in  the  same  gathering.  PI.  5,  figs.  1 — 4 
represent  three  of  the  forms.  It  is  not  possible  for  me  to  say 
wThich  of  these  forms  appears  first,  or  which  is  hatched  from  the 
resting-egg,  and  what  causes  these  changes  of  form.  According 
to  the  observations  of  Prof.  J.  H.  Powers,  of  Nebraska  Univer- 

*  Zur  Kenntnis  von  Asplanchna  Sieboldii,  Zool.  Anz.  Bd.  38,  pp.  433-441, 
November  1911. 

f  A  case  of  Polymorphism  in  Asplanchna  simulating  mutation. 
American  Naturalist,  Vol.  XL VI.,  1912. 

\  Beitrage  zur  Kenntnis  der  Siisswasser  Mikrofauna  von  Chile.  Ter- 
meszetrajzi  Fiizeteh,  1902. 


62  C.    F.    ROUSSELET    ON    THE    ROTIFERA    OF    DEVILS    LAKE 

sity,  who  has  lately  published  an  account  of  similar  changes 
in  A.  amphora  found  by  him  in  a  brackish  pool,  it  is  caused  by  a 
change  of  diet,  from  vegetable  to  more  substantial  animal  food, 
and  even  cannibalistic  fare.  Prof.  Powers  found  that  the 
animals  hatched  from  resting-eggs  were  invariably  saccate,  and 
that  the  humped  and  larger  campanulate  forms  developed  from 
these. 

Asplanchna  Silvestrii  is  a  very  large  and  powerful  animal,  as 
is  shown  by  its  ability  to  capture,  swallow  and  digest  the 
large  and  vigorous  Diaptomus  which  abound  in  this  lake ;  one 
of  these  Copepods  was  seen  to  more  than  fill  its  stomach. 

The  male  was  also  found  ;  it  is  humped,  but  the  side  humps 
are  not  bind  as  in  the  humped  female,  as  shown  in  figs.  5 
and  6  ;  the  fertilised  resting-egg  is  represented  in  fig.  9.  The 
jaws  are  of  the  usual  type,  but  are  different  from  those  of  any 
other  species  of  the  genus,  as  is  shown  by  fig.  7.  The  rami 
are  massive,  and  have  a  semi-circular  cut-out  near  the  tip, 
which  is  peculiar ;  they  have  also  a  strong  basal  hook  and 
median  inner  tooth.  One  of  the  rami,  the  one  on  the  right 
side  when  the  basal  hooks  are  uppermost,  has  a  broad  flange 
near  its  apical  tooth  ;  this  serves  as  a  stop  for  the  opposite 
tooth  to  prevent  the  two  rami  overlapping  and  interlocking. 

The  prominent  lateral  humps  differ  markedly  from  those  of 
other  humped  species,  such  as  A.  Sieboldii  and  A.  amphora.  In 
A.  Silvestrii  these  are  bifid,  having  a  constriction,  more  or  less 
pronounced,  above  the  middle  of  the  hump,  giving  it  a  double 
rounded  outline  (fig.  1) ;  on  the  dorsal  side  there  is  a  pointed 
hump  near  the  middle  of  the  body  (fig.  2).  In  intermediate 
forms  the  humps  are  less  prominent  until  the  purely  saccate 
form  is  reached  (fig.  3),  which  in  shape  does  not  much 
differ  from  that  of  A.  Brightwelli.  Prof.  Powers  has  shown 
that  no  single  animal  goes  through  these  various  shapes  ;  they 
are  born  with  the  shape  they  possess  and  do  not  change  it  in 
their  lifetime,  but  their  jDrogeny  may  have  a  different  shape 
from  the  parent.     A  young  humped  individual  may  be  seen  in 


WITH    DESCRIPTION    OF    A    NEW    BRACHIONUS.  63 

the  uterus  of  a  saccate  female.  The  change  takes  place  more 
or  less  suddenly  from  one  generation  to  the  next.  The  general 
anatomy  of  A.  Silvestrii  follows  that  of  other  allied  species, 
and  but  few  points  need  be  mentioned.  The  two  gastric  glands 
are  large  and  kidney  shaped,  and  are  attached  to  the  long  and 
rather  wide  oesophagus.  The  stomach  has  the  usual  structure 
of  large,  dark-coloured  granulated  cells.  The  ovary  has  the 
form  of  a  narrow  horseshoe-shaped  band  with  a  single  row  of 
germ  cells.  An  enlarged  view  of  one  of  the  lateral  canals 
with  the  contractile  vesicle  is  given  in  fig.  8.  The  flame  cells 
are  closely  set  and  numerous,  numbering  over  thirty  ;  the  fine 
tube  to  which  they  are  attached  adheres  for  some  distance 
to  the  nerve-thread  of  the  ventro-lateral  antenna  on  each 
side. 

The  sense  organs  consist  of  three  pairs  of  antennae,  namely 
two  on  the  front  of  the  head,  two  dorso-lateral  and  two 
ventro-lateral  in  position,  each  ending  in  a  rocket-shaped  organ 
with  a  tuft  of  stiff  hairs  on  the  outside.  Two  finger-like, 
fleshy  processes  are  seen,  one  on  each  side  of  the  head  close 
to  the  corona.  Daday  mentions  that  the  animal  has  three  red 
eyes,  but  I  could  discover  only  a  single  small  cervical  red  eye, 
situated  on  the  small  brain. 

The  male  (figs.  5  and  6)  is  of  usual  structure,  and  has  two 
lateral  humps,  like  the  male  of  A.  amphora. 

Greatest  size  of  female  1,150  /x  (l/22nd  inch)  in  length  ;  male 
408  jx  (l/64th  inch)  ;  jaws  164  fx  (l/155th  inch)  ;  resting-egg 
195  /x  (1/1 20th  inch)  in  diameter. 

I  am  greatly  indebted  to  Mr.  Hammond  for  the  excellent 
figures  of  A.  Silvestrii  on  Plate  5. 

It  is  quite  possible  that  farther  plankton  collections,  and 
particularly  collections  made  amongst  the  aquatic  vegetation 
near  the  shores  and  in  the  bays  of  Devils  Lake,  may  reveal 
additional  species  of  Rotifera,  but  a  great  crowd  of  freshwater 
forms  cannot  be  expected  to  inhabit  this  brackish  and  alkaline 
lake. 


64  C.    F.    ROUSSELET    ON    THE    ROTIFERA    OF    DEVILS    LAKE. 

Explanation  of  Plates  5  and  6. 

Plate  5. 

Fig.  1.  Asplanchna  Silvestrii  Daday,  characteristic  female  with 

double  humps,  dorsal  view,  x  50. 

2.  A.  Silvestrii,  side  view,  x  50. 

3.  A.  Silvestrii,  saccate  form,  dorsal  view,  x  50. 

4.  A.  Silvestrii,  intermediate  form,  ventral  view,   x50. 

5.  A.  Silvestrii,  male,  side  view,  x  68. 

6.  A.  Silvestrii,  male,  dorsal  view,  x  68. 

7.  A.  Silvestrii,  the  jaws,  x217. 

8.  A.    Silvestrii,   vascular   system    with    contractile  vesicle, 

x  150. 
„    9.  A.  Silvestrii,  resting-egg,  x  65. 

Plate  6. 

Fig.   la.  Braehionus  pterodinoides  sp.  nov.,  dorsal  view,  x  196. 
,,     lb.    B.  pterodinoides,  ventral  view,  x  196. 
„     lc.    B.  pterodinoides,  side  view,   x  196. 
„     2a.  Braehionus  satanicus  Rousselet.     Normal  type,  x  180. 
„    2b.    B.  satanicus,  small  seasonal  form  (winter),  dorsal  view, 

X180. 
„     2c.    B.  satanicus,  small  seasonal  form  (winter),  ventral  view, 

Xl80. 
,,     2d.  B.  satanicus,  small  seasonal  form   (winter),    side  view, 

X  180. 
„    2e.    B.  satanicus,  small  seasonal  form  (winter),  variation  in 

posterior  spines,  x  200. 
,,     2f.    B.  satanicus,  small  seasonal  form  (winter),  variation  in 

posterior  spines,  x  200. 


Joum.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  72,  April  1913. 


Journ.Q.M.C. 


Ser.  2,Vol.Xir,Pl.  5. 


3 


^-Xr"-' 


1 


*   . 


9 


A. R. Hammond  del.et  lith..  West,>4ewma.n  imp. 

As  plan  elm  a  Silvestrii   Dadcuy. 


Journ.QM.C. 


Ser.  2,Vol.XII.Pl.  6. 


la 


/ 


lb. 


F.R. Dixon -Nuttall  del.adnat. 


A.R.Hammond    lith.. 
West,  Newman,  imp. 


Rotifera. 


65 


THE    PRESIDENT'S   ADDRESS. 

BY-PRODUCTS   OF   ORGANIC  EVOLUTION. 

By  Prof.  Arthur  Dendy,  D.Sc,  F.R.S. 

{Delivered  February  25th,  1913.) 

Plate  7. 

We   are   all   familiar   with   the   fact  that  in  the  manufacture 

of  any  particular  product  of  human  industry  the  raw  material 

employed  is  rarely  entirely  used  up,  a  more  or  less  considerable 

*• 

residue  generally  remaining  over  after  the  process  is  completed. 
In  so  far  as  the  prime  object  of  the  manufacturer  is  to  produce 
some  one  special  product,  the  residue  which  cannot  be  employed 
for  this  purpose  must  be  regarded  as  waste.  It  frequently 
happens  that  this  waste  product  is  a  highly  deleterious  substance, 
the  difficulty  in  the  disposal  of  which  may  constitute  a  very 
serious  obstacle  to  the  successful  prosecution  of  the  industry  in 
question.  On  the  other  hand,  it  also  frequently  happens  that 
what  were  primarily  waste  products  may  prove  to  have  a  value 
of  their  own  quite  apart  from  the  main  object  at  which  the 
manufacturer  is  aiming.  They  then  cease  to  be  merely  waste 
products  and  become  valuable  by-products,  perhaps  even  more 
valuable  than  the  main  product  itself. 

Thus  in  the  distillation  of  coal  in  a  gasworks  the  main  purpose, 
that  for  which  the  machinery  and  apparatus  are  primarily 
intended,  is  the  production  of  gas,  but  coke  and  tar  and  other 
by-products  are  also  produced,  all  of  which  are  now,  I  suppose, 
applied  to  some  useful  purpose,  and  thus  have  a  value  of  their 
own.  Indeed  the  existence  of  coal-tar  has  given  rise  to  a  whole 
series  of  new  industries,  involving  the  production  of  almost  endless 
substances,  such  as  the  wonderful  aniline  dyes  and  so  forth, 
which  many  people  will  regard  as  far  more  valuable  and  desirable 

Jourx.  Q.  M.  C,  Series  II. — No.  72.  5 


66  the  president's  address. 

objects  than  the  gas  for  the  sake  of  which  the  coal  was  originally- 
distilled. 

The   value   of  a  by-product   will  naturally  depend   upon   the 
particular   circumstances   of   the  case,   and   what  is   useless,  or 
even    harmful,  under   one   set  of   conditions  may  be  extremely 
valuable  under  another.     It  may  be  a  question  of  labour  supply 
or  of  transport,  or  it  may  be  that  the  discovery  of  some  new 
process  of  manufacture  in  a  totally  different  industry  suddenly 
creates  a  demand  for  a  by-product  that  was  previously  almost  or 
entirely  worthless.     It  is  perhaps  not  too  much  to  say  that  the 
success   or   failure   of  a  manufacturer  in   his  business  must  in 
many    cases    depend    upon    the   ingenuity    that    he    exhibits    in 
disposing  of  his  by-products ;  but  the  formation  of  such  products 
in  the  first  instance  cannot  be  avoided,  and  they  may  go  on  being 
produced,  and  constitute  a  characteristic  feature  of  the  industry 
for  a  long  time,  before  some  new  factor  in  the  circumstances  of 
the  case  may  give  them  a  special  value  of  their  own.     It  may 
well  be  that  this  may  never  happen  at  all,  and  the  substances 
in   question   may   simply  accumulate  in   harmless,  if   unsightly, 
heaps,  or,   on    the   other   hand,   they  may  become  so  offensive, 
or  even  dangerous,  as  to  render  impossible  the  continuance  of 
the  industry  which  gives  rise  to  them. 

In  short,  it  would  be  difficult  to  exaggerate  the  importance 
of  the  part  played  by  by-products  in  the  evolution  of  human 
industries.  Such  industries  are  necessarily  subjected  to  a  severe 
struggle  for  existence  in  ceaseless  competition  with  one  another, 
and  in  this  struggle  the  by-products  afford  abundant  opportunity 
for  the  elimination  of  the  least  fit  by  the  process  of  natural 
selection.  The  by-products,  however,  did  not  themselves  arise 
through  any  process  of  selection,  but  as  the  unintentional  and 
inevitable  results  of  those  chemical  and  physical  changes  which 
accompany  the  manufacture  of  the  main  product. 

We  may  thus  look  upon  a  human  industry  as  an  organism, 
which  undergoes  a  process  of  evolution  subject  to  the  control 
of  natural  selection,  and  some  of  the  most  characteristic  features 
of  which  are  to  be  found  in  its  by-products.  Indeed  it  may 
often  be  recognised  and  identified  by  its  by-products  almost  if 
not  quite  as  readily  as  by  the  product  for  the  sake  of  which 
it  primarily  exists. 

We  must  not,  of  course,  push  our  analogy  too  far,  but  I  hope  to 


THE    PRESIDENT'S    ADDRESS.  67 

be  able  to  convince  you  that  in  the  evolution  of  living  organisms 
themselves  by-products  have  played  a  part  not  unlike  that  which 
they  have  played  in  the  evolution  of  industries. 

You  have  probably  already  began  to  wonder  why  I  should 
have  chosen  such  a  subject  as  this  for  an  address  to  a  micro- 
scopical club  ;  but  the  reason  will  now  become  apparent,  for 
I  propose  to  endeavour  to  elaborate  the  ideas  which  I  have 
been  suggesting  to  you  by  reference  to  organisms  which  have 
long  been  favourite  subjects  with  the  microscopist,  and  to 
characters  which  can  only  be  investigated  with  the  aid  of  the 
microscope. 

We  shall  perhaps  find  nowhere  in  the  animal  kingdom  a  more 
exact  analogy  to  the  utilisation  of  waste  products  in  human 
industries  than  in  the  curious  rotifer  Melicerta  janus.  As 
you  are  all  aware,  this  minute  but  highly  complex  organism 
builds  for  itself  a  beautiful  dwelling-place  out  of  pellets  of  its 
own  dung.  I  do  not,  however,  propose  to  dwell  upon  such  cases 
as  this,  and  for  our  present  purposes  I  must  ask  you  to  allow 
me  to  interpret  the  term  waste  products,  or  if  you  prefer  it,  by- 
products— for  it  is  obvious  that  the  two  cannot  be  sharply 
distinguished  from  one  another — in  a  less  literal  manner. 

There  is,  in  my  opinion,  no  group  of  organisms  better  suited 
for  the  illustration  of  the  fundamental  principles  of  organic 
evolution  than  the  Sponges.  This  arises  from  the  fact  that  they 
combine  with  an  essential  simplicity  of  structure  an  inexhaustible 
variation  in  detail,  and  that  this  variation  is  to  a  very  great  extent 
clearly  and  precisely  expressed  in  the  form  of  the  microscopical 
calcareous  or  siliceous  spicules  of  which  the  skeleton  is  ordinarily 
composed.  Moreover,  it  appears  that  an  unusual  number  of 
connecting  links  have  been  preserved  to  the  present  day,  so  that 
we  are  able  to  trace  beautiful  evolutionary  series  in  the  wonderful 
spicule -forms  of  existing  species. 

Take,  for  example,  the  siliceous  spicules  which  are  so  character- 
istic of  the  Tetraxonida.  These  are  probably  all  to  be  derived 
from  a  primitive  ancestral  form  or  archetype  (fig.  1)  consisting 
of  four  rays  diverging  at  equal  angles  from  a  common  centre, 
like  the  axes  which  connect  the  angles  of  a  regular  tetrahedron 
with  its  central  point.  The  assumption  of  this  regular  geometri- 
cal form  by  a  non-crystalline  substance  like  the  hydrated  silica, 
or  opal,  of  which  these  spicules  really  consist,  is  a  very  remarkable 


68  the  president's  address. 

fact,  especially  when  we  consider  how  very  widely  it  is  afterwards 
departed  from  on  most  lines  of  spicule  evolution.  It  has  been 
suggested  that  the  equiradiate  and  equiangular  tetraxon  was 
originally  adapted  to  the  interstices  in  a  system  of  spherical 
flagellated  chambers  arranged  tetrahedrally.  This  seems  probable 
enough,  but  in  any  case  we  can  safely  take  this  form  as  our 
archetype  without  indulging  in  speculations  as  to  its  origin. 

If  we  now  imagine  one  ray  of  our  archetype  becoming  greatly 
elongated  we  get  a  common  form  of  "  triaene "  spicule  known 
as  the  "  plagiotriaene "  (fig.  2),  with  a  long  arm  or  "  shaft " 
and  three  short  arms  or  "cladi,"  but  still  with  all  the  angles 
equal.  If  we  imagine  the  angles  which  the  cladi  make  with 
the  shaft  to  be  increased,  so  that  the  cladi  come  to  point  forwards, 
we  get  the  "protriaene"  (figs.  5,  5a);  if  the  cladi  extend  at 
right  angles  to  the  shaft  we  get  the  "  orthotriaene  "  (fig.  3),  and 
if  they  point  backwards  we  have  the  "  anatriaene  "  or  grapnel 
spicule  (figs.  4,  4a). 

All  these  long-shafted  triaenes  are  typically  oriented  with 
the  cladi  at  or  near  the  surface  of  the  sponge,  and  the  shaft 
directed  centripetally  inwards,  so  that  the  entire  skeleton  acquires 
a  markedly  radiate  arrangement.  The  cladi  of  the  orthotriaenes 
usually  form  a  support  for  the  dermal  membrane  at  the  surface 
of  the  sponge,  beneath  which  they  are  spread  out  tangentially, 
and  their  efficiency  as  a  dermal  skeleton  may  be  greatly  increased 
by  their  bifurcation  ("  dichotriaenes,"  figs.  6,  Ga).  In  the  case  of 
the  protriaenes  and  anatriaenes  the  distal  portions  of  the  shafts, 
bearing  the  sharp-pointed  prongs  or  cladi,  usually  project  for 
some  distance  beyond  the  surface  of  the  sponge,  and  in  this 
position  they  probably  serve  either  to  ward  off  the  attacks  of 
enemies  or  to  entangle  minute  organisms  whose  decomposition 
may  supply  the  minute  organic  particles  upon  which  the  sponge 
depends  for  its  food  supply  and  which  will  be  carried  inwards 
by  the  inflowing  stream  of  water. 

A  still  more  remarkable  modification  is  met  with  in  the 
"  discotriaene,"  in  which  the  shaft  is  reduced  to  a  short  peg 
inserted  in  the  middle  of  a  flat  disk  formed  by  fusion  of  the 
cladi.  The  entire  spicule  then  assumes  somewhat  the  form  of 
a  carpet-nail.  In  the  genus  Discodermia  we  find  these  disco- 
triaenes  stuck  close  together  all  over  the  surface  of  the  sponge,, 
and  forming  an  impenetrable  mail-armour. 


THE    PRESIDENT'S    ADDRESS.  69 

In  Stelletta  vestigium,  on  the  other  hand,  the  cladi  are  reduced 
to  the  merest  vestiges,  and  some,  if  not  all  of  them,  may  com- 
pletely disappear,  while  the  shaft  remains  greatly  elongated 
and  forms  practically  the  entire  spicule  (figs,  la — Id).  Possibly 
the  simple  "  oxeote  "  spicules  of  this  and  allied  species  (fig.  8) 
have  arisen  in  this  manner. 

An  altogether  different  line  of  evolution  from  the  primitive 
tetraxon  archetype  appears  to  have  given  rise  to  the  typical 
oxeote  spicules  (figs.  9,  10)  of  the  monaxonellid  division  of  the 
Tetraxonida.  Here  two  of  the  four  rays  of  the  primitive 
tetraxon  have  probably  entirely  disappeared,  while  the  remaining 
two  have  become  extended  in  a  straight  line  with  one  another. 
In  the  typical  "  stylote "  (fig.  11)  and  "  tylostylote "  (fig.  12) 
spicules  probably  only  a  single  ray  persists,  so  that  the  so-called 
organic  centre  is  situated  at  one  end  instead  of  in  the  middle. 
In  many  species  the  oxea,  styles  or  tylostyles  become  ornamented 
with  sharp  spinose  excrescences  (fig.  13). 

In  most  of  the  cases  which  we  have  so  far  considered  it  is 
easy  to  see  that  we  are  dealing  with  adaptive  modifications. 
The  orthotriaene,  dichotriaene,  protriaene,  anatriaene  and 
discotriaene  are  all  obviously  well  suited  for  the  fulfilment  of 
their  specialised  and  differentiated  functions,  and  the  evolution 
of  these  forms  is  more  or  less  readily  explicable  in  accordance 
with  the  well-known  principle  of  the  natural  selection  of 
favourable  variations.  The  origin  of  the  linear  spicules  of  the 
monaxonellid  forms  by  complete  suppression  of  two  or  three  of 
the  rays  of  the  primitive  tetraxon  is,  perhaps,  not  so  easy  to 
account  for  as  is  that  of  the  triaene  series  from  the  same 
starting-point.  In  both  cases  the  determining  factor  was 
probably,  in  the  first  instance,  the  development  of  a  radially 
arranged  canal-system,  requiring  a  corresponding  radial  arrange- 
ment of  the  supporting  skeleton,  which  could  not  be  obtained 
wTith  spicules  of  the  primitive  tetraxon  form.  That  the  evolu- 
tion of  the  necessary  linear  spicules  has  taken  place  along 
different  paths  in  different  cases  is,  however,  nothing  to  be 
surprised  at ;  it  is  merely  one  of  those  instances  of  convergence 
which  are  quite  as  common  amongst  sponges  as  amongst  other 
groups  of  the  animal  kingdom. 

In  the  most  primitive  tetraxonid  sponges,  which  represent 
more    or    less    closely    the    ancestral    forms    from    which    both 


70  THE    PRESIDENT'S    ADDRESS. 

Tetractinellida  and  Monaxonellida  have  doubtless  been  derived, 
we  still  meet  with  some  of  the  earliest  stages  of  spicule 
evolution.  Take,  for  example,  Dercitopsis  ceylonica,  collected 
by  Prof.  Herdman  in  Ceylon,  and  described  in  my  report  on 
the  Ceylon  sponges.  Here  we  find  the  tetraxon  spicule  in  all  its 
primitive  simplicity  (fig.  25),  but  associated  with  it  we  get 
numerous  diact  spicules  (figs.  26a — 26c),  evidently  derived  from 
the  tetract  by  loss  of  two  of  the  original  rays,  and  clearly 
showing,  by  a  swelling  or  an  angulation  in  the  middle,  that 
two  rays  still  remain.  From  such  obvious  diactine  spicules  as 
these,  transitional  forms  lead  the  way  to  the  comparatively 
large,  straight  oxeote  spicules  which  occur  in  the  same  and  in 
many  other  sponges,  and  which  no  longer  show  any  trace  of 
their  tetraxon  and  tetract  ancestry. 

In  Dercitopsis  and  its  relations — i.e.  in  the  Homosclerophora 
— although  there  may  be  great  differences  as  regards  the  size 
of  the  various  spicules,  yet  we  cannot,  as  in  most  of  the  higher 
groups,  sort  these  spicules  out  into  two  distinct  categories  — 
megascleres  and  microscleres — for  innumerable  gradations  exist 
between  large  and  small. 

In  the  course  of  further  evolution,  however,  the  distinction 
between  megascleres,  or  skeleton  spicules,  and  microscleres,  or 
flesh  spicules,  becomes  very  strongly  marked.  Both  have 
doubtless  had  a  common  origin  in  the  ancestral  tetraxon 
archetype,  but  whereas  the  former  are  obviously  adapted  as  the 
principal  skeletal  elements,  and  are  arranged  accordingly  in 
the  sponge,  the  latter  are  usually  scattered  at  random  through 
the  soft  ground  substance  like  plums  in  a  pudding,  and  neither 
in  form  nor  arrangement  show  any  evident  adaptation  to  the 
requirements  of  the  organism. 

Indeed,  the  microscleres  are  usually  so  extremely  minute, 
requiring  high  powers  of  the  microscope  to  make  out  their 
true  form,  that  is  impossible  to  believe  that  their  presence  can 
exercise  any  important  influence  upon  the  well-being  of  the 
sponge.  Still  less  is  it  possible  to  believe  that  the  particular 
shape  which  they  may  assume,  which  is  often  highly  remarkable, 
can  be  of  any  consequence  to  their  possessor.  There  are,  of  course, 
exceptions  to  this,  as  to  every  generalisation,  and  sometimes  we 
find  microscleres  forming  a  dense  protective  external  crust,  as 
in  the  case  of  the  "  sterrasters  "  of  Geodia,  or  projecting  into  the 


THE    PRESIDENT'S    ADDRESS.  71 

inhalant  canals,  where  they  may  perhaps  serve  to  filter  the 
incoming  water  and  guard  against  parasites,  as  in  the  case  of 
the  "  sigmata  "  of  Esp>erella  murrayi ;  but  in  the  vast  majority 
of  cases  it  is  impossible  to  assign  any  value  at  all  to  the 
presence  of  microscleres.  Indeed,  the  numerous  species  of 
horny  sponges  seem  to  get  on  quite  as  well  without  these 
bodies. 

Nevertheless  we  find  that  the  microscleres,  when  present, 
are  characterised  by  very  definite  and  constant  forms,  and  many 
of  them  are  amongst  the  most  beautiful  and  wonderful  objects 
that  come  under  the  observation  of  the  microscopist.  So  constant 
and  characteristic  are  they  that  they  afford  by  far  the  most 
convenient  and  most  reliable  data  for  the  classification  of  the 
tetraxonid  sponges.  Particular  species,  and  even  particular 
genera  and  families  of  these  sponges,  are  characterised  by  the 
presence  of  highly  specialised  forms  of  microscleres,  and  in  the 
case  of  species  the  characteristic  form  is  almost  invariable. 

There  can  be  no  doubt  that  the  microscleres  have  undergone 
an  evolution  along  definite  lines,  and  one  species  of  a  genus  is 
commonly  distinguished  from  another  by  differences  in  the 
shape  of  these  spicules,  which,  though  constant,  appear  at  the 
same  time  to  be  utterly  trivial — as,  for  example,  the  difference 
in  the  shape  of  the  teeth  at  the  small  end  of  the  "  isochelae  "  in 
Cladorhiza  pentacrinus  (figs.  23,  23a)  and  Cladorhiza  (?)  tridentata 
(figs.  24,  24a).  There  may  be  several  kinds  of  microsclere  in 
the  sponge,  all  characteristic  of  the  species,  but  a  single  sponge 
may  contain  many  thousands,  or  perhaps  millions,  of  the  same 
kind,  all  exactly  alike  in  shape  and  size  except  for  an  occasional 
individual  variation  such  as  occurs  in  all  organisms. 

The  shape  of  the  microscleres  appears  to  be  quite  independent 
of  their  position  in  the  sponge,  and  must  obviously  be  attributed 
to  some  specific  peculiarity  of  the  ovum  from  which  the  sponge 
developed.  It  is  clearly  of  a  blastogenic  and  not  a  somatogenic 
character,  and  it  is  usually  much  more  remarkable  and  quite 
as  constant  as  that  of  the  megascleres  of  the  same  species. 

The  microscleres  of  the  tetraxonid  sponges  may  be  divided 
into  two  categories,  termed  astrose  and  sigmatose  respectively. 
The  former  (figs.  14a — 14A)  may  be  derived  from  the  tetraxon 
archetype  by  multiplication  of  the  rays — due  apparently  to 
meristic  variation — accompanied  usually  by  diminution  in  size  of 


72  the  president's  address. 

the  whqle  spicule  ;  at  the  same  time  the  rays  may  become  spiny 
or  branched  in  a  variety  of  ways,  or  even  soldered  together  to 
form  a  solid  siliceous  ball  (Geodia). 

The  sigmatose  microscleres  are  more  remarkable  and  more 
constant  in  form.  They  are  essentially  linear  spicules,  and 
appear  to  be  derived  from  minute  diactinal  oxea.  These  may  be 
straight  ("  microxea,"  fig.  15)  or  bow-shaped  ("  toxa,"  figs.  16,  18a, 
186),  or  their  extremities  may  become  bent  over  to  form  hooks 
("  sigmata,"  figs.  17a,  176,  19).  A  very  peculiar  modification  of 
the  sigmata  is  found  in  the  "  diancistra  "  (fig.  21),  which  often 
resemble  nothing  so  much  as  pocket-knives  with  the  blades  half 
open.  From  the  sigmata  have  also  doubtless  arisen  the  "  chelae,"  * 
characteristic  of  the  family  Desmacidonidae,  and,  in  my  opinion, 
the  most  wonderful  of  all  sponge  spicules.  Three  different  chelae 
are  shown  in  figs.  22 — 24a. 

A  typical  chela  consists  of  a  curved  shaft,  bearing  a  number, 
commonly  three,  of  recurved  teeth,  resembling  the  flukes  of  an 
anchor,  at  each  end.  The  flukes  are  sometimes  expanded  into 
thin  blades,  and  so  also  may  be  the  shaft.  Sometimes  the  flukes 
at  the  two  ends  of  the  spicule  are  equal  in  size  ("  isochelae," 
figs.  22,  22a),  sometimes  those  at  one  end  are  larger  than  those 
at  the  other  ("  anisochelae,"  figs.  23 — 24a),  while  in  the  genus 
Melonanchora  a  very  curious  effect  is  produced  by  the  meeting 
and  fusing  of  opposite  flukes  of  an  isochela  at  the  equator  of 
the  spicule.  Minute  differences  in  the  form  and  number  of  the 
flukes  and  the  shape  of  the  shaft  appear  to  be  constant,  at  any 
rate  within  the  limits  of  a  species  ;  indeed,  the  very  numerous 
species  of  Desmacidonidae  are  to  a  large  extent  distinguished  from 
one  another  by  these  characteristics  (compare  figs.  23,  23a,  and 
24,  24a). 

The  same  constancy  of  form  is  to  be  observed  in  the  sigmata, 
although  here  there  is  less  scope  for  specific  differences.  In 
both  cases  the  spicule,  instead  of  remaining  smooth,  may  become 
more  or  less  roughened  by  the  development  of  minute  projections. 
This  is  shown,  for  example,  in  the  sigmata  of  the  genus  Par- 
esperella  (fig.  20),  where  a  row  of  small  projections,  like  the  teeth 

*  It  is  perhaps  unnecessary  to  discuss  here  the  evidence  for  believing 
that  the  chelae  have  arisen  from  sigmata.  It  is  derived  partly  from  the 
development  of  the  chelae  themselves  and  partly  from  the  occurrence  of 
intermediate  forms. 


THE    PRESIDENT'S    ADDRESS.  73 

of  a  saw,  occurs  at  each  end  of  the  shaft,  just  where  it  bends 
round. 

Now  it  appears  to  me  quite  idle  to  argue  that  minute  differ- 
ences in  the  form  of  the  microscleres,  such  as  I  have  just  described, 
are  of  any  importance  to  the  sponge  in  whose  soft  tissues  these 
microscopic  spicules  are  scattered  without  order  or  arrangement. 
Nevertheless  they  constitute,  as  I  have  already  said,  constant 
specific  characters,  and  have  undoubtedly  arisen  by  some  process 
of  evolution,  one  form  Lading  to  another  just  as  in  the  case 
of  any  other  characters.  Such  characters  are,  of  course,  by  no 
means  confined  to  sponge  spicules  ;  they  may  be  more  or  less 
exactly  paralleled,  for  example,  in  the  frustules  of  Diatoms,  the 
shells  of  Foraminifera  and  Kadiolaria,  and  the  calcareous  spicules 
of  Holothurians.  Natural  selection  cannot  be  directly  respon- 
sible for  their  origin.  How,  then,  are  they  to  be  accounted 
for? 

Before  attempting  to  answer  this  question  let  us  inquire  how 
a  microsclere  actually  arises  in  the  sponge.  It  appears  that, 
from  an  early  stage  in  embryonic  development,  certain  cells, 
known  as  scleroblasts,  or  mother-cells,  are  set  aside  for  the 
purpose  of  spicule-formation.  These  mother-cells  have  the  power 
of  extracting  silica  in  solution  from  the  sea-water  which  circu- 
lates through  the  sponge,  and  depositing  it  in  the  form  of  solid 
opal,  and  in  the  particular  shape  characteristic  of  each  spicule. 
Each  separate  microsclere  arises  thus  in  the  interior  of  a  single 
mother-cell.  Let  us  examine  a  little  more  closely  the  conditions 
under  which  it  is  deposited. 

The  mother -cell  is,  of  course,  a  nucleated  mass  of  protoplasm, 
and  it  appears  to  be  bounded  on  the  outside' by  a  more  or  less 
definite  cell -membrane.  The  spicule,  at  any  rate  in  the  case 
of  sigmata  and  chelae,  appears  to  be  deposited  on  the  inner 
surface  of  this  membrane,  and  this  fact  probably  explains  why 
it  is  curved.  If  we  assume,  as  seems  probable,  that  the  mother- 
cell  continues  to  grow  while  the  spicule  is  being  deposited,  and 
that  the  spicule  is  adherent  to  the  cell-membrane,  then  we  may 
further  suppose  that  the  increasing  tension  and  expansion  of  the 
latter  may  cause  the  thin  siliceous  film  to  split  into  flukes  or 
teeth.  Probably,  then,  the  form  of  the  spicule  is  largely  due  to 
mechanical  causes.  We  cannot,  however,  explain  the  minute 
details  of  structure  so  simply  as  this,  for  why  should  the  chela 


74  the  president's  address. 

of  one  species  have  always  three  flukes  and  that  of  another 
always  more  ?  Why  should  the  two  ends  in  some  cases  be  equal 
and  in  others  unequal  1  Why  should  the  teeth  at  the  small  end 
sometimes  be  shaped  as  in  fig.  23  and  sometimes  as  in  fig.  24  ? 
and  why  should  some  be  roughened  with  spines  and  others  not  ? 
We  must,  I  think,  assume  that  these  minute  differences  are 
dependent  upon  minute  differences  in  the  constitution  of  the 
protoplasm  of  which  the  mother-cell  is  composed.  It  may  be 
a  question  of  the  chemical  and  physical  composition  of  the 
cytoplasm  in  which  the  spicule  is  actually  deposited,  or  it  may 
be  that  the  nucleus  exerts  some  direct  controlling  influence 
upon  the  form  of  the  spicule,  of  the  nature  of  which  we  know 
nothing. 

At  any  rate  we  can  hardly  be  wrong  in  attributing  specific 
differences  of  spicule-form  to  corresponding  differences  in  the 
constitution  of  the  mother-cells  by  which  they  are  secreted.  The 
remarkable  thing  is  that  such  differences  should  be  so  constant, 
not  only  throughout  hundreds  of  thousands  of  mother-cells  in 
the  same  sponge,  but  throughout  the  mother-cells  of  all  the 
individuals  of  the  same  species.  We  can  only  suppose,  as  I  said 
before,  that  this  constancy  depends  upon  some  constant  peculiarity 
of  the  germ-plasm  from  which  all  the  cells  of  the  individual  and 
all  the  individuals  of  the  species  originate.  Obviously  the  ferti- 
lised ovum  must  contain  within  itself  the  potentiality  of  pro- 
ducing, amongst  other  things,  all  the  different  kinds  of  spicules 
which  may  happen  to  characterise  the  particular  species  to  which 
it  belongs.  As  development  goes  on  differential  divisions  must 
take  place  whereby  all  the  different  kinds  of  cells  of  which  the 
adult  sponge  is  composed  are  segregated,  and  each  mother-cell 
must  ultimately  retain  the  power  to  secrete  only  one  particular 
kind  of  spicule.  Now  there  is  strong  reason  for  believing  that 
differential  cell-division  is  effected  always  by  the  complex  process 
of  mitosis  or  karyokinesis,  which  concerns  chiefly  the  chromosomes 
of  the  nucleus,  and  hence  I  think  we  may  pretty  safely  conclude 
that  specific  differences  in  the  form  of  the  microscleres  must 
depend  upon  differences  in  the  constitution  of  the  nuclei  of  the 
mother-cells,  or,  in  other  words,  that  the  nuclei  of  the  mother- 
cells  determine  to  a  large  extent  the  form  of  the  microscleres. 

There  appear,  in  short,  to  be  three  secondary  factors  concerned 
in  the  production  of  any  particular  form  of  microsclere :  (1)  the 


THE    PRESIDENT'S    ADDRESS.  75 

nature  of  the  material  (opal)  of  which  the  microsclere  is  com- 
posed ;  (2)  the  nature  of  the  medium  in  which  it  is  deposited, 
viz.  the  colloidal  cytoplasm  of  the  cell  ;  and  (3)  the  presence  of 
the  cell-membrane,  by  which  the  growth  of  the  spicule  is  to  some 
extent  restrained  and  guided.  All  three  are,  however,  doubtless 
dependent  upon  the  hereditary  constitution  of  the  mother-cell 
(including,  of  course,  its  nucleus),  for  while  the  mother-cells  in 
siliceous  sponges  secrete  hydrated  silica,  those  of  the  Calcarea 
secrete  carbonate  of  lime,  and  so  on. 

We  have  next  to  inquire  how  it  is  that,  if  the  specific  forms 
of  sponge  microscleres  are  of  no  importance  to  the  sponge,  such 
very  remarkable  forms  should  ever  have  arisen  in  the  course 
of  evolution.  We  have  to  remember  in  this  connection  that  we 
are  dealing  not  merely  with  a  few  isolated  and  unrelated  forms, 
but  with  progressive  evolutionary  series  along  lines  as  definite 
as  any  other  lines  of  evolution  with  which  we  are  acquainted, 
and  which  certainly  seem  to  require  some  directive  force  to 
explain  them.  If  we  were  dealing  with  adaptive  characters  we 
should  at  once  say  that  the  result  was  due,  as  in  the  case  of  the 
megascleres,  to  the  natural  selection  of  small,  fortuitous,  favour- 
able variations  ;  but  the  fact  that  the  characters  in  question  are, 
for  the  most  part  at  any  rate,  not  adaptive,  seems,  at  first  sight 
at  any  rate,  to  rule  natural  selection  out  altogether. 

It  might  be  suggested,  however,  that  the  solution  of  the 
difficulty  is  to  be  found  in  the  well-known  principle  of  correlation. 
In  accordance  with  this  idea  certain  characters  of  an  organism 
are  inseparably  linked  together  with  other  characters  in  such 
a  way  that  any  variation  in  the  one  must  be  accompanied  by 
a  corresponding  variation  in  the  other,  though  the  reason  why 
such  characters  should  be  so  linked  together  is  often  by  no  means 
obvious.  To  upholders  of  such  a  view  as  this  the  analogy  of 
by-products,  upon  which  I  laid  so  much  stress  at  the  beginning 
of  my  address,  may,  I  think,  prove  useful.  Although  I  doubt 
whether  the  hypothesis  of  correlation  is  adequate  to  meet  the 
present  case  completely,  it  certainly  seems  worth  while  to 
examine  it  a  little  more  closely. 

I  may  illustrate  my  meaning  by  reference  to  the  action  of  a 
few  drops  of  acid  upon  an  alkaline  solution  of  litmus.  Two  per- 
fectly distinct  results  will  be  produced.  The  solution  will  become 
acid  and  it  will  change  from  blue  to  red.     You  may  desire  for 


76  the  president's  address. 

some  special  purpose  to  produce  one  of  these  results  only,  but 
they  are  inseparably  connected  and  you  cannot  have  one  without 
the  other.  You  cannot  have  the  result  aimed  at  without  having 
also  the  by-product. 

Now  suppose  some  change  in  the  constitution  of  the  germ- 
plasm  of  an  organism  to  give  rise  to  two  modifications  in  the 
developing  soma  or  body.  We  may  call  the  change  or  modi- 
fication in  the  germ-plasm  GA  and  the  modifications  in  the  soma 
SA  and  Sa.  SA  and  Sa  will  be  inseparably  correlated  with  one 
another  through  GA,  though — as  for  example  in  the  case  of 
white  tom-cats  with  blue  eyes,  which  are  said  to  be  generally 
deaf — the  connection  between  them  may  appear  to  be  quite 
arbitrary. 

Suppose  further  that  SA  proves  to  be  a  useful  character  and 
Sa  a  useless  one.  Then,  under  the  influence  of  natural  selection, 
SA  will  be  preserved  and  may  ultimately  develop  into  a  very 
perfect  adaptation  ;  but,  if  so,  GA  must  also  undergo  further 
modification,  and  this  modification  will  likewise  affect  Set,  which  will 
therefore  keep  pace,  so  to  speak,  with  SA.  Thus  a  non-adaptive 
character  (S«)  may  undergo  progressive  evolution,  which,  though 
in  reality  indirectly  controlled  by  the  action  of  natural  selection, 
may  appear  to  be  guided  by  some  mysterious  vital  force  or 
entelechy. 

Now  suppose  further  that  as  a  result  of  some  change  in 
the  conditions  of  life,  or  merely  as  the  result  of  its  progressive 
evolution  in  some  particular  direction,  So-  in  turn  acquires  some 
value  in  the  struggle  for  existence.  Natural  selection  will,  in 
future,  favour  its  further  development  directly,  and  what  was 
at  first  a  mere  by-product  becomes  an  adaptive  character.  Thus 
adaptive  characters  may  perhaps  become  linked  together  in 
groups,  the  existence  of  each  group  being  dependent  on  some 
particular  property  of  the  germ-plasm  through  which  all  the 
members  of  the  group  are  connected. 

At  the  same  time  non-aclaptive  characters  may  persist  side 
by  side  with  adaptive  ones,  and  even  harmful  variations  may 
persist  if  their  injurious  effects  are  counterbalanced  by  useful 
characters  with  which  they  happen  to  be  correlated  and  which 
cannot  exist  without  them.  Inasmuch,  however,  as  two  useful 
characters  are  more  valuable  than  one,  natural  selection  will 
tend  to  favour  the  correlation  or  linking  together  of   adaptive 


THE    PRESIDENT'S    ADDRESS.  77 

characters,  and  this  is  perhaps  the  reason  why,  in  the  higher 
organisms,  non -adaptive  characters  are  less  frequently  met  with 
than  in  lower  forms.  Moreover,  the  effect  of  natural  selection 
will  tend  to  become  cumulative  and  the  rate  of  evolution  corres- 
pondingly increased. 

It  may  be  objected  that  even  in  the  highest  organisms 
characters  often  vary  independently  of  one  another,  but  who 
knows  how  many  characters  are  really  involved  in  each  such 
variation  ?  Moreover,  it  by  no  means  follows  from  what  has 
been  said  above  that  new  characters,  whether  valuable  or 
otherwise,  may  not  arise  singly  and  remain  quite  independent 
of  others. 

In  any  case  the  principle  of  correlation  could  hardly  help  us 
to  explain  the  specific  forms  assumed  by  sponge  microscleres,  or 
indeed  the  exact  nature  of  any  non-adaptive  character ;  it  could 
only  help  to  explain  why  such  characters  should  exist  at  all  and 
why  they  should  undergo  progressive  evolution. 

If  it  be  asked,  what  are  the  adaptive  characters  with  which, 
in  our  own  particular  case,  the  non-adaptive  characters  of 
the  microscleres  are  supposed  to  be  correlated  ?  it  must  be 
admitted  that  this  question  cannot — at  any  rate  at  present — be 
answered,  but  it  would  be  sufficient  for  the  general  argument  if 
it  were  granted  that  a  modification  in  the  constitution  of  the 
germ -plasm  which  gives  rise  to  a  useful  character  may  at  the 
same  time  give  rise  also  to  a  useless  one,  or  perhaps  even  to 
many  useless  ones. 

The  question,  why  are  the  specific  forms  of  sponge  microscleres 
what  they  are1?  is  probably  one  that  will  have  to  be  answered, 
if  it  ever  is  answered,  by  the  chemist  and  physicist  rather  than 
by  the  mere  biologist ;  or  perhaps  by  that  happy  combination 
of  chemist,  physicist  and  biologist  whose  advent  is  so  much 
to  be  desired.  I  have  suggested  that  the  form  is  probably 
determined  by  the  hereditary  constitution  of  the  mother-cell, 
including  its  power  to  select  silica  as  the  raw  material  to  be 
worked  up,  but  this  is  no  more  than  to  say  that  the  nature  of 
the  product  turned  out  by  a  factory  depends  upon  the  character 
of  the  work-people  employed  and  of  the  machinery  and  raw 
material  with  which  they  have  to  deal.  In  the  case  of  our 
microscleres  we  want  to  know  a  great  deal  more  about  the 
nature  of  the  machinery  and  the  manner  in  which  it  is  controlled 


78  the  president's  address. 

before  we  can  hope  to  reach  even  an  approximate  solution  of  the 
problem. 

Some  light  may  perhaps  be  thrown  on  the  subject  by  ex- 
periments such  as  those  of  Leduc  and  others  upon  artificial 
osmotic  growths.  Leduc,  in  particular,  has  succeeded  in  pro- 
ducing very  interesting  growth-forms  by  the  osmotic  action  of 
various  chemical  reagents  in  solution.  Some  of  these  forms  bear 
an  extraordinary  resemblance  to  the  forms  of  living  organisms. 
I  do  not,  of  course,  attribute  much  importance  to  the  particular 
forms  produced  in  this  manner  as  explaining  the  particular 
forms  of  any  living  organisms.  What  they  demonstrate  is  that 
purely  chemical  and  physical  causes  may  give  rise  to  more  or  less 
definite  and  at  the  same  time  non -crystalline  forms  in  colloidal 
media,  and  though  none  of  the  forms  as  yet  produced  come 
anywhere  near  our  sponge-spicules  in  symmetry  or  sharpness  of 
definition,  they  certainly  seem  to  indicate  a  hopeful  line  of 
inquiry.  The  particular  form  produced  depends  upon  the  nature 
of  the  reagents  employed  and  upon  the  conditions  under  which 
the  experiment  is  carried  out.  If  these  always  remain  constant 
we  may  assume  that  the  osmotic  growth  will  always  have  the  same 
form,  but  probably  with  the  means  at  our  disposal  it  would  be 
impossible  to  produce  exactly  the  same  result  twice  over.  The 
remarkable  thing  about  the  sponge  microscleres  is  that  within 
the  limits  of  the  same  species  the  same  results  very  often  are 
exactly  reproduced,  or  at  any  rate  so  exactly  that  we  are  unable 
to  distinguish  between  them.  I  suggest  that  these  results  are 
produced  by  chemical  and  physical  causes,  involved  in  and 
controlled  by  the  hereditary  constitution  of  the  mother-cell, 
and  that  any  modification  of  this  hereditary  constitution  must 
give  rise  to  a  corresponding  modification  in  the  results.  Further 
than  this  I  fear  we  cannot  at  present  venture. 

It  has  frequently  been  objected  to  the  theory  of  natural 
selection  that,  however  much  useful  characters  may  be  en- 
couraged and  fostered  in  the  struggle  for  existence,  it  cannot 
account  for  the  first  appearance  of  such  characters.  This  appears 
to  me  to  be  a  very  fair  criticism.  It  seems  to  me,  also,  very 
misleading  to  speak  of  the  origin  of  species  by  natural  selection, 
for  specific  characters  throughout  the  animal  and  vegetable 
kingdom  are,  I  believe,  generally  non-adaptive,  and  therefore 
cannot  be  directly  due  to  natural  selection.     This  is  certainly  the 


THE    PRESIDENT'S    ADDRESS.  79 

case  with  the  specific  characters  of  sponges,  which,  as  we  have 
seen,  depend  for  the  most  part  upon  trivial  microscopical  differ- 
ences in  the  shape  of  the  spicules. 

Without  entering  upon  the  vexed  question  of  the  relation 
between  somatogenic  and  blastogenic  characters,  we  may  assume 
in  our  ignorance  that  such  characters  as  those  which  we  have 
been  discussing  arise  fortuitously  in  the  germ-plasm,  and  that 
it  is  a  mere  chance  whether  or  not  they  may  prove  to  be  of  any 
value  to  the  organism.  If  they  are  valuable,  natural  selection 
will  foster  and  encourage  them ;  if  they  are  not,  they  may 
nevertheless  persist  for  many  generations  unless  too  injurious  to 
their  possessors.  If  linked  by  correlation  with  useful  characters 
they  may  be  indirectly  fostered  by  natural  selection,  and  un- 
dergo a  course  of  evolution  parallel  to  that  of  their  correlative 
characters.  Although  they  may  be  useless  at  first,  they  may 
acquire  some  special  value  under  new  conditions  of  life,  or  in 
the  course  of  their  evolution  under  the  old  conditions,  and  then 
natural  selection  will  begin  to  act  upon  them  directly.* 

Possibly  all  the  characters  which  an  organism  exhibits,  with 
the  important  exception  of  those  which  are  due  to  the  effects 
of  use  and  disuse  of  organs,  or  to  the  response  of  the 
organism  in  some  other  way  to  the  direct  action  of  the  environ- 
ment, have  first  arisen  as  by-products  of  the  complex  chemical 
and  physical  processes  upon  which  the  life  of  the  organism 
depends. 

There  is  one  more  aspect  of  the  problem  to  which  I  should  like 

*  Having  been  asked  to  give  a  definite  example  of  a  character  which, 
at  first  useless,  has  ultimately  acquired  an  adaptive  value,  I  suggest  the 
pattern  of  the  venation  on  the  front  wings,  or  tegmina,  and  on  the  leaf-like 
outgrowths  of  the  abdomen  in  the  leaf-insect  Pulchriphyllium  cvurifoliuvi. 
This  venation  so  closely  resembles  that  of  a  leaf  as  greatly  to  increase 
the  remarkable  protective  resemblance  which  undoubtedly  enables  the 
insect  to  conceal  itself  effectively  from  its  enemies.  The  mere  pattern 
of  the  venation  in  the  more  primitive  and  typical  Orthoptera  can  hardly 
have  had  any  selective  value.  Of  course  the  venation  itself  must  always 
have  been  useful,  both  for  supporting  the  wings  and  for  supplying  them  with 
air,  etc. ;  but  as  regards  the  pattern  which  the  venation  makes  (which  is 
the  character  to  which  I  refer)  one  type  of  arrangement  would  seem  to 
have  been  as  good  as  another  until  it  acquired  a  special  adaptive  value 
as  a  factor  in  bringing  about  protective  resemblance  to  a  leaf,  and  then 
doubtless  the  pattern  evolved  under  the  influence  of  natural  selection  until 
it  reached  its  present  degree  of  perfection. 


80  THE    PRESIDENT'S    ADDRESS. 

to  direct  your  attention  before  concluding.  The  constancy  in 
the  specific  form  of  the  microscleres  of  the  Tetraxonida  appears 
to  be  much  greater  in  the  case  of  the  sigmatose  than  in  that  of 
the  astrose  series,  and  in  the  former  at  any  rate  seems  to  point 
to  the  different  modifications  having  arisen  as  mutations  rather 
than  as  fluctuating  variations.  This  would,  I  think,  be  quite 
in  harmony  with  the  views  which  I  have  been  endeavouring  to 
express.  A  mutation,  however  small  it  may  be,  is  believed 
to  be  due  to  some  change,  apparently  sudden,  in  the  constitution 
of  the  germ-plasm,  which  may  then  remain  without  further 
alteration  until  another  mutation  occurs.  To  say  that  the 
change  in  question  is  probably  of  a  physico-chemical  character 
seems  almost  a  truism ;  but  if  it  is  so  it  seems  only  natural  to 
suppose  that  such  a  modification,  transmitted  by  cell-division 
to  all  the  mother-cells  of  a  particular  kind,  may  affect  in  a 
uniform  manner  the  form  of  all  the  microscleres  deposited  in 
these  mother-cells,  just  as  a  change  in  the  character  of  the 
reagents  employed  will  affect  the  form  of  osmotic  growths  ex- 
perimentally produced.  If  this  view  be  correct,  we  must  suppose 
also  that  any  adaptive  modifications  with  which  the  modifications 
of  the  microscleres  may  possibly  be  correlated  must  also  have 
arisen  as  mutations.  I  see  no  objection  to  such  a  supposition, 
for  mutations,  if  they  occur  sufficiently  frequently,  may  be  quite 
as  valuable  from  the  point  of  view  of  natural  selection  as  small 
fluctuating  variations. 

We  do  not,  of  course,  know  what  may  be  the  cause  of  the 
modification  in  the  constitution  of  the  germ-plasm  that  gives  rise 
to  a  mutation,  but  there  is  some  reason  to  believe  that  it  may 
be  due  either  to  the  permutations  and  combinations  of  ancestral 
characters  which  take  place  in  the  maturation  and  fertilisation 
of  the  germ-cells,  or  to  the  influence  of  some  change  of  environ- 
ment upon  the  germ- plasm.  If  the  characters  of  sponge  spicules 
are  really  of  the  nature  of  mutations  it  should  be  possible  to 
obtain  Mendelian  results  by  hybridisation,  and  I  hope  that 
at  some  time  in  the  future  experiments  may  be  made  with  this 
object  in  view.  The  difficulties  in  the  way  of  carrying  out 
such  experiments  would  probably,  however,  be  very  great,  and 
we  should  require  to  know  a  great  deal  more  than  we  do  about 
the  breeding  habits  and  life-history  of  sponges  before  we  could 
hope  to  bring  them  to  a  successful  issue. 


33 
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THE    PRESIDENT'S    ADDRESS.  81 


Description   of  Plate  7. 

Fig.   1.  Ideal  primitive  tetraxon. 

2.  Plagiotriaene  of  Ecionema  carteri,  x  52. 

3.  Orthotriaene  of  Pilochrota  homelli,  X  52. 

4.  Anatriaene  of  Tetilla poculifera,  X  52. 
4a.  Cladome  of  4  x  230. 

5.  Protriaene  of  Tetilla  pocidifera,  x  52. 
5a.  Cladome  of  5  x  230. 

6.  Dichotriaene  of  Ecionema  laviniensis,   x  52. 
„     6a.  Cladome  of  6,  seen  from  above,   x  52. 
,,     la-Id.  Ends  of  triaenes  of  Stelletta  vestigium,  with  reduced 

cladi,   x  230. 
,,     8.     End  of  oxeote  of  Stelletta  vestigium,  x  230. 
,,     9.     Angulated  oxeote  of  Pachychalina  subcylindrica,   x  360. 
„   10.     Straight  oxeote  of  Reniera  pigmentifera,  x  360. 
,,   11.     Style  of  Axinella  halichondrioides,  x  230. 
„   12.     Tylostyle  of  Hymedesmia  curvistellifera,  X  230. 
„   13.     Spined  tylostyle  of  Myxilla  tenuissima,  x  530. 
,,   14a-14A.  Astrose  microscleres  of   Xenospongia  patelliformis, 

X  530. 
„    15.      Microxeote  microsclere  of  Desmacella  tubidata,  x  230. 
„    16.     Toxiform  microsclere  of  Gellius  angulatus  var.  canalicu- 

lata,  x  230. 
„    17a,  lib.  Sigmata  of  Gellius  angulatus  var.  canalicidata,  x  230. 

(Note  the  angulation  of  the  spicule,  suggesting 

derivation  from  a  diactinal  microxeote,  such  as  is 

represented  in  figs.  26a-26c.) 
18a,  186.   Toxa  of  Toxochalina  robusta  var.  ridleyi,  X  230. 

19.  Sigma  of  Desmacidon  reptans,  X  512. 

20.  End  of  sigma  of  Paresperella  serratohamata,  x  530. 

21.  Diancistron  of  Vomerula  or  Hamacantha,  x  about  200. 

22.  Isochela  of  Esperiopsis  pulchella,  front  view,  x  284. 
,,  22a.  Side  view  of  same,  x  284. 

„  23.     Anisochela  of  Cladorhiza  jientacrinus,  front  view,  x  700. 
,,  23a.   Side  view  of  same,  x  700. 
„  24.     Anisochela    of    Cladorhiza  (?)     tridentata,    front    view, 

x  360. 
„  24a.  Side  view  of  same,  x  360. 
Journ.  Q.  M.  C,  Series  II.— No   72  6 


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33 
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82  the  president's  address. 

Fig.  25.     Primitive  tetraxon  (calthrops)  of  Dercitopsis  ceylonica, 
x  230. 
„    26a-26c.  Small  oxea  of  Dercitopsis  ceylonica,  x  230.  (Oxea 
four  or  five  times  as  large  occur  in  the  same 
sponge.) 

(Figs.  2-186,  20,  25-26c,  from  Dendy's  Report  on  the  Sponges 
collected  by  Prof.  Herdman  at  Ceylon  in  1902.     Figs.  19,  21,  22, 
22a,  24,  24a,  from  Ridley  and  Dendy's  Report  on  the  Challertgo 
Monaxonida.     Figs.  23,  23a,  from  Dendy  in  Ann.  <&  Mag.  Nat. 
Hist.,  Ser.  5,  vol.  20,  PI.  xv.) 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  72,  April  1913. 


Journ.dM.C 


Ser.2yol.XlI 


Spicules  of   Tetra-xorud  Sponges. 


83 


ON    FIVE   NEW  SPECIES   OF   BDELLOID   ROTIFERA. 

By  David  Bryce. 

{Read  March  2oth,  1913.) 

Plates  8  &  9. 

The  five  species  of  which  descriptions  are  furnished  in  the  present 
paper  have  been  known  as  distinct  forms  for  many  years  past, 
although  their  distinguishing  characteristics  have  not  hitherto 
been  gathered  into  the  formal  diagnosis  which  constitutes  scientific 
baptism.  Four  of  them  belong  to  that  important  section  of  the 
Philodinidae  in  which  the  food  is  formed  into  pellets  after  passing 
through  the  mastax,  and  are  assigned  to  the  genus  Habrotrocha. 
The  fifth  species  belongs  to  the  more  numerous  section  of  the 
same  family  in  which  the  food  is  not  at  any  time  agglutinated 
into  pellets,  and  being  oviparous  and  possessed  of  three  toes  is  a 
member  of  the  genus  Callidina,  as  now  restricted. 

Under  the  name  of  Habrotrocha  munda,  I  describe  the  form  to 
which  T  referred  in  some  remarks  upon  the  identity  of  Callidina 
elegans  Ehrbg.,  appended  to  my  paper  on  "  A  New  Classification 
of  the  Bdelloid  Rotifera,"  *  as  having  been  wrongly  identified  as 
that  species  by  Hudson  and  Gosse  and  by  other  writers.  I  have 
endeavoured  in  that  place  to  show  as  clearly  as  possible  my 
reasons  for  the  belief  that  this  form  cannot  be  that  which  Ehren- 
berg  described ;  and  inasmuch  as  none  of  the  various  correspondents 
who  have  addressed  me  with  regard  to  my  classification  have 
advanced  a  view  contrary  to  my  own  in  this  matter,  I  think 
that  this  victim  of  mistaken  identity  may  now  be  established  on 
a  firmer  and  less  assailable  basis. 

This  species  is  the  most  common  of  the  few  pellet-making  forms 
which  have  their  usual  habitat  in  ponds  and  ditches.  In  fresh 
gatherings  it  may  frequently  be  seen  swimming  vigorously  with 
its  head  slightly  deflexed,  or  perhaps  marching  about  at  a  great 

*  Jaimi.  Q.  M.  C,  Ser.  2,  Vol.  XI.,  p.  61. 


84       D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA. 

pace,  and  will  often  attract  attention  from  the  bright  reddish 
colour  of  the  stomach  wall.  On  closer  examination  it  may  be 
readily  recognised  from  the  peculiar  shape  and  pose  of  the  spurs, 
which  are  quite  distinctive,  and  from  the  many-toothed  rami. 
Under  more  natural  conditions,  it  takes  shelter  in  any  convenient 
recess  among  debris  or  in  leaf  axils,  and  there  makes  its  home, 
protruding  the  head  and  neck  when  it  desires  to  feed. 

The  second  species,  Habrotrocha  torquata,  has  similar  many- 
toothed  rami,  but  in  several  other  respects  differs  distinctly  from 
H.  munda.  I  believe  that  in  some  quarters  it  has  also  been 
accepted  as  Callidina  elegans  Ehrbg.,  probably  on  account  of  the 
rami.  Unlike  H.  munda,  it  is  never  found  in  ditches  or  ponds, 
but  has  its  habitat  usually  in  mosses  growing  in  positions  fre- 
quently wet.  The  spurs  are  of  simple  form  and  the  stomach  wall 
is  never  of  reddish  tint.  It  has  not  been  observed  to  seclude  itself 
in  any  way  and  is  of  comparatively  quiet  habit.  Its  specific 
name  was  suggested  by  a  curious  but  illusory  appearance  in  some 
positions  of  an  annulus  encircling  the  expanded  corona. 

The  third  of  the  pellet-making  species,  Habrotrocha  spicida,  is  a  " 
rather  smaller  form,  which  has  the,  so  far,  unique  distinction  of  a 
single  spine  of  small  size  placed  on  the  pre-anal  segment  on  the 
median  dorsal  line.  When  the  body  is  contracted,  or  when  the 
animal  is  seen  in  lateral  view,  this  spine  is  sufficiently  obvious, 
but  at  other  times  it  is  most  easily  overlooked.  In  my  own 
experience  this  Bdelloid  has  only  occurred  in  hilly  country  in 
elevated  positions,  but  I  learn  from  Mr.  James  Murray  that  he 
has  also  met  with  it  in  lowland  habitats. 

The  fourth  species,  Habrotrocha  ligida,  is  one  of  those  puzzling 
forms  which  can  only  be  recognised  with  certainty  when  it  is  feed- 
ing. It  is  mainly  distinguished  by  the  possession  of  a  small  fleshy 
tooth,  which  stands  erect  in  front  of  the  narrow  sulcus  between  the 
two  pedicels  of  the  corona,  difficult  to  discern  except  in  direct  dorsal 
view.     In  other  respects  it  offers  little  to  remark. 

For  my  earliest  knowledge  of  the  new  Callidina,  I  am  indebted 
to  my  esteemed  correspondent  the  late  Forstmeister  L.  Bilfinger, 


D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA.       85 

of  Stuttgart,  who  sent  to  me,  as  long  ago  as  1894,  a  sketch  of  the 
animal  together  with  some  moss  in  which  it  occurred.  I  have 
therefore  given  it  the  specific  name  Bilfingeri,  in  honour  and  in 
grateful  appreciation  of  a  most  courteous  correspondent  and  of  a 
painstaking  and  careful  observer  of  the  Rotifera.  The  type  form 
of  this  species  is  marked  by  a  series  of  lateral  and  dorsal  knob- 
like prominences  on  the  posterior  half  of  the  trunk.  As  in  most 
other  species  with  such  knobs  or  with  spines,  the  presence  of  these 
ornaments  is  not  constant,  and  occasional  examples  are  found  in 
which  some  or  even  all  the  typical  prominences  are  absent. 

Habrotrocha  munda  sp.  no  v.  (PI.  8,  fig.  1). 

Specific  Characters. — Corona  moderately  wide,  exceeding  collar  ; 
pedicels  with  dorsal  inclination  ;  discs  more  strongly  inclined  in 
same  direction.  Under  lip  relatively  high,  centrally  prominent 
and  spoutlike,  Dorsal  antenna  long.  Rami  with  seven  or 
more  fine  teeth.  First  foot  joint  with  dorsal  prominence.  Spurs 
resembling  caudal  processes  of  Chaetonotus. 

In  general  build  and  in  the  somewhat  "  smothered  "  appearance 
of  the  corona,  due  in  this  case  to  the  shortness  of  the  pedicels  and 
to  the  very  oblique  setting  upon  them  of  the  trochal  discs,  this 
species  has  a  certain  resemblance  to  Habrotrocha  torquata,  but 
can  usually  be  distinguished  from  it  by  the  shape  of  the  spurs, 
which  in  typical  specimens  have  a  very  characteristic  moulding 
and  pose.  In  the  normal  or  extended  position,  the  body  is  spindle- 
shaped,  distinctly  larger  about  or  a  little  behind  the  centre,  and 
smaller  at  either  extremity,  and  rarely  exceeds  320  /x  in  length. 
While  the  rostrum  is  shorter  and  thicker  than  usual,  the  head 
and  neck  are  only  moderately  stout,  the  trunk  being  distinctly 
larger  (sometimes  almost  swollen  when  well  fed),  the  lumbar 
segments  short  and  tapering  rapidly  to  a  relatively  small  and 
slender  foot  of  (I  think)  three  segments.  When  creeping,  the 
dorsal  and  lateral  longitudinal  skin-folds  are  usually  well  marked. 
In  adult  examples  the  stomach  wall  is  frequently  of  a  vivid 
reddish  colour,  and  the  lumen  of  the  stomach  is  usually  crammed 


86       D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID   ROTIFERA. 

with  obvious  food  pellets.  The  first  foot  segment  has  a  median 
dorsal  prominence  of  moderate  height,  rather  wider  than  long, 
and  best  seen  in  lateral  view.  The  second  segment  has  the  very- 
characteristic  spurs,  which  always  suggest  to  me  the  caudal 
processes  of  the  common  form  of  Chaetonotus.  They  are  longer 
than  is  customary  among  pellet-making  species,  frequently 
measuring  14  to  15  /x  in  length,  but  are  sometimes  much  shorter. 
Near  the  base  they  are  swollen  on  the  inner  side,  and  closely 
approximate.  About  mid-length  they  suddenly  diminish  in 
thickness  and  are  thence  produced  to  rather  acute  points.  The 
outer  side  of  each  is  nearly  straight,  and  they  are  held  at  a 
slightly  divergent  angle.  The  three  toes  are  difficult  to  see,  but 
the  terminal  pair  (and  I  think  the  dorsal  toe"  as  well)  are 
moderately  long  and  acute.  The  dorsal  antenna  is  sometimes 
quite  25  fx  long  and  is  carried  much  as  in  Rotifer  macrocerost 
being  inclined  backwards  when  the  animal  is  creeping  about,  and 
directed  more  or  less  forward  when  it  is  feeding. 

The  corona  attains  a  width  of  about  45  li.  The  trochal  discs 
are  separated  by  a  shallow  furrow,  which  narrows  to  a  mere 
notch  as  it  nears  the  ventral  side.  On  that  side  accordingly  the 
principal  wreath  is  almost  uninterrupted,  and  in  place  of  the 
customary  appearance  in  front  view  of  two  distinct  "  wheels  '' 
there  is  rather  that  of  a  toothed  band  passing  rapidly  round  a. 
single  transversely  elliptic  course,  distinctly  broken  on  the  dorsal 
side  and  only  slightly  indented  on  the  ventral.  In  lateral  view 
it  is  seen  that  the  pedicels  are  dorsally  inclined,  short  and 
obliquely  truncate,  so  that  the  trochal  discs  are  still  more  inclined 
towards  the  dorsal  side.  The  under  lip  and  mouth  margins  are 
high  in  relation  to  the  discs,  and  the  former  centrally  prominent 
and  spout-like  as  in  Habrotrocha  angusticollis,  but  in  a  lesser 
degree.  The  upper  lip  is  usually  hidden  by  the  reverted  rostrum. 
So  far  as  I  have  been  able  to  discern,  it  rises  moderately  towards 
the  centre  and  is  neither  bilobed  nor  reflexed.  The  rami  are 
about  19  fx  in  length,  somewhat  triangular  in  outline,  and  have 
each  at  least  seven  very  fine  teeth. 


D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA.       87 

Habrotrocha  munda  occurs  most  frequently  in  pools,  especially 
when  water-mosses  and  anacharis  are  present.  I  have  also  found 
it  occasionally  in  sphagnum  and  in  confervae,  both  in  floating 
masses  and  in  the  growth  upon  submerged  stones.  In  suitable 
situations  it  makes  for  itself  a  rough  case  or  nest  of  the  same  type 
as  that  produced  by  Rotifer  macroceros. 

It  is  of  cosmopolitan  distribution.  I  have  noted  it  for 
England,  Scotland,  Germany  (Baden,  Black  Forest,  Wurtemberg, 
Stuttgart),  Cape  Colony. 

Habrotrocha  torquata  sp.  nov.  (PL  8,  fig.  2). 

Specific  Characters. — Of  medium  size  and  stoutness.  Corona 
equal  to  or  rather  exceeding  collar ;  pedicels  short,  distinct ; 
trochal  discs  more  or  less  dorsally  inclined.  Upper  lip  moderately 
high,  undivided  but  centrally  slightly  reflexed ;  under  lip 
unusually  high,  yet  scarcely  prominent.  Dorsal  antenna  rather 
long.  Kami  with  six  or  more  fine  teeth.  Spurs  short,  divergent, 
conical. 

When  creeping  about,  H.  torquata  is  somewhat  difficult  to 
recognise,  as  it  lacks  any  conspicuous  peculiarities  of  form,  colour 
or  size.  It  is  perhaps  most  usefully  described  by  comparison  with 
other  species  of  the  same  genus  having  similar  many-toothed 
rami.  The  body  is  of  moderate  dimensions,  less  spindle-shaped 
than  in  H.  munda,  but  less  parallel-sided  than  in  H.  elegans 
(Milne).  The  rather  short  foot  is  longer  and  more  distinct  than 
in  the  latter  species,  but  is  less  so  than  in  H.  constricta  (Duj.). 
The  spurs  are  simple  short  cones  of  moderate  stoutness,  and  are 
held  at  almost  a  right  angle,  differing  thus  from  the  slighter  and 
widely  divergent  spurs  of  H.  constricta,  the  short,  peg-like,  very 
slightly  divergent  spurs  of  H.  elegans  (Milne)  and  the  com- 
paratively long  moulded  spurs  of  H.  munda.  In  most  examples 
the  stomach  is  not  obviously  tinted,  but  is  occasionally  of  a 
yellowish  colour,  yet  never  of  the  reddish  shade  frequent  in 
H.  munda,  H.  auricidata,  and  other  species. 

In  habit  it  resembles  H.  constricta ;  that  is  to  say,  it  lives  in  the 


88       D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA. 

open  and  is  not  a  dweller  in  the  shelter  afforded  by  natural  or 
contrived  gatherings  of  dirt  particles  or  debris  like  H.  elegans 
(Milne)  and  H.  munda.  I  have  never  met  with  it  in  pools,  but 
usually  in  mosses  (not  sphagnum)  growing  in  wet  positions. 
When  the  corona  is  displayed,  it  is  seen  to  have  a  quite  unusual 
appearance.  As  in  H.  munda,  the  trochal  discs  are  inclined 
towards  the  dorsal  side,  but  in  a  varying  degree,  and  are 
separated  by  a  furrow  deeper  than  in  that  species.  The  upper 
lip  rises  in  a  broad  rounded  lobe  which  is  centrally  bent  back, 
leaving  visible  the  fleshy  connection,  or  nexus,  between  the  short 
pedicels.  On  the  ventral  side  the  under  lip  rises  unusually  high, 
and  thus  in  dorsal  view,  the  collar,  which  passes  round  the 
pedicels  on  either  side  and  merges  gradually  into  the  under  lip, 
has  an  obliquely  upward  direction,  not  obliquely  downward  as 
customary.  This  results  in  the  optical  presentments  of  the 
rapidly  beating  cilia  of  the  secondary  wreath  (those  lining  the 
collar  and  passing  round  to  the  mouth),  and  of  the  cilia  of  the 
principal  wreath  (those  of  the  trochal  discs),  being  to  some  extent 
commingled,  and  there  is  the  appearance  of  an  annulus  or  ring 
passing  round  the  trochal  discs  immediately  below  their  margins. 
When  the  discs  are  seen  so  that  their  planes  are  nearly 
coincident  with  the  line  of  sight,  they  appear  to  have  deeply 
grooved  margins,  but  the  exact  appearance  varies  with  the  angle 
at  which  they  are  viewed.  Whether  the  appearance  be  that  of  a 
ring  or  of  discs  with  deeply  grooved  margins,  it  is  in  my  opinion 
purely  an  optical  effect  arising  from  the  mutual  interference  of 
the  light  rays  from  the  two  wreaths  of  cilia. 

The  high  under  lip  is  unusually  flat  and  inconspicuous ;  the 
lateral  margins  of  the  mouth  are  scarcely  thickened  and  the 
mouth  cavity  is  small  as  compared  with  that  of  other  Philo- 
dinidae.     When  feeding  the  lumbar  plicae  are  well  marked. 

The  foot  represents  about  one-ninth  of  the  total  length.  It 
has  four  joints,  the  first  having  dorsally  a  distinct  thickening  of 
the  hypodermis. 

In  the  confinement  of  a  small  cell  H.  torquata  proved  only 


D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA.       89 

moderately  hardy.  After  a  few  days,  most  specimens  would 
feed  freely  under  the  unaccustomed  light  and  would  remain 
quiet,  but  I  have  never  known  eggs  to  be  laid  under  such 
conditions. 

By  no  means  a  common  species,  yet  widely  distributed ;  I  noted 
it  first  in  moss  sent  me  in  1895  by  Forstmeister  L.  Bilfinger, 
of  Stuttgart.  I  have  since  found  it  in  moss  from  Epping  Forest, 
Essex ;  Chagford,  Devon ;  Pass  of  Leny,  Perthshire ;  Black 
Forest,  Baden. 

Dimensions. — Greatest  length  410  fx,  more  frequently  320  to 
350  fx.     Corona  38  to  41  /x.     Kami  about  15  fx.     Spurs  6  to  9  /x. 

Habrotrocha  spicula  sp.  nov.  (PI.  9,  fig.  1). 

Specific  Characters. — A  single,  short,  blunt  spine,  sub-erect 
upon  dorsal  median  line  of  pre-anal  segment.  Corona  small, 
13-18  [x  wide;  pedicels  adnate;  upper  lip  high,  rounded,  un- 
divided. Rami  with  four  teeth  each.  Spurs,  short  cones,  widely 
separated. 

A  rather  small  species,  chiefly  noteworthy  for  the  solitary 
spine  and  its  unusual  position.  No  other  Bdelloid  yet  known 
has  only  a  single  spine  or  has  spines  only  upon  the  pre-anal 
segment  as  in  this  case.  When  the  animal  is  in  its  most 
retracted  position,  as  one  usually  sees  it  lying  inert  among  moss 
debris,  the  spine  stands  out  distinctly  at  the  hinder  end  of  the 
body,  and  it  is  also  well  shown  when  the  animal  is  feeding  and 
assumes  the  squatting  position  natural  to  many  species.  It  is 
easily  overlooked  when  the  animal  is  crawling  about  unless  a 
good  side-view  is  presented.  It  springs  from  a  thickened  base, 
and  is  rather  blunt,  short  and  slightly  bent. 

When  seen  from  the  front  the  very  small  corona  is  nearly 
circular  in  outline,  the  trochal  discs  being  separated  by  a  shallow 
furrow  and  the  pedicels  adnate.  In  dorsal  view  the  high 
rounded  upper  lip  rises  quite  to  the  level  of  the  trochal  discs, 
and  its  apex  indeed  is  visible  in  ventral  view.  The  margins  of  the 
mouth  have  small  angular  lateral  prominences,  which  are  partly 


90      D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA. 

visible  even  from  the  dorsal  side  and  add  to  the  apparent  width 
of  the  collar. 

When  extended  the  body  is  moderately  stout  and  the  longi- 
tudinal skin-folds  are  well  marked.  In  most  cases  it  is  colourless, 
but  examples  of  a  faintly  reddish  colour  have  been  seen.  The 
antenna  is  short,  but  rather  stout.  The  rami  are  small,  14-15  tt 
long. 

The  foot  tapers  rapidly  and  is  very  short.  In  the  feeding 
position  it  is  usually  hidden  beneath  the  trunk.  It  seems  un- 
suited  for  crawling  on  a  smooth  surface  such  as  glass,  as  the 
animals  have  unusual  difficulty  in  getting  foothold.  The  first 
joint  has  frequently  a  strong  protuberance  on  its  dorsal  side. 
The  spurs  are  very  small  cones  about  3  /x  long  separated  by  an 
interspace  about  6  /x  wide. 

The  largest  examples  measured  were  about  200  jx  long  when 
extended,  but  others  were  from  170  to  185 /x.  My  earliest  speci- 
mens were  found  in  mosses  collected  for  me  on  Cader  Idris  by 
Mr.  D.  J.  Scourfield  in  1895.  Others  came  from  collections  on 
Mickle  Fell  and  on  Snowdon  by  the  same  friend.  In  1898 
I  found  it  in  moss  from  the  top  of  Ben  Ledi,  in  1907  from  the 
top  of  Ben  Vrackie,  both  in  Perthshire ;  and  in  1906  from  tree- 
moss  in  the  woods  above  Triberg  in  the  Black  Forest,  Baden.  It 
has  also  been  found  repeatedly  by  Mr.  James  Murray  in  Scotland 
and  in  many  foreign  habitats. 

Distribution  :  cosmopolitan,  mostly  at  high  elevations. 
Habitat  :  ground,  rock  or  tree-mosses. 

Habrotrocha  ligula  sp.  nov.  (PI.  9,  fig.  2). 

Specific  Characters. — Moderately  slender.  Corona  somewhat 
wider  than  collar ;  pedicels  rather  high,  semi-adnate ;  discs 
separated  by  narrow  sulcus.  Upper  lip  rising  very  slightly  and 
displaying  a  small  fleshy  tooth,  which  near  its  apex  tapers 
suddenly  to  a  point.  Rami  with  four  teeth  each.  Foot  three- 
jointed  ;  spurs  small,  tapering  cones  with  interspace  nearly  equal 
to  their  length. 


D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    ROTIFERA.       91 

A  species  of  rather  less  than  medium  size  which  in  its  extended 
position  offers  no  obvious  character  for  its  recognition.  The 
rostrum  is  short  and  stout,  and  the  dorsal  surface  has  a  distinct 
almost  ridge-like  thickening  of  the  hypodermis,  best  seen  in 
lateral  view.  Its  movements  are  active  when  crawling  about, 
and  when  feeding  it  sways  and  bends  almost  incessantly  in  all 
directions,  the  body  being  well  extended  and  the  upper  foot 
joints  visible.  The  trochal  discs  are  rather  small  and  the 
greatest  width  of  the  corona  little  exceeds  that  of  the  collar.  The 
pedicels  are  adnate  to  nearly  half  their  height  and  are  very 
slightly  divergent.  At  the  dorsal  end  of  the  nexus  between 
them  is  a  small  fleshy  ligule  or  tooth,  which  for  the  most  part  is 
nearly  cylindrical,  but  near  the  tip  tapers  rather  suddenly  to  a 
point.  It  is  so  inconspicuous  that  it  can  rarely  be  seen  except 
in  direct  dorsal  view  and  when  the  animal  keeps  steady  for  a 
brief  interval.  Even  then  the  exact  shape  of  the  ligule  is 
difficult  to  determine,  but  I  think  that  it  differs  somewhat  from 
the  type  of  ligule  possessed  by  any  of  the  few  Bdelloids  in  which 
this  peculiar  ornament  or  organ  has  been  seen.  In  Habrotrocha 
eremita  (Bryce),  in  which  it  was  first  noted,  it  is  a  simple,  short, 
peg-like  tooth,  very  slender  and  tapering  gradually,  and,  to  judge 
from  the  figures  given  by  Murray,  it  appears  to  be  of  the  same 
character  in  Habrotrocha  acornis  Murray  and  Callidina  lepida 
Murray.  In  the  present  species  the  appearance  is  rather  that 
of  a  fleshy  cylindrical  pedestal,  with  a  tapering  point  inset  at 
the  end  of  the  pedestal  as  if  in  a  socket. 

The  upper  lip  rises  in  a  low  curve  about  as  high  as  the  base 
of  the  ligule.  The  rami  have  four  teeth,  but  one  tooth  on  each 
is  much  less  prominent  than  the  others.  I  have  noticed  that 
the  food  pellets  are  rather  small.  Examples  isolated  produced 
eggs  of  oval  outline,  hyaline,  smooth-shelled,  measuring  70  /x  at 
the  longest  by  43  //,  at  the  shortest  diameter. 

I  had  this  species  first  in  1894  from  a  roadside  near  Deal,  and 
in  the  following  year  from  a  wall  in  Bognor ;  in  both  cases  from 
small  button-like  tufts  of  wTall-moss.     I  did  not  see  it  again  until 


92       D.    BRYCE    ON    FIVE   NEW    SPECIES    OF   BDELLOID    ROTIFERA. 

some  few  weeks  ago,  when  it  was  brought  to  me  by  Mr.  G.  K. 
Dunstall,  who  had  obtained  it  from  moss  collected  near  Leith 
Hill,  in  Surrey.  It  is  probably  a  more  common  species  than 
these  three  isolated  records  would  indicate.  It  may  be  that  it 
has  a  partiality  for  small  tufts  of  moss  (which  do  not  invite 
examination),  or  perhaps  its  restlessness  and  the  absence  of  any 
very  obvious  peculiarity  when  marching  about  has  led  to  its 
being  overlooked. 

In  view  of  Murray's  opinion  that  the  presence  of  a  ligule  in 
Bdelloids  is  an  unsafe  specific  character,  as  it  often  appears  in 
species  where  it  is  not  normally  present,  it  must  be  pointed  out 
that,  while  it  may  be  presumed  that  the  ligule  in  Habrotrocha 
ligula  is  fairly  constant,  it  is  by  no  means  impossible  that 
examples  should  occur  in  which  it  might  be  absent,  and  in  that 
case,  if  normal  specimens  were  not  available  for  comparison, 
identification  might  well  be  difficult. 

Dimensions. — Length  about  320  fx.  Corona  30 /x.  Collar  25  /a. 
Ramus  1 7  /x.     Spurs  5  ll. 


Callidina  Bilfingeri  sp.  nov.  (PI.  9,  fig.  3). 

Specific  Characters. — Of  medium  size,  and  moderately  stout, 
posterior  trunk  having  a  series  of  knob-like  prominences. 
Trochal  discs  well  separated,  but  corona  not  exceeding  collar 
width.  Upper  lip  rather  high  and  wide,  with  shallow  central 
depression.  Rami  with  two  teeth  each.  Dorsal  antenna  short, 
about  half  the  neck  thickness.  Foot  three- jointed;  first  joint 
laterally  swollen,  second  very  short,  somewhat  distended  to  form 
sucker-like  disc.  Spurs  very  minute  cones,  with  wide,  slightly 
convex  interspace. 

So  far  as  I  am  aware,  this  rather  well-marked  species,  of 
moderately  stout  build  and  medium  size,  has  been  met  with  only 
in  ground-mosses.  Typical  specimens  are  easily  recognised  from 
the  series  of  knob-like  prominences  which  ornament  the  sides  of 
the  trunk  segments  and  the  dorsal  surface  of  the  rump  segments. 


D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID    R0TIFER4.        93 

The  number  of  these  "knobs"  appears  to  be  very  inconstant, 
as  in  sketches  made  by  Forstmeister  Bil finger,  James  Murray, 
and  myself  it  varies  from  eleven  to  five ;  and  I  was  informed 
by  the  first-named  correspondent  that  he  had  met  with  examples 
without  any  knobs  at  all.  In  such  cases  the  species  can  still  be 
determined  with  moderate  certainty  from  the  peculiar  structure 
of  the  second  foot  joint,  and  the  minuteness  and  wide  separation 
of  the  spurs.  When  the  full  number  of  prominences  are  present 
they  are  distributed  thus  :  the  third  segment  of  the  trunk  (or 
central  portion  of  the  body)  has  one  at  either  side,  close  to  its 
anterior  boundary ;  the  same  segment  and  the  fourth  and  the 
sixth  have  each  one  at  either  side  near  their  posterior  boundaries; 
while  on  the  dorsal  side  of  the  fifth  and  sixth  segments  there  are 
three  more,  arranged  in  a  triangle  (two  in  front  on  the  fifth 
and  one  behind  on  the  sixth  segment,  the  latter  on  the  median 
line).  The  fifth  segment  is  moderately  swollen  laterally.  The 
lateral  knobs  on  the  sixth  segment  (the  anal)  are  more  nearly 
constant  than  the  others.  Those  most  frequently  absent  are 
the  anterior  pair  of  the  third  segment. 

The  first  foot  joint  has  distinct  lateral  swellings,  and  is  per- 
haps swollen  dorsally  as  well.  The  second  joint  is  very  short, 
and  slightly  distended  with  thickened  skin,  forming  a  sucker- 
like disc  from  the  lower  surface  of  which  the  three  short,  broad 
toes  are  protrusible.  The  flange-like  hinder  margin  of  this 
foot  disc  forms  the  slightly  convex  interspace  between  two  very 
minute  spurs. 

When  creeping  about  the  animal  is  seen  to  have  a  short  and 
stout  rostrum.  In  the  feeding  position  the  body  is  somewhat 
flattened,  and  the  dorsal  longitudinal  skin-folds  are  obliterated. 
The  trochal  discs  are  well  separated,  but  the  head  is  stout  and 
the  corona  does  not  exceed  the  collar  width.  The  upper  lip  rises 
rather  widely  and  high,  and  has  a  shallow  central  depression. 
The  rami  are  14  to  16  ^t  long,  and  are  widest  above  the  middle. 
The  anterior  outer  margin  of  each  is  distinctly  thickened,  and 
passes  gradually  into  a  delicate  winglike  expansion  of  the  ramus. 


94      D.    BRYCE    ON    FIVE    NEW    SPECIES    OF    BDELLOID   ROTIFERA. 

As  already  stated,  this  species  was  first  discovered  by  the 
late  Forstmeister  L.  Bilfinger  in  the  vicinity  of  Stuttgart,  and 
notified  to  me  in  1894.  It  was  afterwards  found  by  Mr.  George 
Western,  probably  near  London,  and  in  1904  by  James  Murray, 
near  Fort  Augustus.  In  1906  I  met  with  it  in  moss  gathered 
on  the  bank  -of  a  roadside  ditch  near  Triberg,  in  the  Black 
Forest.  Quite  recently  numerous  examples  have  been  found  in 
moss  collected  by  Mr.  G.  K.  Dunstall  near  Leith  Hill,  Surrey. 

Dimensions. — Length  about  315 /a.     Corona  38  /x.    Collar  41 /a. 

Spurs  1  to  2  /a  (on  inner  edge). 
i 

Description  of  Plates  8  and  9. 

Plate  8. 

Fig.  1.  Habrotrocha  munda  sp.  nov.,  extended,  dorsal  view,  x  350  ; 

la,  head  and  neck,  corona  displayed,  in  lateral  view, 

X  650  ;    lb,   the   same,   in    ventral    view,    x  750 ;     lc, 

mouth,  in  front  view  (diagrammatic). 

„     2.  Habrotrocha  torquata  sp.  nov.    In  feeding  position,  corona 

displayed,  dorsal  view,  x  550  ;  2a,  spurs,  x  1600. 

Plate  9. 

Fig.  1.  Habrotroclut  spicula  sp.  nov.  In  feeding  position,  corona 
displayed,  ventral  view,  x  600 ;  la,  retracted  position, 
X  600  ;  16,  foot  extended,  dorsal  view,  x  800  ;  lc,  ramus, 
X1600. 

,,  2.  Habrotrocha  ligula  sp.  nov.  In  feeding  position,  corona 
displayed,  dorsal  view,  x  480. 

,,  3.  Callidina  Bilfingeri  sp.  nov.  In  feeding  position,  dorsal 
view,  x  350;  3a,  ramus,  x  1600. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  72,  April  1913. 


Joum.QM.C. 


Ser.  2.Vol.XH,P1.8. 


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New  Species  of  Bdelioid  Rotifera. 


Journ.  Q.M.C. 


Ser2.Vol.Xn,P1.9. 


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95 


NOTES. 

A   NEW    LOW-POWER   CONDENSER 

By  Edward  M.  Nelson,  F.R.M.S. 

{Read  November  26th,  1912.) 

The  condensers  which  at  present  are  supplied  with  microscopes 
are  only  suitable  for  low  powers  ranging  from  |  inch  upwards. 
With  powers  lower  than  these  a  difficulty  arises,  for  it  is  not 
possible  to  fill  the  field  with  the  image  of  the  source  of  light 
focused  upon  the  object,  as  it  should  be.  Substage  condensers 
suitable  for  low  powers  are  all  too  short  in  focus,  consequently 
the  image  of  the  source  of  light  is  far  too  small. 

In  these  circumstances  microscopists  have  been,  and  are, 
accustomed  to  waive  critical  illumination  and  employ  the  most 
uncritical  of  all  illumination,  viz.  to  focus  the  image  of  the 
source  of  light  upon  the  front  lens  of  the  objective ;  this  is 
nothing  more  nor  less  than  lantern  illumination,  which  gives 
a  critical  image  of  a  diaphragm  limiting  the  field,  but  of  nothing 
else ;  all  delicate  lines  and  structures  are  coated  with  black 
diffraction  borders. 

The  obstacle  in  the  way  of  using  a  long-focus  condenser  is  that 
there  is  not  sufficient  room  to  focus  it. 

Powell's  No.  1  stand  has  a  good  deal  of  room,  but  not  enough, 
and  other  microscopes  are  simply  nowhere.  Now  the  way  this 
difficulty  may  be  surmounted  is  to  construct  the  condenser  upon 
the  telephoto  principle.  This  has  now  been  done,  and  Messrs. 
Baker  will  show  you  this  evening  a  substage  condenser  they  have 
made  from  my  design  which  has  4  inches  of  focal  length  and 
requires  only  1  inch  of  working  distance.  With  this  condenser 
the  image  of  the  fiat  of  the  flame  bears  the  same  relation  to  a 
4-inch  objective  with  the  large  field  of  a  P.  &  L.  No.  1  A  eye- 
piece, as  the  image  with  one  of  the  ordinary  universal  condensers, 
with  the  top  off,  does  to  a  |  inch  ;  and  this  is  precisely  what 
was  wanted. 

Now  let  us  understand  exactly  what  this  means.  A  4-inch 
objective  has  a  focal  length  of  2|  inches;  with  a  No.  1  A 
eyepiece  the  size  of   the  object  on  the  stage   that   is  embraced 


96  E.    M.    NELSON    ON    MICROSCOPE    CONSTRUCTION 

in  a  field  of  view  is  —$  inch,  therefore  it  is  necessary  for  the 
condenser  to  focus  upon  the  stage  an  image  of  the  flat  of  the 
flame  ■—$  of  an  inch  wide. 

The  condenser  has  a  low  aperture  of  N.A.  0*14,  but  large  enough 
for  the  objectives  for  which  it  is  intended  to  be  used. 


NAVICULA  RHOMBOIDES    AND    ALLIED    FORMS.* 

(Addendum.) 

By  Edward  M.  Nelson,  F.R.M.S. 
{Bead  November  2M7i,  1912.) 

With  reference  to  the  question,  "  What  was  the  Amician  Test?" 
quite  accidentally  I  recently  came  across  a  notice  to  the  effect 
that  the  test  used  by  the  Jurors  at  the  International  Exhibition 
(London,  1862)  was  the  Navicula  ?'homboides  under  the  name  of 
JV.  affinis.  This  of  course  clears  up  all  the  difficulty.  This 
N.  rhomboides  would  have  been  of  the  kind  termed  the 
"  English  "  rhomboides  in  my  paper,  and  would  have  had  72  to 
73  striae  in  0*001  inch. 

ON    MICROSCOPE  CONSTRUCTION   AND  THE  SIDE 
SCREW   FINE  ADJUSTMENT. 

By  Edward  M.  Nelson,  F.R.M.S. 

(Bead  November  26th,  1912.) 

There  is  one  point  which  has  been  overlooked  with  respect  to 
the  evolution  of  the  microscope.  It  is  thought  that  the  modern 
plan  of  placing  the  coarse  adjustment  slide  and  the  body  upon  the 
fine  adjustment  was  the  invention  of  Zentmayer  (1876),  and  that 
it  first  appeared  in  this  country  in  the  Ross-Zen t may er  model. 
This  however  is  not  the  case,  for  Powell  in  1841  invented  this 
plan,  as  well  as  that  of  the  side  pinion  fine  adjustment,  now  so 
much  in  vogue. 

In  the  frontispiece  of  Cooper's  Microscopiccd  Joumcd  an  illus- 
tration of  this  model  will  be  found,  f     Some  years  ago  Mr.  T. 

*  Journal  Q.M.C.,  Ser.  2.  vol.  ii.  p.  93. 

f  This  was  the  first  microscope  Powell  introduced  after  Lealand  had 
joined  the  firm  (vide  Journal  B.M.S.,  1900,  p.  287,  fig.  78). 


AND   THE    SIDE    SCREW    FINE    ADJUSTMENT.  97 

Powell  kindly  showed  me  one  of  these  microscopes,  but  it  had 
escaped  my  memory.  The  coarse  adjustment  was  by  rack  and 
pinion  ;  this  was  not  attached  to  the  limb  by  a  slide,  but  by  a 
kind  of  cradle.  This  cradle  was  pressed  down  by  a  spring  on 
to  a  horizontal  cone,  which  was  moved  by  a  horizontal  fine- 
adjustment  screw,  which  had  a  milled  head  on  each  side  of  the 
limb. 

The  importance  of  this  model  should  be  recognised  by  every  one 
who  uses  a  microscope,  for  not  only  was  it  the  first  microscope 
to  have  a  side  screw,  but  also  it  was  the  first  instrument  in 
which  we  find  the  limb  attached  to  the  foot  on  two  upright 
pillars.  This  double  support  to  the  joint  (now  almost  universally 
used)  was  the  invention  of  George  Jackson  (President  R.M.S. 
1852-3).  Before  this  all  microscopes  that  were  capable  of  being 
inclined  were  attached  to  the  foot  by  a  single  upright  post  and  a 
compass  joint.*  Powell  attached  the  two  pillars  to  a  flat  tripod 
base  by  a  swivel  so  that  the  base  could  be  placed  in  such  a 
position  as  to  give  the  greatest  amount  of  stability  however 
much  the  body  might  be  inclined  (some  makers  in  copying  this 
arrangement  graduated  this  arc  of  rotation  !). 

Ross  copied  this  kind  of  joint  in  the  model  he  brought  out  in 
1843,  but  substituted  two  parallel  flat  plates  for  the  two  pillars  ; 
but  Messrs.  Smith  and  Beck  adopted  the  two-pillar  form  in  their 
1846  model. 

This  microscope  of  Powell's  had  a  Turrell  stage,  a  micrometer 
stage,  an  achromatic  condenser,  Nicol  polarising  and  analysing 
prisms ;  so  it  was  in  its  day  an  instrument  of  a  very  advanced 
type.  In  1843  Powell  &  Lealand  discarded  the  two  pillars  for 
the  gipsy  tripod,  which  is  the  best  form  of  foot  ever  designed.f 

Coming  now  to  modern  times,  horizontal  fine  adjustments  may 
be  placed  in  two  groups,  viz.  (a)  those  with  continuous  motion 
and  (b)  those  without.  The  drawback  which  those  of  the  first 
kind  possess  is  that  the  user  does  not  know  whether  he  is 
focusing  up  or  down  ;  and  the  drawback  which  all  the  second 
kind,  excepting  the  Berger,  have  is  that  of  damage  and  injury  to 
the  delicate  moving  parts  when  they  butt  up  against  a  stop. 
The  Berger  avoids  all  risk  of  damage  from  this  source  by  causing 

*  Some  ancient  non-achromatic  microscopes  had  ball  and  socket  joints, 
but  those  early  forms  are  not  now  under  discussion, 
t  For  fig.  see  Journal  R.M.S.,  1900,  p.  289,  fig.  79 
Journ.  Q.  M.  C,  Series  II.— No.  72  7 


98 


E.    M.    NELSON    ON    MICROSCOPE    CONSTRUCTION. 


an  idle  nut  to  butt  against  a  stop ;  if  this  nut  receives  damage  or- 
strain  to  its  thread  it  is  of  no  importance.  The  first  kind  adopt 
a  continuous  motion  in  order  to  secure  immunity  from  this 
danger,  and  put  up  with  the  great  disadvantage  of  having  a  fine 
adjustment  which  does  not  follow  the  direction  of  the  movement 
of  the  milled  head. 

The  following  simple  device  has  been  designed  to  effectually 
prevent  any  damage  taking  place.  To  the  right  hand  side  of  the 
limb,  where  the  micrometer  drum-head  is  placed,  a  short  piece  of 
tube,  threaded  on  the  outside,  is  fixed,  and  through  it  the  fine 
adjustment  pinion  passes  just  like  the  cannon  pinion  in  a  clock. 


Fig.  1. 


Fig.  2. 


An  idle  nut  works  on  this  screw  in  a  slot  inside  the  micrometer 
drum.  It  is  then  arranged  that  this  nut  will  permit  ten  rotations 
of  the  fine-adjustment  pinion  to  be  made,  and  then  stop  further 
motion  by  butting  either  against  the  side  of  the  limb  or  against 
the  end  of  the  inside  of  the  micrometer  drum.  Figs.  1  and  2  will 
make  this  simple  device  clear  without  further  explanation. 


NOTE    ON    PLEUROSIGMA    ANGULATUM. 

By  Edward  M.  Nelson,  F.R.M.S. 

{Read  January  28th,  1913.) 

About  the  end  of  the  eighties  I  took  a  photomicrograph  of  a 
specimen  of  Pleurosigma  angulation,  which  had  been  broken  in 
a  very  remarkable  manner  so  that  it  was    possible    to   demon- 


E.    M.    NELSON    ON    V LEU RO SIGMA    AStiULATUM.  99 

strate  the  existence  of  two  membranes.  At  one  part  the  upper 
membrane  had  been  torn  away  leaving  the  lower  membrane, 
at  another  the  lower  membrane  had  gone  while  the  upper  was 
left,  the  rest  of  the  valve  having  both  membranes  in  position. 
These  three  photomicrographs  of  the  upper,  lower  and  both 
membranes  were  exhibited  to  the  Club.  No  other  specimen  I 
have  seen  has  been  so  fortunately  fractured  as  to  demonstrate 
both  membranes  so  clearly  as  this  one. 

The  network  in  one  membrane  differs  slightly  from  that  of 
the  other,  so  that  after  a  little  practice  one  is  able  to  state 
whether  the  membrane  under  observation  is  an  upper  or  lower 
membrane.  The  upper  membrane  in  P.  strigosum  resembles 
the  diamond  panes  of  a  leaded  light,  while  the  lower  is  like 
wire  netting,  fig.  3.  In  P.  balticum  and  allied  forms  the  upper 
memb^ine  has   slit-like    apertures    in    longitudinal    rows,  while 

III 


O-go 

Fig.  3.  Fig.  4. 

the  lower  membrane  has  circular  apertures,  fig.  4,  where  the 
circular  apertures  in  the  lower  membrane  are  seen  through 
the  intercostal  silex  of  the  upper  membrane  and  in  a  line  with 
the  bars  between  the  slits. 

Now  at  that  time  it  was  thought,  and  probably  it  is  still 
the  received  opinion,  that  the  lower  membrane  "  eye-spotted  " 
the  upper  membrane ;  by  which  is  meant  that  the  apertures 
in  the  lower  membrane  are  directly  below  those  in  the  upper 
membrane — much  in  the  same  way  as  in  Coscinodiscus  the  eye- 
spot  is  directly  below  the  perforated  cap  at  the  top  of  the  cell. 

Recently,  however,  study  on  P.  angidatum  with  a  Leitz  apo- 
chromat,  y1^  inch  of  1*40  N.A.,  has  caused  me  to  change  my 
opinion,  for  the  apertures  in  the  lower  membrane  can  be  un- 
mistakably seen  below  the  intercostals  of  the  upper  membrane, 
and  this  is  true  not  only  of  P.  angidatum,  but  also  of  all  allied 
forms  that  have  been  examined. 

No  mention  has  been  made  of  Mr.  T.  F.  Smith's  observation. 


100  E.    M.    NELSON    ON    PLEUROSIGMA   ANGULATUM. 

on  the  structure  of  the  genus  Pleurosigma,  because  this  note, 
not  being  an  exposition  of  the  structure  of  this  genus,  deals 
merely  with  the  single  fact  of  my  altered  opinion  with  regard 
to  the  apertures  in  the  lower  membrane  not  "  eye-spotting  " 
those  in  the  upper. 

The  genus  Pleurosigma  has  been  seventy  years  before  the 
microscopical  world,  not  laid  aside,  but  worked  at  continuously 
by  the  most  skilful  microscopists,  yet  all  the  problems  con- 
nected with  their  structure  have  not  been  solved.  It  is  only 
by  recording  from  time  to  time  a  little  bit  here  and  a  little 
bit  there,  and  by  putting  these  little  bits  together,  that  complete 
and  accurate  knowledge  of  this  difficult  subject  will  be  attained. 

ACTINOCYCLUS  RALFSII   AND   A   COLOURED    COMA. 

By  E.  M.  Nelson,  F.R.M.S. 
{Read  January  28th,  1913.) 

The  following  account  of  a  microscopical  phenomenon,  never 
previously  observed,  may  be  of  interest. 

When  working  on  a  mixed  diatom  gathering,  dry  and  un- 
covered, with  a  Powell  &  Lealand  |  inch  and  a  lieberkuhn,  there 
appeared  round  an  Actinocyclus  Ralfsii  a  wide  border  of  brilliant 
orange,  green  and  blue  light.  The  inside  of  the  valve  was 
uppermost  and  the  bottom  of  the  cup  was  in  focus,  so  that  the 
surrounding  mist  was  caused  by  the  out-of -focus  edge,  which,  of 
course,  was  at  a  higher  level.  Any  one  seeing  this  coloured  mist 
would  have  exclaimed  what  a  badly  corrected  objective  !  but  if 
they  had  looked  at  the  other  diatoms  in  the  field,  they  would 
have  seen  that  the  out-of -focus  coma  was  white  !  The  colour, 
then,  must  be  a  function  of  the  Actinocyclus.  Another  objective 
with  a  lieberkuhn,  viz.  a  Powell  &  Lealand  T4^  inch,  was  tried  on 
the  same  diatom  ;  the  border  was  now  red,  the  green  and  blue 
having  gone  !  A  third  objective,  viz.  a  Wenham  |  inch  with 
lieberkuhn  (really  a  T4<y  inch),  and  the  image  seen  had  no  colour ! 

Here,  then,  we  have  an  example  of  an  object  affecting  different 
objectives  differently.  Would  some  of  our  "  brass  and  glass " 
experts  kindly  take  this  matter  up  ? 

Joara.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  72,  April  1913. 


101 


NOTICES   OF   BOOKS. 

Problems  of  Life  and  Reproduction.  By  Marcus  Hartog, 
M.A.,  D.Sc.,  F.L.S.  8  x  5J  in. ;  xx  -f  362  pages ;  one 
plate,  41  figures  in  the  text,  and  three  diagrams.  London : 
John  Murray,  1912.     Price  7s.  6d.  net. 

In  taking  up  this  book  one  cannot  avoid  a  feeling  of  regret 
that  the  author  was  unable  to  carry  out  his  original  intention  of 
writing  a  general  treatise  on  Reproduction  suited  to  the  layman 
interested  in  biological  questions.  By  his  researches  the  author 
would  have  been  well  fitted  for  such  a  task.  As  it  is,  the  book 
consists  of  a  series  of  papers  on  debatable  subjects  in  Biology 
gathered  from  various  scientific  journals  and  reviews,  and  ranging 
in  date  from  1892  to  1910.  They  have  been  revised  in  part  in 
the  light  of  more  recent  research,  and  brought  up  to  date. 

There  is  much  to  interest  the  microscopist,  and  to  one  who  is 
not  already  acquainted  with  them  in  their  original  form  they  may 
be  recommended.  The  earlier  papers  deal  with  the  problems 
of  reproduction  as  presented  in  the  Protista — conjugation  and 
rejuvenescence  and  the  beginnings  of  sexual  reproduction  or 
syngamy.  The  paper  on  Fertilisation  contains  a  large  number 
of  interesting  facts  gathered  together ;  here  the  author  puts 
forward  the  idea  that  it  is  the  linin  and  not  the  chromatin 
(which  only  serves  a  purely  mechanical  function)  which  is  the 
real  transmitter  of  inherited  properties.  This  idea  is  more 
fully  developed  in  Chapter  1Y.  on  "  Mitokinetism " — a  new 
force  which  the  author  brings  to  our  aid  in  explaining  the 
mechanics  of  the  mitotic  process  of  nuclear  division.  Other 
chapters  deal  with  heredity  and  the  inheritance  of  acquired 
characters  and  Mechanism  and  Life. 

There  are  a  number  of  illustrations  and  a  coloured  plate;  a 
full  index  is  provided. 


102  NOTICES    OF    BOOKS. 

The  Beginner's  Guide  to  the  Microscope,  with  a  section  on 
mounting  slides.  By  Charles  E.  Heath,  F.R.M.S.  1\  x 
5  in.  119  pages,  45  figures  in  text.  London:  Percival 
Marshall  &  Co.,  1912.     Price  Is.  net. 

In  this  elementary  guide  to  the  study  of  Microscopy  the  author- 
has  treated  the  subject  from  a  practical  point  of  view,  leaving 
theoretical  matters  to  the  larger  books  on  the  subject.  With  this 
little  book  at  hand  the  beginner  cannot  fail  to  gain  a  useful 
knowledge  of  the  instrument,  its  care  and  its  application.  The 
methods  of  illumination,  including  the  dark-ground  method,  are 
fully  dealt  with.  As  the  author  says,  the  book  is  intended  "  to 
enable  an  ordinary  man  in  an  ordinary  way  to  interest  himself 
and  his  friends  by  giving  sufficient  instruction  to  make  him  capable 
of  seeing  and  showing  some  of  the  hidden  wonders  "  revealed  by 
the  microscope. 


103 


PROCEEDINGS  \fy 

OF    THE 

QUEKETT   MICROSCOPICAL  CLUB. 

At  the  meeting  of  the  Club  held  on  October  22nd,  1912,  the 
President,  Prof.  A.  Dendy,  D.Sc.,  F.R.S.,  in  the  chair,  the 
minutes  of  the  meeting  held  on  June  25th,  1912,  were  read  and 
confirmed. 

Messrs.  William  Elliott  and  Leabury  Edwardes  were  balloted 
for  and  duly  elected  members  of  the  Club. 

Seventy-three  members  and  live  visitors  were  present. 
Thirteen  proposals  for  membership  were  read  by  the  Hon. 
•Secretary. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks  of 
the  members  were  voted  to  the  donors. 

A  letter  addressed  to  the  President  by  Mr.  Charles  Peveril 
was  read,  intimating  that  the  late  Mr.  J.  M.  Allen,  F.R.M.S., 
had  bequeathed  to  the  Club  his  microscopes  and  apparatus 
belonging  thereto.  This  legacy  was  accepted  by  the  Committee  ; 
it  consists  of  two  microscopes  and  some  small  accessories. 

The  Librarian  announced  that  he  had  received  a  copy  of 
L.  L.  Clark's  "  Objects  for  the  Microscope  "  to  replace  a  copy 
missing  from  the  library,  also  that  Prof.  Minchin's  "  Intro- 
duction to  the  Study  of  the  Protozoa  "  had  been  presented  by 
the  author. 

A  communication  from  Mr.  J.  Rheinberg,  F.R.M.S.,  "  On 
Resolutions  Obtained  with  Dark-ground  Illumination  and  their 
Relation  to  the  Abbe  Theory,"  in  the  absence  of  the  author,  was 
taken  as  read. 

A  very  interesting  paper,  "  The  Foraminifera  in  their  Role 
as  World-Builders,"  by  Messrs.  Earland  and  Heron- Allen,  was 
read  by  Mr.  Earland,  and  illustrated  by  a  large  number  of 
.pictures  of  the  various  forms  described,  which  were  shown  upon 


104  PROCEEDINGS    OF   THE 

a  screen   by   Mr.   Ogilvy  by  means  of  the  Epidiascope,  and  by 
specimens  of  the  deposits  placed  upon  the  table. 

The  President  said  it  was  hardly  necessary  to  ask  them  to- 
give  a  hearty  vote  of  thanks  to  Mr.  Earland  for  reading  them 
such  an  interesting  paper.  A  vote  of  thanks  was  carried  by 
acclamation. 

Through  the  kindness  of  Messrs.  Leitz's  London  representative, 
Mr.  Ogilvy,  the  lecture  was  very  efficiently  illustrated  by  the 
use  of  the  Leitz  universal  projection  apparatus,  which  projected 
on  the  screen  ordinary  lantern -slides,  plates  and  illustrations 
from  books,  etc.,  single  photographs,  microscopic  sections  at 
varying  magnifications,  rock  hand-specimens  and  fossils.  The 
capabilities  of  the  apparatus,  which  employs  an  automatic  L-arc,. 
taking  30  amp.  at  about  60  volts,  were  further  demonstrated  by 
Mr.  Ogilvy  and  his  assistants  after  the  meeting.  The  approxi- 
mate candle-power  produced  is  about  10,000.  Micro-projection 
may  be  accomplished  in  the  usual  horizontal  position,  and,  for 
hanging  drop  slides  or  other  living  preparations,  a  vertical 
position  is  also  possible.  Besides  the  projection  of  lantern-slides 
of  any  size  up  to  12  cm.  square  (4|in.),  for  which  a  novel  and 
exceedingly  efficient  holder  is  provided,  it  is  also  possible  to 
project  larger  transparencies  up  to  20  cm.  square  (8  in.),  or  such 
preparations  as  brain  sections,  etc. 

The  President  said  they  were  all  very  much  indebted  to  Mr. 
Ogilvy  for  what  he  had  shown  them ;  he  had  himself  been 
greatly  interested  to  see  how  perfectly  the  Epidiascope  was 
adapted  for  showing  drawings,  lantern-slides  and  microscopic 
specimens  on  the  screen  in  a  manner  which  he  had  not  previously 
been  aware  of. 

The  Hon.  Secretary  regretted  to  have  to  announce  the  recent 
death  of  Dr.  M.  C.  Cooke,  M.A.,  LL.D.,  A.L.S.,  one  of  t he- 
original  founders  of  the  Club,  and  President  1882-3. 


At  the  meeting  of  the  Club  held  on  November  26th,  1912,  the 
President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair,  the 
minutes  of  the  meeting  held  on  October  22nd  were  read  and 
confirmed. 

Messrs.  E.  Pitt,  G.  C.  Bellamy,  T.  Tonkin,  H.  Pulford,. 
E.  H.   Bassett,   L.  C.  Hayward,  William  Hill,   D.   A.  Mardonr 


QUEKETT    MICROSCOPICAL    CLUB.  105 

P.  E.  Dollin,  F.  Whitteron,  J.  M.  Coon,  E.  W.  H.  Row  and 
W.  Hardinan  were  balloted  for  and  duly  elected  members  of 
the  Club. 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks  of 
the  members  were  voted  to  the  donors. 

The  President  said  that  members  would  be  very  glad  to  hear 
that  the  announcement  made  at  their  last  meeting,  of  Dr.  Cooke's 
death,  was  incorrect.  They  had  it  apparently  on  the  best 
authority,  and  the  scientific  Press  generally  had  been  similarly 
misinformed.  lie  was  sure  that  all  members  would  hope  that 
Dr.  Cooke  would  long  remain  a  member  of  the  Club. 

The  President  asked  members  to  extend  a  hearty  welcome  to 
a  visitor,  Dr.  E.  P.  Hodges.  Dr.  Hodges  was  State  Medical 
Supervisor  for  Indiana,  U.S.A.,  had  been  for  many  years  a 
Fellow  of  the  Royal  Microscopical  Society,  and  took  the  greatest 
interest  in  microscopy  generally. 

Mr.  C.  Lees  dirties,  for  Messrs.  Baker,  exhibited  a  new 
one-sixteenth  oil-immersion  objective  of  N.A.  1*32.  It  was 
made  of  a  stable  glass — one  that  would  stand  any  climate.  Its 
qualities  were  appreciated  by  members,  who  admired  the 
excellent  definition  it  gave  (with  a  x  7  ocular)  on  a  fine  pre- 
paration of  Trypanosoma  gambiense. 

The  President  made  some  remarks  relating  to  a  new  species  of 
Holothurian.  He  said  he  had  no  formal  paper  to  read,  but  the 
subject  had  been  before  the  Club  a  few  months  ago  {Journ. 
Q.M.C.,  Ser.  2,  Vol.  XI.  p.  536),  when  an  Australian  visitor, 
Mr.  F.  Whitteron,  of  Geelong,  had  brought  for  distribution  a 
number  of  specimens  of  a  species  of  Holothurian  which  had  an 
interesting  history.  They  had  been  collected  in  Corio  Bay,  Port 
Phillip.  Continental  experts  had  identified  the  species  as  Trocho- 
dota  dunedinensis  (Parker).  That  identification,  however,  proved 
to  be  incorrect,  and,  as  specimens  had  been  distributed  at  their 
June  meeting,  he  thought  it  proper  to  bring  the  matter  before 
the  notice  of  the  Club.  On  examining  the  material  he  had  then 
taken,  he  found  that  all  the  calcareous  wheels  had  been  dis- 
solved, possibly  by  the  medium  in  which  they  were  preserved 
being,  or  becoming,  slightly  acid.  Fortunately,  this  failure  was 
not  of  importance,  as,  in  a  reprint  he  had  received  from  the 
Proceedings  of  the  Royal  Society  of  Victoria,  Mr.  E.  C.  Joshua, 
of    Melbourne,    discussed    the    species    found   at    Geelong,    and 


106  PROCEEDINGS    OF    THE 

definitely  showed  that  it  was  not  identical  with  the  New  Zealand 
form.     He  calls  the  Geelong  species  Taeniogyrus  Allani.      The 
President  referred  to  the  varying  nomenclature  of  these  species. 
He  considered  all  the  forms  closely  related,   and  preferred  the 
generic  name  Chiridota,  applied  by  Parker  to  the  New  Zealand 
form.      The  differences  between  the  New  Zealand  and  Geelong 
species  were  then  considered.     The  structure  of  the  wheel  spicule 
had  been  worked  out  by  Mr.  Joshua,  and  was  described  in  his 
paper.     The  President  had  worked  out  the  N.Z.  form  some  years 
ago,  and  described  and  sketched  on  the  blackboard  the  various 
stages  observed.     The  spicule  has  a  broad  margin,  corresponding 
to  the  rim  of  the  wheel.     Then  there  are  six  spokes  radiating 
from  the  centre,  and  in  some  species  there  is  a  small  hole  in  the 
middle.     Specimens  of  C.  dunedinensis  exhibit  a  uniform  minute 
toothing  all  round  the  margin,  which  is  inturned.      The  other 
side  of  the  wheel  has  a  different  appearance.     The  six  spokes 
show  as  before ;    but  the  toothed  edge  is  not  seen   at  the  top 
focus.      Further,   fresh    detail   is    exhibited   in    the   form    of   a 
six-rayed  cross,  which  stands  above  the  level  of  the  spokes.     A 
diagram  of  a  vertical  section  was  given.     The  President  said  it 
was  a  very  curious  and  wonderful  structure,  and  the  development 
was  of  extreme  interest.     Commencing  with  the  six-rayed  cross, 
a  thickening  appears  at  the  end  of  each  ray,  and  on  one  surface 
only.     This  was  the  earliest  stage  observed.     As  the  thickenings 
grow,   they  exert   pressure   on  each   other,  and   presently  each 
spoke  bifurcates  at  the  extremity.     The  bifurcated  ends   begin 
to  grow  outward,  and  presently  meet,  and,  fusing,  form  the  rim 
of  the  wheel.     The  rim  turns  in,  and  is  denticulated  all  round 
the   margin.     The   spicule   is,    of    course,    useful   as    a   skeletal 
structure  ;  but  it  is  not  at  all  apparent  why  such  a  remarkable 
and  elaborate  form  should  be  required.     The  chief  differences  in 
C  Allani,  as  compared  with   C.  dunedinensis,  are  :  The  margin, 
instead  of  rounding  off,  remains  hexagonal.      The   face  showing 
the  six-rayed  cross  is  much  the  same,  excepting  that  it  also  is 
hexagonal ;    but    the   toothed    rim    is    not  uniform,  but    follows 
a  curve  with  little  bays  opposite  the  angles  of  the  hexagon,  and 
the  toothing  is  pronounced  in  parts,  but  is  absent  from  the  bays 
or  notches.     It  is  very  difficult  to  account  in  any  way  for  such 
minute  differences  as  those    noted.      The   new   form,   which    he 
would  prefer  to  call  Chiridota  Allani,  was  first  found  by  Mr. 


QUEKETT   MICROSCOPICAL    CLUB.  107 

J.  M.  Allan,  near  Geelong,  and  subsequently  by  Mr.  E.  C. 
Joshua. 

Replying  to  a  question,  the  President  said  that  formalin  was 
very  unsafe  to  use  in  such  cases,  as  it  frequently  becomes  acid 
after  a  short  time. 

Mr.  J.  Burton  said  he  took  some  of  the  material  brought  by 
Mr.  Whitteron,  and,  after  some  trouble,  had  found  some 
wheels  in  the  skin.  They  looked  as  though  acid  had  been 
previously  applied.  The  wheels  showed  a  tendency  to  break 
down  into  anchors,  reminding  one  of  the  well-known  Synapta 
spicules.  The  anchor  form,  as  the  President  had  said,  was  an 
early  stage  in  the  development  of  the  wheel.  The  wheels,  under 
a,  binocular,  proved  to  be  basin-shaped.  There  was  a  second 
kind  of  spicule,  something  like  a  drawer- handle  in  shape,  and  a 
third  shape,  found  only  in  the  tentacles,  where  it  was  very 
numerous,  constituting,  perhaps,  50  per  cent,  of  their  bulk. 

The  thanks  of  the  meeting  were  unanimously  voted  to  the 
President  for  his  communication. 

Several  notes  from  Mr.  E.  M.  Nelson  were  read  to  the  meeting 
by  the  Hon.  Secretary,  as  under  : 

1.  "On  Microscopic  Construction  and  the  Side-Screw  Fine 
Adjustment,"  in  which  he  traced  the  history  of  this  form  from 
1841  to  the  present  time,  with  some  suggestions  of  his  own  for 
further  improvement. 

2.  On  the  Navicula  used  as  a  test  by  the  Jurors  of  the  1862 
Exhibition,  which  he  thought  was  the  "  English "  rhomboides 
under  the  name  of  Xavicula  affinis. 

3.  "  On  a  New  Low-power  Condenser  :'  for  use  with  objectives 
as  low  as  4  in.,  the  ordinary  condenser  not  filling  the  field  with 
light  when  low  powers  were  used. 

The  way  this  difficulty  may  be  surmounted  is  to  construct 
the  condenser  upon  the  telephoto  principle.  This  has  now  been 
done,  and  Messrs.  Baker  exhibited  to  the  meeting  a  substage 
condenser,  made  from  Mr.  Nelson's  design,  which  has  4  in.  of 
focal  length,  and  requires  only  1  in.  of  working  distance.  With 
this  condenser  the  image  of  the  flat  of  the  flame  bears  the  same 
relation  to  a  4-in.  objective  with  the  large  field  of  a  P.  and  L. 
No.  1,  A  eyepiece,  as  the  image  with  one  of  the  ordinary  uni- 
versal condensers  with  the  top  off  does  to  a  twro-thirds  ;  and 
this  is  precisely  what  was  wanted. 


108  PROCEEDINGS    OF   THE 

The  thanks  of  the  Club  were  voted   to   Mr.  Nelson  for  his 
communications. 


At  the  meeting  of  the  Club  held  on  January  28th  the 
President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair,  the 
minutes  of  the  meeting  held  on  November  26th,  1912,  were 
read  and  confirmed. 

Messrs.  Hilary  Mavor,  Robert  Spry,  E.  J.  Sheppard,  F.R.M.S.,. 
A.  C.  Coles,  M.D.,  D.Sc.,  A.  M.  Allison  and  H.  W.  Freeland 
were  balloted  for  and  duly  elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks 
of  the  members  voted  to  the  donors. 

Mr.  Watson  Baker,  for  Messrs.  Watson  &  Sons,  Ltd.,  ex- 
hibited and  described  a  new  model  microscope  which  had  a 
specially  long  horizontal  travel,  If  in.,  to  the  mechanical  stage, 
both  movements  working  on  the  same  axis.  The  fine  adjustment 
is  a  vertical  lever  actuated  by  the  now  customary  side-screw, 
and  permitting  the  worker  to  always  know  whether  the  body 
is  ascending  or  descending.  It  has  a  specially  long  range  of  coarse 
adjustment.  The  most  important  novelty  on  the  stand  was  a 
new  objective  changer,  made  on  the  principle  of  a  3-jaw  chuck  ; 
less  than  a  quarter-turn  of  a  collar  is  all  that  is  necessary  to 
engage  or  release  an  objective,  and  it  does  not  increase  the  tube 
length.  An  auxiliary  stage  was  also  shown.  This,  fitted  to  the 
usual  stage,  will  give  nearly  four  inches  of  horizontal  travel, 
and  should  be  found  very  useful  in  working  with  large  pre- 
parations. 

Mr.  A.  A.  C.  Eliot  Merlin,  F.R.M.S.,  sent  a  photomicrograph 
taken  at  x  320  of  Coscinodiscus  heliozoides,  showing  extended 
"  pseudopodia,"  from  a  preparation  by  Mr.  J.  D.  Siddall. 

The  fine  radiating  "  pseudopodia  "  can  be  well  seen  when  the 
print  is  examined  in  a  good  light  with  a  Verant  or  other  suitable 
hand  magnifier.  The  photograph  gives  the  impression  that  the 
radiating  filaments  are  real  appendages  of  the  organism,  and 
the  general  appearance  of  these  reminds  one  strongly  of  the 
pseudopodia  of  Discorbina  globidaris  as  figured  in  Carpenter 
(1901  edition),  page  798. 

The  photograph  as  a  whole  strikes  one  as  more  curious  than 
beautiful.  It  will,  however,  be  noticed  with  a  lens  that  several 
of   the  radiating    filaments  are  very    fine  and   in   exact   focus. 


QUEKETT    MICROSCOPICAL    CLUB.  109 

The  best  focal  plane  for  the  "  pseudopodia "  does  not  coincide 
■with  that  for  the  diatom  itself,  and  this,  together  with  the 
prolonged  exposure  necessary  to  bring  out  the  faintly  illuminated 
filaments,  causes  the  valve  to  be  much  over-exposed,  making 
the  diatom  appear  as  a  mare  blurred,  globular  white  patch  in 
the  print. 

The  President  gave  a  resume  of  a  communication  of  some 
length  by  Mr.  W.  M.  Bale,  F.H.M.S.,  of  Victoria,  Australia, 
entitled  "  Notes  on  Some  of  the  Discoid  Diatoms."  This  paper 
was  a  survey  of  some  of  the  principal  characters  which  have 
been  utilised  in  the  discrimination  of  species  in  three  or  four 
of  the  best-known  genera  of  discoid  diatoms.  Some  of  the 
conclusions  arrived  at  as  to  the  inadequacy  of  many  of  these 
distinctions  have  been  reached  by  previous  observers,  more 
especially  in  the  genus  Coscinodiscus ;  but  it  was  thought  that 
in  such  cases  the  special  instances  now  brought  forward  might 
be  serviceable  in  reinforcing  those  conclusions.  In  other  cases, 
particularly  in  the  genus  Actinoptychus,  the  author's  observa- 
tions tended  to  prove  that  characters  accepted  as  specific  even 
by  recent  authors  were  demonstrably  unreliable.  The  genera 
dealt  with  included  Coscinodiscus,  Actinocyclus,  Asteromphalus 
and  Actinoptychus. 

The  thanks  of  the  meeting  were  unanimously  voted  to  the 
President  for  communicating  this  important  paper. 

A  paper  on  "  British  Freshwater  Bhabdocoelida  (Planarians), 
a  Group  of  Turbellaria,"  by  H.  Whitehead,  B.Sc,  in  the  absence 
of  the  author  was  read  by  Mr.  J.  Wilson. 

After  some  discussion,  in  which  Messrs.  Scourfield  and  Ham- 
mond took  part,  the  President  said  that  the  Bhabdocoelids  were 
very  low  down  in  the  scale,  some  of  them  ranking  among  the 
lowest  of  multicellular  organisms.  Most  of  his  own  work  in 
Australasia  had  been  done  on  land  forms,  but  there  were,  pos- 
sibly, water  forms  as  well.  There  were  in  Australia  an  enormous 
number  of  land  Planarians  which  lived  under  stones,  rocks,  logs, 
etc.,  and  only  came  out  at  night.  Some  were  very  large,  reach- 
ing a  length  of  one  foot.  They  are  locally  incorrectly  termed 
"  land-leeches."  Many  are  brightly  coloured  in  stripes,  spots, 
and  patches  of  brilliant  blue,  red,  yellow,  orange,  and  sometimes 
iridescent.  These  colourations  were  very  useful  in  assisting 
naturalists  to  identify  species.     He  had  described  some  forty  new 


110  PROCEEDINGS    OF    THE 

species  from  Australia  and  New  Zealand,  and  was  very  glad  to 
see  that  the  study  of  the  group  was  being  taken  up  in  this- 
country. 

The  Hon.  Secretary  read  a  "  Note  on  Pleurosigma  angalaturu" 
by  Mr.  E.  M.  Nelson,  F.R.M.S.,  also  a  note  on  a  coloured  coma 
observed  in  examining  A.  Ralfsii,  by  the  same  author. 

Mr.  C.  F.  Rousselet,  F.R.M.S.,  read  a  paper  on  "The  Rotifera 
of  Devils  Lake,  and  description  of  a  new  Brachionus." 


At  the  meeting  of  the  Club  held  on  February  25th,  the  Presi- 
dent, Prof.  A.  Dend}r,  D.Sc,  F.R.S.,  in  the  chair,  the  minuter 
of  the  meeting  held  on  January  28th  were  read  and  confirmed. 
There  were  present  ninety -three  members  and  fourteen  visitors. 

Messrs.  H.  T.  Laurence,  F.  W.  Mills,  J.  W.  Durrad,  W.  Oatley, 
E.  A.  Anstey,  C.  D.  Hutchin,  A.  Booker,  F.  W.  Parrott,  J.  J. 
Armitage,  N.  Burns,  J.  Snell,  A.  0.  Trotman,  R.  A.  Taylor, 
J.  Bancroft,  J.  E.  Barnard,  R.  Hall,  V.  Tyas  and  Dr.  J.  C. 
Kaufmann  were  balloted  for  and  duly  elected  members  of  the 
Club. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks  of 
the  members  voted  to  the  donors. 

The  President  having  appointed  Messrs.  Fuller  and  Watson - 
Baker,  jun.,  as  Scrutineers,  the  ballot  for  Officers  and  Council 
was  proceeded  with. 

The  Hon.  Secretary  (Mr.  \V.  B.  Stokes)  read  the  Committee's 
forty-seventh  Annual  Report.  It  was  considered  that  the  past 
year  was  one  of  marked  progress.  Forty  new  members  had  been 
elected;  five  members  had  died  and  fifteen  had  resigned  during 
the  past  year.  The  total  membership  on  December  31st,  1912, 
was  406. 

The  Hon.  Treasurer  (Mr.  F.  J.  Perks)  presented  the  Annual 
Statement  of  Accounts  and  the  Balance-sheet  for  1912,  which 
had  been  duly  audited  and  found  correct. 

The  Report  and  Balance-sheet  were  received  and  adopted,  on 
the  motion  of  Mr.  Morland,  seconded  by  Mr.  Gaff. 

The  President,  having  asked  Prof.  E.  A.  Minchin  to  take  the 
chair,  delivered  his  Annual  Address,  taking  as  his  subject  "  By- 
products of  Organic  Evolution." 

Prof.  Minchin  said  he  was  sure  all  present  would  agree  that 


QUEKETT    MICROSCOPICAL   CLUB.  Ill 

they  had  listened  to  a  very  fascinating  address  from  one  who 
was  the  foremost  living  authority  in  Europe  on  sponge  spicules. 
The  Club  was  very  fortunate  in  having  the  subject  dealt  with  by 
him.  The  objects  were  quite  well  known  to  all  microscopists,  and 
he  believed  he  was  right  in  saying  that  all  the  different  forms  of 
spicules  described  could  be  obtained  from  sponges  found  on  our 
own  coasts.  He  had  great  pleasure  in  moving  a  hearty  vote  of 
thanks  to  their  President  for  his  address,  and  in  asking  him  to 
allow  it  to  be  published  in  the  Journal. 

The  motion  having  been  put  to  the  meeting,  was  carried  by 
acclamation. 

The  President,  in  acceding  to  this  request,  thanked  the  mem- 
bers for  the  way  they  had  received  the  address,  but  said  he  had 
thought  himself  that  Prof.  Minchin  was  the  greatest  authority 
they  had  on  these  microscopic  objects. 

A  vote  of  thanks  to  the  Auditors  and  Scrutineers,  having  been 
moved  by  Mr.  W.  R.  Traviss  and  seconded  by  Mr.  A.  M.  Jones, 
was  put  to  the  meeting  and  carried  unanimously. 

Mr.  Bremner  then  moved  that  their  best  thanks  be  given 
to  the  officers  of  the  Club  for  their  services  during  the  year. 
They  had  given  them  a  very  valuable  amount  of  time  with  a 
most  excellent  result.  Mr.  Stokes  had  referred  to  the  work 
done  by  their  Librarian,  which  must  have  occupied  hundreds 
of  hours,  and  as  for  Mr.  Stokes  himself  his  unfailing  courtesy 
and  his  capacity  for  hard  work  were  deserving  of  their  highest 
appreciation. 

Mr.  A.  D.  Michael  said  he  always  felt  very  strongly  that 
the  great  success  which  attended  the  scientific  societies  of  London 
was  mainly  due  to  the  work  done  by  their  officers.  He  had 
much  pleasure  in  seconding  the  vote  of  thanks  to  those  who  had 
so  ably  conducted  the  business  of  the  Club  during  the  year. 

Mr.  W.  B.  Stokes  said  that  as  this  was  the  last  occasion  on 
which  he  would  be  able  to  speak  as  an  officer  of  the  Club  he 
would  reply  for  his  colleagues ;  he  thanked  the  members  for 
the  vote  they  had  just  carried.  He  felt  he  was  leaving  the 
Secretaryship  in  better  hands  than  his  own  ;  but  was  very  glad 
that  he  was  leaving  it  not  when  the  Club  was  at  the  bottom 
of  a  curve  of  prosperity,  but  very  nearly  at  the  top.  He  thanked 
the  officers  for  the  ready  assistance  which  they  had  always  given 
him,  and  which  had  rendered  his  duty  a  pleasant  one,  and  he 


112         PROCEEDINGS    OF    THE    QUEKETT    MICROSCOPICAL    CLUB. 


desired  also  to  thank  the  members  for  the  kind  way  in  which 
they  had  supported  him  during  his  term  of  office  as  their 
Secretary. 

The  President  announced  the  result  of  the  ballot  for  Officers 
and  Committee  to  be  as  follows  : — 


President 


Vice-Presidents 


Treasurer     . 
Secretary 

Assistant  Secretary 
Foreign  Secretary 
Reporter  .... 
Librarian     . 
Curator  .... 
Editor     .... 


Vice  four  senior 
Members  retired. 

Vice  James  Burton 
{apptd.  Secretary.) 


Prof.    Arthur    Dendy,    D.Sc,    F.R.S., 
F.L.S. 

C.  F.  Rousselet,  F.R.M.S. 

E.  J.  Spitta,  L.R.C.P.,  M.R.C.S.,F.R.A.S. 

D.  J.  Scourfield,  F.Z.S.,  F.R.M.S. 
.Prof.  E.  A.  Minchin,  M.A.,  F.R.S. 

Frederick  J.  Perks. 
James  Burton. 
J.  H.  Pledge,  F.R.M.S/ 
C.  F.  Rousselet,  F.R.M.S. 
R.  T.  Lewis,  F.R.M.S. 
S.  C.  Akehurst. 
C.  J.  Sidwell,  F.R.M.S. 
A.  W.  Sheppard,  F.Z.S.,  F.R.M.S. 
R.  Paulson,  F.R.M.S. 
J.  Grundy. 

M.  Blood,  F.C.S.,  F.R.M.S. 
.0.  D.  Soar,  F.L.S.,  F.R.M.S. 
R.  Inwards,  F.R.A.S. 


11 


o 


FORTY-SEVENTH   ANNUAL   REPORT, 

Reviewing  the  work  of  the  Club  during  the  year  1912  shows 
that  it  has  been  a  period  in  which  its  high  value  to  the  user 
of  the  microscope  has  been  again  demonstrated.  Not  only  has 
the  Club  maintained  the  interest  of  its  meetings,  but  it  has 
exhibited  a  revival  of  interest  in  matters  connected  with  the 
instrument  itself.  There  has  been  a  very  good  attendance  at 
conversational  meetings,  and  the  favour  shown  to  the  excursions 
during  a  season  having  a  record  rainfall  is  well  worthy  of  note. 
The  number  of  new  members  added  during  the  twelve  months 
is  forty,  50  per  cent,  advance  on  that  of  1911,  and  this  number 
would  have  been  even  greater  if  an  ordinary  meeting  in  Decem- 
ber had  been  possible.  The  Club  has  lost  five  members  by 
death,  and  resignations  have  accounted  for  fifteen ;  this  leaves 
a  net  gain  of  twenty  members.  The  total  membership  on 
December  31st  was  406. 

The  following  communications    have   been   made  during   the 
year : — 

Jan.  James  Burton.     Notes  on  Algae  collected  in  1911. 

Feb.  Prof.  E.  A.   Minchin,  F..R.S.     Some  Speculations  with 

regard  to  the  Simplest  Forms  of  Living  Beings  and 
the  Origin  of  Life. 
March.     H.  Sidebottom.     Lagenae  of  the  South-west  Pacific. 
„  C.  F.  Rousselet,  F.R.M.S.     On  New  Species  of  Rotifera. 

,,  D.  Bryce.     On  New  Species  of  Callidina. 

„  A.    E.   Conrady,   F.R.A.S.     On   Resolving   Powers  ob- 

tainable with  Dark-Ground  Illumination. 
„  A.    A.    C.    Eliot    Merlin,    F.R.M.S.     On   the   Capped 

Secondaries  of  Navicula  Smithii. 
April.       John     Stevens,    F.R.M.S.       On     Notommata    glgantea 
(Glascott). 
„  Duncan  J.  Reid.     Illumination  in  Critical  Work. 

May.         E.  M.  Nelson,  F.R.M.S.     On  the  sculled  fseudopodia 
of  certain  Diatoms. 
Journ.  Q.  M.  C,  Series  II.— No.  72.  8 


114  FORTY-SEVENTH    ANNUAL    REPORT. 

May.         R.  T.  Lewis,  F.R.M.S.     Notes  on  Solpuga. 

,,  A.  E.  Oonrady,  F.R.A.S.     Some  Experiments  on  Alter- 

native Microscopical  Theories. 
June.        W.     B.     Stokes.       Resolutions    obtained    with    Dark- 
Ground    Illumination    and    their    Relation    to    the 
Spectrum  Theory. 
„  R.  W.  H.  Row.     On  a  Saw-fly. 

Oct.  Julius  Rheinberg,  F.R.M.S.     On  Resolutions  obtained 

with  Dark-Ground   Illumination  and  their  Relation 
to  the  Abbe  Theory. 
A.    Earland,    F.R.M.S.,    and    E.    Heron-Allen,    F.L.S. 
Foraminifera  as  World  Builders. 
Nov.  Prof.    Arthur    Dendy,  F.R.S.     On    a   New   Species  of 

Holothurian. 
E.  M.  Nelson,  F.R.M.S.     On  Microscope  Construction. 

On  Namcula  rhomboides. 


55 

M  55  5?  >5 

On  a  New  Low-Power  Con- 


55  55  5)  55 

denser. 


The  following  exhibits  were  made  : — 


Jan.  E.  M.  Nelson,  F.R.M.S.     Photomicrographs. 

,,  A.    Earland,    F.R.M.S.     Photomicrographs   of    Recent 

Foraminifera. 
„  W.  Watson  &  Sons,  Ltd.     Microscope  Tray. 

,,  Charles  Baker.     Nelson's  Dark-Ground  Illuminator. 

March.     T.  W.  Butcher,  F.R.M.S.     Photomicrographs  of  Nam- 
cula Smithii. 
„  Charles  Baker.     Nelson's  Oil  Immersion  Dark-Ground 

Illuminator. 
,,  Charles   Baker.      Nelson's    Improved    Chromatic   Con- 

denser. 
„  Charles   Baker.      Nelson's    Improved    Rousselet   Com- 

pressor. 
April.       C.  D.  Soar,  F.R.M.S.     Drawings  of  Water-Mites. 
„  A.  W.  Stokes.     Electric  Lamps  for  the  Microscope. 

„  C.    F.   Rousselet,    F.R.M.S.      Diatoms   with    "Pseudo- 

podia." 
„  Charles  Baker.     A  New  l|-in.  Objective  of  N.A,  0'18. 

Oct.  E.  Leitz.     The  Epidiascope. 


FORTY-SEVENTH  ANNUAL  REPORT.  115 

Nov.         Charles    Baker.     A   New    l/16th-inch   Oil   Immersion 
Objective. 
,,  Charles  Baker.     Nelson's  New  Low-Power  Condenser. 

Your  Committee  wish  to  thank  the  authors  and  exhibitors 
for  these  interesting  communications  and  exhibits.  It  will  be 
seen  that  there  has  been  no  falling-off  in  either  the  quality  or 
quantity  of  papers  submitted  to  the  Club. 

There  were  eleven  excursions  during  the  season,  and  all  were 
well  attended,  except  on  one  occasion  when  the  weather  was 
very  bad ;  the  record  number  of  fifty-three  members  met  to  visit 
the  Royal  Botanic  Gardens.  The  total  attendances  for  all  ex- 
cursions was  235,  which  is  also  a  record  for  any  one  year,  and  the 
average  of  21*4  per  excursion  has  only  been  exceeded  once  before. 

The  collecting,  though  not  including  anything  new,  was  always 
satisfactory. 

The  thanks  of  the  Club  are  due  to  the  Secretary  of  the  Royal 
Botanic  Gardens  and  to  the  Metropolitan  Water  Board  for 
permission  to  visit  their  enclosures ;  also  to  the  Port  of  London 
Authority  and  Mr.  Carlyle,  who  so  kindly  entertained  the 
members  at  tea  after  their  visit  to  the  Surrey  Commercial  Docks. 
Later  in  the  year  a  party  of  members  gave  an  exhibition  of 
Pond  Life  at  the  Dock  Club  and  Institute,  on  which  occasion 
Messrs.  Soar,  Offord  and  Wilson  gave  short  lectures  with  lantern 
illustrations. 

The  Hon.  Librarian  and  his  assistant  have  expended  a  con- 
siderable amount  of  time  and  labour  upon  the  classification  and 
arrangement  of  the  Club's  books,  and  great  progress  has  been 
made  with  the  preparation  of  the  new  catalogue.  The  amount 
allotted  to  the  cost  of  binding  has  been  exceeded  by  £5,  and 
repairs  and  cases  for  loose  parts  have  cost  about  <£11.  The 
question  of  the  elimination  of  periodicals  containing  nothing  of 
particular  interest  to  microscopists  is  before  your  Committee ; 
the  limitation  of  space  for  housing  the  Club's  books  being  a 
difficulty  that  it  has  to  meet.  The  Library  has  been  used  in 
1912  as  much  as  in  previous  years,  but  the  cost  of  housing 
relatively  to  the  use  that  is  made  of  the  books  presents  quite 
a  serious  problem  for  consideration  by  your  Committee. 

During  the  year  under  review  the  following  volumes  have  been 
added : — 


116  FORTY-SEVENTH    ANNUAL    REPORT. 

LIST   OF   BOOKS   PURCHASED    SINCE    APRIL    1912. 

SlJSSWASSERFAUNA    DEUTSCHLANDS  : 

Part      II.     Copepoda,  Ostracoda,  Malacostraca. 
,,    XIV.     Rotatoria  and  Gastrotricha. 

Science  of  the  Sea.     Edited  by  G.  H.  Fowler.     Issued  by  the 
Challenger  Society. 

Huyghen's  Treatise  on  Light.     Translated  by  Prof.  Silvanus  P. 
Thompson. 

Also  fifty  copies  of  Henry  Sidebottcm's  paper,  "  Lagenae  of 

the    South-West   Pacific    Ocean,"   reprinted    from  the    Q.  M.  C. 

Journal,  April  1912,  Vol.  XI.     These  copies  may  be  purchased 
at  2s.  Qd.  each. 

LIST   OF    BOOKS   PRESENTED    SINCE   APRIL    1912. 

Presented  by  the  Author,  E.  Penard  : 
Notes  sur  quelques  Sarcodines.     Part  I. 

Presented  by  ft.  T.  Lewis  : 
Objects  for  the  Microscope.     2nd  Ed.  .         .     L.  Lane  Clark. 

Presented  by  Julius  Rheinberg  : 
Spectrum  Method  of  Colour  Photography. 

Presented  by  the  Author,  Prof.  E.  A.  Minchin  : 
Introduction  to  Study  of  Protozoa. 

Presented  by  James  Motham  : 
List  of  the  Fossil  Radiolaria  from  Barbados.    A.  Earland. 

Figured  in  Ehrenberg's  Fortsetzung. 
Radiolaria       .......     A.  Earland. 

Reprinted  from  the  Q.  M.  C.  Journal,  April  1900. 

Presented  by  Mrs.  D.  Wesche  : 

Phylogeny  of  the  Nemocera  .         .         .     W.  Wesche. 

With  notes  on  the  leg  bristles,  hairs  and  certain  mouth  glands 
of  Diptera. 


FORTY-SEVENTH    ANNUAL    REPORT.  117 

Presented  by  the  Author,  E.  Penard  : 
Notes  sur  quelques  Sarcodines.     Part  II.,  1906. 

Presented  by  the  Author,  Dr.  J.  B.  De-Toni  : 

Sylloge  Algarum  : 

Vol.       T.  Sections  I.  and  II.  Chlorophyceae. 

,,       II.  Bacillarieae. 

,,     III.  Fucoideae. 

,,      IV.  Sections  I.,  II.,  III.,  IV.,  Florideae. 

,,        V.  Myxoph}-ceae. 

Presented  by  the  Author,  C.  E.  Heath  : 
Beginners'  Guide  to  the  Microscope. 

During    the    year    ending    December    1912    the    Library    has 
received  the  following  publications : 

Quarterly  Journal  of  Microscopical  Science. 

Victorian  Naturalist. 

Mikrokosmos. 

Royal  Microscopical  Society. 

British  Association. 

Royal  Institution. 

Geologists'1  A  ssociation. 

Manchester  Literary  and  Philosophical  Society. 

Hertfordshire  Natural  History  Society. 

Bristol  Naturalists'  Society. 

Birmingham  Natural  History  and  Philosophical  Society. 

Botanical  Society  of  Edinburgh. 

Glasgow  Naturalists  Society. 

Croydon  Natural  History  Society. 

Indian  Museum  (Calcutta). 

Royal  Society  of  New  South  Wales. 

American  Microscopical  Society. 

Sin ithsonian  Instit ution. 

Academy  of  Natural  Science,  Philadelphia. 

Missouri  Botanic  Garden. 

Philippine  Journal  of  Science. 

Bergen  Museum. 

Lloyd  Library,  Cincinnati. 


118  FORTY-SEVENTH  ANNUAL  REPORT. 

U.S.  National  Herbarium. 

Royal  Society.     Series  B. 

Natural  History  Society  of  Glasgoiv. 

Zoologisch-botanischen  Gesellschaft,  Wien. 

Redia. 

U.S.  National  Museum. 

Nuova  Notarisia. 

Nyt  Magazin. 

Birmingham  and  Midland  Institute  and  Scientific  Society. 

Liverpool  Microscopical  Society. 

Nova  Scotian  Institute  of  Sciences. 

Royal  Dublin  Society. 

Canadian  Institute. 

University  of  California. 

Tijdschrift. 

Illinois  State  Laboratory  of  Natural  History. 

Scottish  Microscopical  Society. 

The  Club's  collection  of  slides  has  been  increased  by  133 
preparations,  including  a  further  donation  of  fifty  Freshwater 
Rhizopods  from  Dr.  Penard.  An  interesting  donation  consisted 
of  several  fine  injected  anatomical  preparations  mounted  by  the 
late  Sir  Benjamin  W.  Richardson  over  fifty  years  ago,  which  are 
still  in  perfect  condition.  It  is  proposed  to  publish  in  future 
issues  of  the  Journal  lists  of  additions  to  the  Cabinet,  and  these 
lists  will  serve  as  a  supplementary  catalogue  of  slides ;  the  first 
list  was  published  in  the  November  issue.  Two  microscopes  with 
several  objectives  and  accessories  were  bequeathed  to  the  Club 
by  the  late  J.  Mason  Allen,  so  that  the  Club  is  now  well 
provided  with  microscopes  for  exhibiting  objects  at  the  meetings. 

The  thanks  of  the  Club  are  due  as  in  former  years  to  the 
editors  of  the  English  Mechanic  and  Knowledge  for  publishing 
excellent  reports  of  the  ordinary  meetings.  Those  in  the  former 
journal  are  of  great  use  in  keeping  country  members  au  courant 
with  the  doings  of  the  Club. 

Your  Committee  desires  to  thank  the  officers  for  their  services 
during  the  past  year,  and  desires  to  call  attention  to  the 
following  resolution  which  was  passed  by  them  at  their  meeting 
on  January  28th  : — 

"  That  the  Committee  accept  with  grtat  regret  the  resignation 


FORTY-SEVENTH    ANNUAL    REPORT.  119 

of  Mr.  W.  B.  Stokes  as  Secretary  of  the  Club,  and  in  so  doing 
desire  to  express  their  hearty  thanks  to  Mr.  Stokes  for  his 
valuable  services." 

Your  Committee  sees  nothing  to  prevent  the  Club  maintaining 
its  traditional  usefulness.  There  is  no  question  as  to  the  need 
of  such  an  institution ;  but  there  is  need  to  remind  members 
of  the  importance  of  the  Club  being  all  it  seems  to  be  to  the 
new-comer,  and  not  a  cause  of  disappointment.  The  latter 
condition  need  never  obtain  if  the  dual  role  of  the  Club  be 
maintained,  presenting  an  effective  means  of  publicity  for  the 
specialist  and  a  help  to  the  less  experienced  amateur. 


120 


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121 


ON  SOME  FORAMINIFERA  FROM  THE  NORTH  SEA 
DREDGED  BY  THE  FISHERIES  CRUISER  "HUX- 
LEY" (INTERNATIONAL  NORTH  SEA  INVESTIGA- 
TIONS—ENGLAND). 

By  Edward  Heron-Allen,  F.L.S.,  F.G.S.,  F.R.M.S.,  and 
Arthur  Earland,  F.R.M.S. 

{Head  March  25th,  1913.) 

Plates  10,  11. 

In  connexion  with  our  paper  on  the  distribution  of  Psammo- 
sphaera  and  Saccammina  in  the  Northern  Area  of  the  North 
Sea,*  Mr.  J.  0.  Borley,  M.A.,  of  the  Fisheries  Department, 
Board  of  Agriculture  (England),  suggested  a  continuation  of  our 
investigations  into  the  Southern  Area.  With  some  reluctance  we 
undertook  the  work,  having  little  expectation  of  any  tangible 
results,  as  Mr.  Borley  had  already,  from  his  personal  experience 
of  dredging  in  these  waters,  confirmed  the  generally  held  belief 
that  rhizopodal  life  was  of  very  sparing  occurrence  in  the  area 
in  question.  The  shallowness  of  the  sea  and  the  consequently 
excessive  wave  action  in  this  area  were  thought  to  be  factors 
limiting  the  development  of  rhizopodal  life,  as  compared  with 
the  conditions  in  the  Scottish  North  Sea,  where  the  average  depth 
is  greater  and  the  disturbance  due  to  the  action  of  waves  and 
currents  is  consequently  less. 

By  the  courtesy  of  the  officers  of  the  Board  the  dredgings 
made  by  the  Fisheries  Cruiser  "  Huxley  "  were  placed  at  our  dis- 
posal, and,  guided  by  the  admirable  charts  plotted  by  Mr.  Borley 
to  show  the  distribution  of  "  silt  areas "  in  the  North  Sea,  six 

J 

*  "On  some  Foraminifera  from  the   North  Sea,  etc.,  dredged  by  the 

Fisheries  Cruiser  "  Goldseeker  "  (International  North  Sea  Investigations — 
Scotland).     II.  On  the  distribution  of  Saccammina  sphaerica  (M.  Sars)  and 
Psa)iimos])haera  fusca  (Schulze)  in  the  North  Sea."     Journ.  R.  Micr.  Soc. 
1913,  pp.  K26,  pis.  i.-iv. 

Journ.  Q.  M.  C,  Series  II. — No.  73.  9 


122     E.    HERON- ALLEN    AND    A.    EARLAND    ON    SOME    FORAMINIFERA 

dredgings  were  selected,  three  from  the  most  northerly  area 
dredged  by  the  "  Huxley"  and  three  from  an  area  considerably 
farther  south. 

The  three  Northerly  Stations  selected  lie  far  to  the  N.E.  of 
the  Dogger  Bank,  in  the  centre  of  the  North  Sea,  and  in  what 
is,  strictly  speaking,  the  Scottish  area  of  that  sea.  They  lie  in 
the  neighbourhood  of  the  Great  Fisher  Bank,  and  are  contiguous 
to  the  most  southerly  line  of  "  Goldseeker"  Stations  (Stns.  41°, 
41B,  41A,  42,  etc.)  but  farther  out  to  sea  towards  the  east.  These 
three  stations  are  referred  to  in  the  following  paper  as  the 
Northern  or  Outer  Area. 

The  three  Southern  Stations  selected  lie  in  the  deep  trough  of 
water  between  the  Dogger  Bank  and  the  Northumbrian  coast, 
and  are  quite  close  to  the  shore.  They  are  referred  to  in  the 
paper  as  the  Southern  or  Inner  Area. 

These  dredgings  were  carefully  selected  with  the  view  of  obtain- 
ing the  muddiest  deposits  possible,  such  conditions  being  most 
favourable  for  rhizopodal  life ;  and  they  probably  represent  the 
richest  of  the  "  Huxley "  dredgings,  all  the  others  which  were 
cursorily  examined  consisting  of  clean  siliceous  sand  with  hardly 
any  trace  of  microzoa.  Such  deposits,  Mr.  Borley  assures  us,  are 
typical  of  the  greater  part  of  the  Southern  North  Sea. 

Owing  to  the  widely  separated  stations  selected  the  microfauna 
of  these  six  dredgings  may  probably  also  be  regarded  as  typical 
of  the  inshore  and  midsea  areas.  The  comparative  richness  of 
the  fauna  of  the  Southern  Area,  as  compared  with  the  Northern, 
is  undoubtedly  due  to  the  proximity  of  the  coastline  and  the 
abundant  food  supply  derived  from  the  coastal  deposits. 

All  the  dredgings  consisted  of  loose  sands  containing  a  con- 
siderable amount  of  mud ;  but  whereas  the  sands  from  the 
Northern  Area  were  easily  cleaned  (like  the  majority  of  the 
"Goldseeker"  dredgings  from  adjacent  stations),  the  sands  of 
the  Southern  Area  proved  somewhat  refractory.  They  con- 
tained numerous  pellets  of  hardened  mud  which  resisted  dis- 
integration, and  even  the  action  of  a  strong  solution  of  boiling 


FROM  THE  NORTH  SEA.  123 

soda  did  not  completely  remove  the  adherent  mud  from  the  sand- 
grains  and  foraminifera. 

This  is  a  noticeable  feature,  because  as  a  rule  muddy  dredgings 
are  readily  broken  down  if  thoroughly  dried  before  the  cleaning 
process  is  commenced,  and  even  the  most  stubborn  muds  generally 
succumb  to  the  action  of  boiling  soda. 

We  have,  however,  met  with  similarly  refractory  muds  at  a  few 
of  the  "  Goldseeker"  stations  in  the  Moray  Firth,  and  are  unable 
to  satisfy  ourselves  as  to  the  cause  of  this  viscosity,  which  is 
quite  possibly  due  to  different  causes  in  separate  localities. 
Among  the  various  explanations  which  have  occurred  to  us  are : 

1.  The  presence  of  the  Hag  (Myxine  glutinosa).  This  loath- 
some fish  is  very  common  at  some  of  the  "  Goldseeker  "  stations 
where  the  viscosity  has  been  observed,  and  as  when  captured 
or  touched  it  exudes  an  incredible  quantity  of  slime,  it  is  quite 
possible  that  the  presence  of  this  fish  in  any  numbers  might 
locally  influence  the  nature  of  the  sea-bottom.  But  Mr.  Borley 
tells  us  that  Myxine  is  rare  in  the  vicinity  of  the  Stations 
sampled,  so  it  may  be  dismissed  from  consideration  so  far  as  the 
"  Huxley  "  material  is  concerned. 

2.  Chemical  changes  in  the  mud  owing  to  its  having  passed 
through  the  digestive  organs  of  worms  and  Echinoderms,  many 
of  which  obtain  their  nutriment  by  swallowing  mud  and  extract- 
ing the  organic  matter.  Thus,  in  the  deep  water  of  some  of  the 
Norwegian  fjords,  the  bottom  deposit  consists  of  a  very  fine 
mud  full  of  the  tests  of  rhizopods  and  swarming  with  Annelids. 
When  the  mud  is  dried  and  broken  down  again  in  water,  and 
the  foraminifera  have  been  removed  by  floating  and  elutriation, 
a  mass  of  fine  granular  material  is  left  which  under  the  micro- 
scope proves  to  consist  of  small  oval  pellets  of  mud,  the  excreta 
of  worms  (PL  11,  fig.  2).*  These  pellets  resist  the  action  of 
soda,  making  it  evident  that  the  mud  must  have  become  altered, 

*  Such  deposits  are  presumably  similar  to  those  referred  to  by  Dr.  Johan 
Hjort  under  the  name  of  "coprolitic  muds."  See  The  Depths  of  the  Ocean, 
by  Dr.  J.  Hjort  and  Sir  John  Murray  (1912),  p.  148. 


124  E.  HERON- ALLEN  AND  A.  EARLAND  ON  SOME  FORAMINIFERA 

/ 

or  at  any  rate  that  the  separate  particles  must  have  become 
agglutinated  during  their  passage  through  the  alimentary  canals 
of  the  worms.  Annelid  remains  are  of  fairly  frequent  occurrence 
in  the  "Huxley"  dredgings  from  the  Southern  Area,  but  not 
noticeably  so. 

3.  It  is  a  matter  of  common  knowledge  that  fresh  mud  or 
clay,  if  dried,  breaks  down  readily  in  water ;  but  that,  if  it  is 
worked  or  "puddled"  before  being  dried,  it  becomes  plastic,  and 
then  resists  disintegration.  It  is  possible  that  wave  or  current 
action  might  thus  serve  to  cover  the  surface  of  sand-grains  and 
foraminifera  with  a  coating  of  mud  in  a  plastic  or  colloidal 
condition,  and  on  the  whole  we  are  inclined  to  favour  this 
explanation,  so  far  as  the  viscosity  of  the  "  Huxley"  deposits  is 
concerned. 

The  whole  question,  however,  though  interesting  from  the 
point  of  view  of  the  chemist  and  physicist,  lies  rather  outside 
the  province  of  the  zoologist,  although  it  seems  evident  that  the 
phenomenon  might  be  of  great  importance  from  the  geological 
point  of  view,  as  such  viscosity  would  favour  the  preservation  of 
the  encrusted  microzoa. 

A  very  noticeable  feature  in  the  "  Huxley  "  dredgings  is  the 
roundness  of  the  sand-grains  as  compared  with  those  of  "Goldseeker" 
dredgings  from  similar  deposits.  This  is  conclusive  evidence  that 
the  grains  have  travelled  a  great  distance,  or  have  been  sub- 
jected to  tidal  action  within  restricted  geographical  limits  for  a 
prolonged  period  in  comparatively  shallow  water.  The  phe- 
nomenon has  been  observed  in  connexion  with  the  Goodwin 
Sands.  The  scour  of  the  tides  and  currents  round  the  Dogger 
and  Great  Fisher  Banks  is  doubtless  the  cause  of  the  rotundity 
of  the  "  Huxley  "  sands,  the  individual  grains  of  which  are  often 
as  smooth  and  polished  as  the  Aeolian  sands  of  the  desert 
(PI.  11,  fig.  3).* 

*  Laboratory  experiments  have  proved  that  a  quartz  grain  -£$  in.  in 
diameter  requires  an  amount  of  abrasion  equal  to  that  acquired  in 
travelling-  a  distance  of  3,000  miles  in  water  before  it  becomes  rounded  to 
the  form  of  a  miniature  pebble.     (Daubree,  Geologw  Experimentale,  Paris, 


FROM  THE  NORTH  SEA.  125 

To  return  to  the  microscopical  investigation  of  the  "  Huxley  " 
material :  as  already  stated,  this  was  originally  undertaken  solely 
with  the  view  of  extending  our  study  of  the  distribution  of  two 
species,  viz.  Psammosphaera  fusca  (Schulze)  and  Saccammhut 
sphaerica  (M.  Sars),  and  the  results,  so  far  as  they  affect  those 
species,  have  already  been  published  in  our  paper  dealing  with 
these  forms.*  But  in  the  course  of  an  examination  of  the 
material  we  found  so  many  other  forms  that  we  determined  to 
make  a  systematic  list  of  the  species  recorded.  This  list,  which 
we  now  publish,  contains  no  less  than  133  species  or  varieties, 
many  of  which  have  not  been  recorded  previously  from  the  areas 
in  question. 

It  must  not  be  concluded,  from  the  occurrence  of  so  extended 
a  list,  that  the  material  was  rich  in  foraminifera.  So  far  from 
this  being  the  case,  the  majority  of  the  dredgings,  previous  to 
manipulation,  gave  little  or  no  striking  indication  of  organic 
remains  beyond  the  presence  of  a  few  shell- fragments,  spines  of 
Echinoderms,  annelid  tubes,  and  an  occasional  rhizopod.  The 
dredgings  quite  justified  in  superficial  appearance  the  opinion 
which  Mr.  Borley  and  other  zoologists  familiar  with  the  North 
Sea  had  formed,  viz.  that  it  was  practically  devoid  of  foraminifera. 
But  careful  and  repeated  elutriations  of  the  dredgings  resulted 
in  the  separation  of  small  quantities  of  light  material  at  each 
station,  and,  as  is  often  the  case,  these  minute  samples  yielded 
a  more  diverse  fauna  than  .is  often  found  in  richer  gatherings. 
Except  in  the  case  of  a  few  dominant  species,  however,  the 
number  of  actual  specimens  observed  was  very  small.  Even  in 
the  case  of  the  dominant  species  the  proportion  of  individuals 
observed  to  the  total  bulk  of  the  dredging  was  too  insignificant 
to  be  estimated.     The  relative  abundance  of   the  species  in  the 

1807,  p.  47,  and  Phillips,  Q.  J.  Geol.  Soc,  vol.  xxxvii.,  p.  21).  But  the 
dynamics  of  the  troubled  waters  of  the  North  Sea  are  probably  quite 
different  from  the  controlled  action  of  a  revolving  cylinder  in  a  laboratory 
experiment ! 

*  Journ.  R.  Micr.  Soc,  1913,  p.  25. 


126     E.    HERON-ALLEN    AND    A.    EARLAND    ON    SOME    FORAMINIFERA 

annexed  lists,  as  indicated  by  the  letters  C,  R,  VR,  etc.,  must 
be  understood  to  refer  to  their  abundance  as  inter-contrasted  with 
other  foraminifera,  and  not  to  their  frequency  in  the  whole  bulk 
of  the  dredging. 

A  noticeable  feature  in  the  dredgings  of  the  Southern  or  Inner 
Area  is  the  relative  frequency  of  specimens  of  fossil  foraminifera. 
They  are  principally  small  types  derived  from  cretaceous  strata 
and  such  as  are  commonly  found  in  shore  sands  and  shallow- 
water  dredgings  round  the  southern  coasts  of  England.  But  a 
few  larger  and  well-developed  fossil  specimens  of  Nodosaria  and 
Cristellaria  were  noted  in  Hauls  869  and  871,  which  are  not 
cretaceous.  These  are  perhaps  derived  from  the  Crag,  a  sub- 
marine outcrop  of  which  formation  is  believed  to  extend  across 
the  North  Sea  *  ;  but  they  are  not  all  deeply  stained  with  iron, 
as  is  usually  the  case  with  the  larger  foraminifera  of  the  Crag, 
and  may  be  derived  from  the  Gault. 

Only  one  fossil  was  recorded  from  the  Northern  Area,  viz. 
Spirolocidina  impressa  Terquem.  This  is  no  doubt  derived  from 
some  submerged  Tertiary  deposit.  It  may  be  noted  that  Tertiary 
foraminifera  have  been  dredged  by  the  "  Goldseeker  "  in  the  Moray 
Firth. 

The  fossils  recorded  are  : 

Spiroloculina  impressa  Tei quern,  Northern  Area,  one  specimen. 
Textularia  globulosa  Ehrenberg,  Southern  Area,  all  stations. 
Nodosaria  pauperata  d'Orbigny,  Southern  Area,  two  stations. 
Nodosaria  plebeia  Reuss,  Southern  Area,  one  station. 
Cristellaria  costata  Fichtel  and  Moll  sp.,  Southern  Area,  one 

specimen. 
Cristellaria  rotulata  Lamarck  sp.,  Southern  Area,  one  station. 
Globigerina  aequilateralis  Brady,  Southern  Area,  one  station. 
Globigerina  cretacea  d'Orbigny,  Southern  Area,  two  stations. 

*  The  appearance  of  many  shell  fragments  dredged  from  a  band  of  the 
sea  bed  stretching  roughly  from  the  Suffolk  ccast  to  the  Continent 
suggests  that  they  come  from  the  Crag.  These,  however,  are  iron-stained 
and  curiously  glazed  in  appearance  in  seme,  but  not  in  all  cases,  owing 
to  attritiop. 


FROM    THE    NORTH    SEA. 


•~>7 


127 


One  of  these  species,  viz.  Cristellaria  rotulata  Lamarck  sp.,  was 
also  recorded  as  a  recent  form. 

An  examination  of  the  list  of  species  at  the  different  stations 
reveals  several  noticeable  features.  Taking  the  three  stations  in 
the  Northern  Area  first,  it  will  be  seen  that  they  vary  greatly 
in  richness,  Haul  767  yielding  only  14  species,  as  against  26  in 
Haul  770  and  54  in  Haul  772.  Even  the  richest  haul  in  the 
Northern  Area  contrasts  badly  with  the  poorest  haul  in  the 
Southern  Area,  which  yielded  72  species,  the  other  Southern 
hauls  yielding  79  and  94  species  respectively. 

This  discrepancy  is  largely  explained  by  the  abundant  records 
of  the  Family  Lagenidae  in  the  Southern  Area.  The  figures  are 
very  striking,  fossils  being  disregarded : 


Northern  Area. 

Southern  Area 

Lagena     . 

8 

30 

Nodosaria 

— 

3 

Lingulina 

— 

1 

Margin  ulina 

— 

1 

Vaginulina 

— 

1 

Cristellaria 

— 

2 

Polymorphina  . 

2 

4 

Uvigerina 

2 

2 

Total 


12 


44 


The  abundance  of  Lagenidae  in  this  Area  off  the  Northumber- 
land coast  has  already  been  noted  by  Brady.*  But  in  the 
"  Huxley "  dredgings  only  the  genus  Lagena  is  noticeably 
abundant,  the  other  genera  of  the  family  not  being  well 
represented. 

The  other  families  exhibit  a  similar  discrepancy  in  the  lists  of 
species  recorded  from  the  two  Areas,  but  it  is  not  so  noticeable 
as  in  the  case  of  the  Lagenidae. 


*  Report  British  Association,  1862,  p.  122;  also  Trans.  Tyneside 
Naturalists  Field  Club,  1863,  vol  v.,  part  4,  p.  292;  Ibid.,  1864.  vol.  vi., 
part  2,  p.   194. 


128     E.    HERON-ALLEN    AND    A.    EARLAND    ON    SOME    FORAMINIFERA 

The  dominant  forms  in  the  two  Areas  are  as  follows  *  : 


Northern. 

8.  Miliolina seminulum Linne 
sp. 

21.  Reophax  sco?yiurus  Mont- 
fort. 

26. 


37. 

42. 
69. 
82. 
97. 

100. 

106. 
118. 

123. 

124. 
126. 

132. 


Verneuilina       polystropha 

Reuss  sp. 
Bulimina  fusiformis  W  ill . 


Polymorphina      compressa 

d'Orbigny. 
Polymorphina  sororia 

Reuss. 

Truncatulina  lobatula  W. 

&  J.  sp. 
Rotalia  Beccarii  Linne  sp. 

Nonionina  depressula  W. 

&  J.  sp. 
Polystomella     striatopunc- 

tata  F.  &  M.  sp. 


Southern. 

Miliolina  seminulum  Linne  sp. 
Reophax  scorpiurus  Montfort. 

Haplophragmiiim  p>se udosp  irale 

Will.  sp. 
Verneuilina  polystropha   Reuss 

sp. 
Bidimina  fusiformis  Will. 
Lagena  laevigata  Reuss  sp. 
Lagena  striata  d'Orbigny  sp. 


Globigerina  rubra  d'Orbigny. 
Truncatulina  lobatula  W.  &  J. 

sp. 
V  C  at  one  station  only. 
Rotalia  orbicularis  d'Orbigny. 
Nonionina  depressula  W.  &  J. 

sp. 
Polystomella   striatopunctata  F. 

&  M.  sp. 


Several  of  these  forms  are  more  abundant  in  one  Area  than  in 
the  other,  as  may  be  seen  by  reference  to  the  table. 

Some  of  the  discrepancies  in  the  above  comparative  list  can  be 
explained  by  what  we  know  of  the  distribution  of  the  species  in 
other  rhizopodal  faunas.  Thus  (26)  Haplophragmiiim  pseudo- 
spirale  Will.  sp.  (PI.  10,  fig.  2-4)  appears  to  be  confined  to  coastal 
deposits.  It  is  very  common  in  many  muddy  shallow-water 
dredgings  round  the  W.  coast  of  Ireland  and  Scotland  and  in 
the  Shetlands,  but  the  u  Goldseeker  "  records  in  the  North  Sea  are 


*  The  numbers  refer  to  the  tabular  list  at  the  end  of  the  paper. 


FROM    THE    NORTH    SEA.  129 

very  few  and  entirely  confined  to  coastal  gatherings.  It  does  not 
occur  in  any  of  the  midsea  "  Goldseeker  "  dredgings  from  stations 
adjacent  to  the  Northern  Area  of  the  "  Huxley" 

Of  the  other  species  recorded  in  the  list  a  few  have  more  than 
a  passing  interest.  (1)  Nubecularia  lucifuya  Defrance  is  a  southern 
form,  not  previously  recorded  on  the  S.  and  E.  coast  of  Britain 
beyond  Bognor,  Sussex.  A  few  specimens  have  been  dredged  by 
the  "Goldseeker  "  in  the  Moray  Firth  and  Shetland  seas,  and  these 
two  records,  from  intermediate  localities,  are  therefore  of  interest. 

The  same  remarks  apply  to  (9)  Massilina  secans  d'Orbigny  sp. 
This  is  the  most  abundant  and  typical  Miliolid  of  the  shore 
sands  and  shallow  water  all  round  the  S.  and  W.  coast-line. 
There  are  few  records  of  shore  sands  on  the  E.  coast,  but  the 
species  occurs  at  Cromer  and  St.  Andrews  (Fife)  and  is  abundant 
at  Scapa  in  Orkney  in  shore  sand.  It  is  extremely  rare  in  the 
"  Goldseeker ■'"  North  Sea  dredgings,  but  the  few  specimens  found 
were  from  a  Station  (39B)  near  the  "  Huxley  "  Northern  Area. 
Its  absence  from  the  Southern  Area  is  noticeable,  and  probably 
due  to  the  muddiness  of  the  deposit. 

(12)  Comuspira  striolata  Brady.  The  specimen  from  Haul  767 
(Northern  Area)  is  of  the  very  fragile  and  etiolated  type  abun- 
dant in  many  of  the  "  Goldseeker  "  dredgings  from  the  deeper 
North  Sea. 

(13)  Comuspira  diffusa  Heron- Allen  and  Earland  *  (P\.  11, 
fig.  1).  The  specimens  of  this  form,  which  has  been  recently 
described  by  us,  were  large  and  quite  typical,  but  few  in  number. 
The  Northern  Area  is  quite  close  to  the  "  Goldseeker  "  Stations  at 
which  it  is  most  abundant,  but  the  species  is  sparingly  distributed 
round  the  British  coast. 

(14)  Bathysiphon  argenteus,  (62)  Layena  cymbula  (PL  10, 
figs.    10-12),    (84)  Layena  unyuis,  and  (117)  Discorbina  Praeyeri 

*  "  On  some  Foraminifera  from  the  North  Sea,  etc.,  dredged  by  the 
Fisheries  Cruiser. "  Goldseeker  "  (International  North  Sea  Investigations — 
Scotland).  III.  On  Comuspira  diffusa,  a  new  type  from  the  North  Sea." 
Journ.  R.  Mior.  Soc.,  1913,  pp.  272-6,  pi.  xii. 


130     E.    HERON-ALLEN    AND    A.     EARLAND    ON    SOME    FORAMINIFERA 

are  new  forms  discovered  first  by  us  in  "  Goldseeker  "  dredgings. 
They  are  described  and  figured  in  our  report  on  the  Foraminifera 
of  the  Clare  Island  Survey  (Proc.  Roy.  Irish  Acad.,  1913,  vol.  xxxi., 
No.  64). 

(20)  Reophax  nodulosa  Brady  (PI.  10,  fig.  1)  is  extremely 
rare  as  a  British  species.  It  has  been  recorded  from  the  Clyde 
Area  and  Skye  by  Robertson  and  from  the  Estuary  of  the  Dee 
by  Siddall.  The  British  specimens  are  very  minute,  but  in  the 
deep  sea  it  attains  a  great  size,  up  to  1  in.  in  length. 

(23)  Haplophragmium  anceps  Brady,  another  deep-water  form, 
is  of  rare  occurrence  in  British  waters.  It  has  been  recorded 
from  shore  sands  at  Southport  (Chaster)  and  Bognor  (Earland), 
and  we  have  recently  dredged  it  in  the  Clare  Island  Area. 

(25)  Haplophragmium  crassimargo  Norman  (PL  10,  fig.  5-6), 
a  large  and  very  robust  form  closely  allied  to  H.  canariense 
d'Orbigny  sp.,  is  the  typical  Haplophragmium  of  the  deeper  parts 
of  the  North  Sea,  and  is  abundant  in  many  of  the  "  Goldseeker  " 
dredgings. 

(27)  Thurammina  papillata  Brady.  The  single  specimen  re- 
corded from  Haul  369  in  the  Southern  Area  is  extremely  small, 
but  quite  typical  of  the  spherical  type  (cf.  Brady,  Foraminifera 
of  the  u  Challenger"  1884,  pi.  xxxvi.,  fig.  7).  The  papillae  are 
prominent  and  very  numerous.  The  genus  Thurammina  is 
abundant  and  very  variable  in  the  deep  water  of  the  North  Sea 
to  the  N.E.  of  Shetland,  but  very  rare  in  the  central  North  Sea. 

(28)  Ammodiscus  incertus  d'Orbigny.  All  the  specimens  are 
very  minute  and  of  a  light-grey  colour.  The  genus  is  very 
sparingly  distributed  in  all  the  "  Goldseeker  "  dredgings  from  the 
North  Sea,  and  all  the  specimens  are  minute.  In  the  Faroe 
Channel,  however,  it  attains  its  full  dimensions. 

(35)  Spiroplecta  biformis  Parker  and  Jones  sp.  (PI.  10, 
fig.  9).  The  single  specimen  of  this  rare  form,  recorded  from 
Haul  772  in  the  Northern  Area,  is  noticeable  for  the  rapid 
increase  in  size  of  the  Textularian  chambers  following  the  Spiro- 
plectine  portion  of  the  test. 


FROM    THE    NORTH    SEA.  131 

(37)  Vemeuilina  polystropha  Reuss  sp.  All  the  specimens  of 
this  species,  one  of  the  most  abundant  and  typical  North  Sea 
forms,  belong  to  the  large  coarsely  built  type,  except  in  Haul  770 
Northern  Area,  where  also  a  few  individuals  of  the  minute  and 
delicate  type  described  and  figured  by  us  in  the  Clare  Island 
Survey  Report  were  observed. 

(38)  Clavulina  obscura  Chaster  (PI.  10,  figs.  7,  8),  occurs  in 
both  Areas,  but  whereas  the  Northern  Area  yielded  only  a  single 
specimen,  the  species  attains  an  extraordinary  development  both 
as  regards  size  and  abundance  in  Haul  871  in  the  Southern 
Area.  It  is  usually  a  very  rare  species,  though  widely  distributed 
round  our  coasts  in  muddy  gatherings. 

(91)  Lingulina  carinata  d'Orbigny.  The  single  specimen  from 
Haul  869  Southern  Area  is  of  a  minute  type.  Such  specimens 
occur  sparingly  in  most  of  the  "  Goldseeker"  dredgings  from 
muddy  areas. 

(92)  Marginulina  glabra  d'Orbigny.  The  single  specimen  from 
Haul  871  is  very  minute.  Rut  the  species  is  abundant  and 
attains  a  very  large  size  in  the  deeper  waters  of  the  North  Sea 
to  the  N.E.  of  Shetland. 

(106)  Globigerina  rubra  d'Orbigny  (PI.  10,  figs.  13-15).  This 
species  is  one  of  the  commonest  Globigerinae  all  over  the  North 
Sea  and  often  forms  a  large  proportion  of  the  finer  material 
dredged  on  muddy  bottoms. 

(110)  Discorbina  Chasterl  Heron-Allen  and  Earland.  Origin- 
ally described  by  the  late  Dr.  Chaster  of  Southport  under  the 
specific  name  Discorbina  minutissima.  This  specific  name  having 
been  previously  used  by  Seguenza  for  another  form,  we  have 
(in  the  Report  on  the  Foraminifera  of  the  Clare  Island  Survey) 
renamed  the  species  after  its  original  discoverer.  It  is  of  common 
occurrence  in  muddy  dredgings  from  all  the  shallow  coastal 
deposits  of  the  North  Sea  and  around  the  Western  shores  of 
Britain  generally. 

(112)  Discorbina  Mediterranensis  d'Orbigny  sp.  and  (115)  Dis- 
corbina Peruviana  d'Orbigny  sp.  are  old  specips  which  we  propose 


132     E.    HERON-ALLEN    AND   A.     EARLAND   ON    SOME    FORAMINIFERA 

to  revive  for  sub-types  of  the  "  rosacea  "  group,  under  a  scheme 
which  is  fully  explained  in  our  Clare  Island  Report. 

(133)  Polystomella  crispa  Linne  sp.  The  occurrence  of  only  a 
single  specimen  of  this  species  in  the  Southern  Area  is  very 
noticeable,  as  it  might  have  been  expected  to  occur  more  plenti- 
fully so  near  the  coast.  But  as  regards  the  single  specimen  from 
the  Northern  Area,  its  occurrence  there  is  still  more  noteworthy, 
as  the  species  is  extremely  rare  in  the  "  Goldseeker "  dredgings 
even  in  the  proximity  of  the  coast  and  none  have  been  previously 
found  so  far  out  at  sea  as  this.  The  specimen  is,  however, 
very  water- worn,  and  may  have  been  current-borne  for  a  great, 
distance. 


List  of  "  Huxley  "  Stations  from  which  Material 

was  Examined. 


( 


A.  Northern   or  Outer  Area — lying  N.N.E.  of  the   Dogger 
Bank. 

1.  Haul  767,  Station  xix.,  56°  53'  N.,  3°  43'  E.     Dredging  made 

July  22nd,  1906,  in  35  fathoms,  to  the  S.W.  of  the  Great 
Fisher  Bank. 

2.  Haul  770,  Station  xxii.,  56°  50'  N.,  3°  59'  E.     Dredging  made 

July  24th,  1906,  in  31  fathoms,  on  the  Inner  Shoal  to  the 
S.  of  the  Great  Fisher  Bank. 

3.  Haul  772,  Station  xxv,  56°  34'  N.',  3°  53'  E.     Dredging  made 

July  24th,    1906,  in   37  fathoms,  to  the   S.   of  the  Inner 
\         Shoal  and  Great  Fisher  Bank. 

/    B.  Southern  or  Inner  Area — lying  W.  of  the  Dogger  Bank, 
between  the  Bank  and  the  English  coast. 

4.  Haul  869,  Station  xlii.,  55°  6'  N.,  1°  2'  W.     Dredging  made 

July  23rd,  1907,  in  43  fathoms,  off  Blyth,  Northumberland. 

5.  Haul  871,  Station  xliv.,  54°  59'  N.,  1°  7'  W.     Dredging  made 

July  23rd,  1907,  in  34  fathoms,  off  Tynemouth. 

6.  Haul  882,  Station   (?),  55°  21'  N.,  1°  10  'W.     Dredging  made 
\         July  26th,  1907,  in  45  fathoms,  off  Alnmouth. 


FROM    THE    NORTH    SEA. 


133 


The  asterisk  denotes  the  presence  of  fossil  specimens.  1  =  a  single 
specimen  only.  V  C  =  very  common.  C  =  common.  F  ==  frequent.  R  = 
rare.     VE  =  very  rare. 


MlLIOLIDAE. 

Sub-family  Nubecv larinae. 

1.  Xubecularia  lucifuya  Def ranee 

Sub-family  Miliolin inae. 

2.  Biloculina  depressa  d'Orbigny 

3.  Biloculina  rinyens  Lamarck  sp. 

4.  Spiroloculina  impressa  Terquem 

5.  Miliolina  bicomis  Walker  &  Jacob  sp 

6.  Miliolina  circularis  Bornemann  sp. 

7.  Miliolina  contort  a  d'Orbigny  sp. 

8.  Miliolina  seminulum  Linne  sp. 

9.  Massilina  secans  d'Orbigny  sp. 

Sub-family  Pen  eroplid  inae. 

10.  Cornuspira  involvens  Reuss 

11.  Cornuspira  Seise  ye  nsis    Heron- Allen    & 

Earland      ...... 

12.  Cornuspira  striolata  Brady 

13.  Cornuspira  diffusa  Heron-Allen  &  Ear- 

land    

ASTRORHIZIDAE. 
Sub-family  Pilvlin inae. 

14.  Bathy siphon    aryenteus    Heron-Allen  & 

Earland 

Sub-family  Saccammininae. 

15.  Psammosphaeva  fusca  Schulze 

16.  Saccammina  sphaerica  M.  Sars 

Sub-family  Bhabdamm in i nae. 

17.  Hyperammina  ramosa  Brad}r  . 

LlTUOLIDAE. 
Sub-family  Litvolinae. 

18.  Beophax  dipluyiformis  Brady 

19.  Beopha.v  fusiformis  Williamson  sp. 

20.  Beophax  nodulosa  Brady 

21.  Beophax  scorpiurus  Montfort 

22.  Beophax  Scottii  Chaster 

23.  Haplophraymium  anceps  Brady 

24.  Haplophraymium  Canariense  d'Orbignv 

sp 

25.  Haplophrayminm  crassimargo  Xorman 

26.  Haplophraymium pseudospirale  William 

son  sp.        ..... 


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134     E.    HERON-ALLEN    AND    A.    EARLAND    ON    SOME    FORAMINIFERA 


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Sub- family  Trochammin inae. 

27.   Thurammina papillata  Brady 

1 

28.  Ammodiscus  incertus  d'Orbigny  sp. 

R 

F 

29.   Trochammina  ochracea.  Williamson  sp.  . 

F 

C 

R 

vc 

30.   Trochammina  squamata  Jones  k,  Parker 

F 

VC 

Textularidae. 

Sub-family  Textv  lari  nae. 

31.   Textularia  agglutinans  d'Orbigny  . 

VR 

32.   Textularia  conica  d'Orbigny    . 

VR 

VR 

vc 

33.   Textularia  globulosa  Ehrenberg 

Y* 

F* 

1* 

34.   Textularia  gramen  d'Orbigny  . 

VR 

35.  Spiroplecta  biformis  Parker  &  Jones  sp. . 

1 

36.   Gaudryina  filiform  in  Berthelin 

- 

F 

R 

37.    Yerneuilina polystropha  Reuss  sp. 

vc 

R 

VC 

VC 

VC 

VC 

38.   Clavulina  obscura  Chaster 

1 

F 

VC 

Sub-family  Bu limin inae. 

39.  Bulimina  aculeata  d'Orbigny 

VR 

R 

c 

40.  Bulimina  elegans  d'Orbigny    . 

►         • 

F 

C 

R 

41.  Bulimina  elegantissima  d'Orbigny 

c 

R 

F 

42.  Bulimina  fusiformis  Williamson 

vc 

C 

vc 

VC 

VC 

VC 

43.  Bulimina  marginata  d'Orbigny 

c 

F 

c 

F 

F 

C 

44.  Bulimina,  ovata  d'Orbigny 

F 

45.  Bulimina pupoides  d'Orbigny 

R 

R 

1 

46.    Virgvlina  Schreibersiana  Czjzek 

R 

R 

47.  Bolivina  difformis  Williamson  sp. 

VR 

VR 

1 

48.  Bolivina  dilatata  Reuss  . 

R 

C 

C 

49.  Bolivina  nobilis  Hantken 

1 

1 

50.  Bolicina  plicata  d'Orbigny 

1 

VR 

F 

F 

51.  Bolivina  punctata  d'Orbigny  . 

C 

R 

F 

F 

52.  Bolivina  textilarioides  Reuss  . 

R 

53.  Bolivina  variabilis  Williamson  sp. 

R 

F 

Sub-family  Cassibulin inae. 

54.   Cassidulina  crassa  d'Orbigny  . 

F 

F 

F 

F 

55.   Cassidulina  laevigata  d'Orbigny 

VR 

R 

1 

56.   Cassidulina  subglobosa  Brady. 

R 

R 

F 

Lagenidae. 

Sub-family  Lag  en  inae. 

57.  Lagena  acuticosta  Reuss 

VR 

58.  Lagena  apiculata  Reuss  sp.     . 

VR 

2 

59.  Lagena  bicarinata  Terquem  sp. 

1 

60.  Lage?ia  clavata  d'Orbigny  sp. 

R 

C 

F 

61.  Lagena  costata  Williamson  sp. 

F 

R 

62.  Lagena  cymbula  Heron-Allen  &  Earland 

1 

63.  Lagena  distoma  Parker  &  Jones 

1 

R 

C 

VC 

64.   Lagena  fasciata  Egger    . 

R 

VR 

1 

65.  Lagena  globosa  Walker  &  Jacob  sp. 

1 

VR 

F 

1 

66.  J^agena  gracUlima  Seguenza  sp. 

j 

1 

C 

FROM    THE    NORTH    SEA. 


135 


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67.  Lagena 

68.  Lagena 

69.  Lagena 
Lagena 

79.  Lagena 

71.  Lagena 
Lagena 

72.  Lagena 

73.  Lagena 

74.  Lagena 

75.  Lagena 

76.  Lagena 

77.  Lagena 

78.  Lagena 

79.  Lagena 

80.  Lagena 
81  Lagena 

82.  Lagena 

83.  Lagena 

84.  Lagena 

85.  Lagena 


gracilis  Williamson    . 
hexagona  Williamson  sp. 
laevigata  Reuss  sp.     . 
laevigata,  trigonal  form 
laevis  Montagu  sp. 
lagenoides  Williamson  sp. 
lagenoides,  trigonal  form. 
lineata  Williamson  sp. 
lucid  a  Williamson  sp. 
Malcomsonii  J.  Wright 
marginata  Walker  &  Boys  sp. 
marginato-perforata  Seguenza 
Orbignyana  Seguenza  sp. 
ornata  Williamson  sp. 
quadrata  Williamson  sp. 
se mist riat a  Williamson 
squamosa  Montagu  sp. 
striata  d'Orbigny  sp.  . 
sulcata  Walker  &  Jacob  sp. 
unguis  Heron-Allen  *Sc  Earland 
Williamsuni  Alcock  sp. 


Sub-family  Xodosarinae. 

86.  Xodosaria  Jiliformis  d'Orbigny 

87.  Xodosaria  pan perata  d'Orbigny 

88.  Xodosaria  pltbeia  Reuss. 

89.  Xodosaria p grula  d'Orbigny    . 

90.  Xodosaria  scalaris  Batsch  sp. 

91.  Lingulina  carinata  d'Orbigny 

92.  Marginulina  glabra  d'Orbigny 

93.  Vaginuliiia  legumen  Linne  sp. 

94.  Cristellaria  acut  auricular  is    Fichtel   & 

Moll  sp 

95.  Cristellaria  costata  Ficbtel  &  Moll  sp. 

96.  Cristellaria  rotulata  Lamarck  sp.  . 

Sub-family  Poltmorp hi n inae. 

97.  Polgmorphina  compressa  d'Orbigny 

98.  Polgmorphina  lactea  Walker  &  Jacob  sp 

99.  Polgmorphina  oblonga  Williamson  . 

100.  Polgmorphina  sororia  Reuss    . 

101.  T'vigerina  angulosa  Williamson 

102.  Ucigerina  pygmcea  d'Orbigny 

Olobigerixidae. 

103.  Globigerina  aequilateralis  Brady    . 

104.  Globigerina  bulla  ides  d'Orbigny 

105.  Globigerina  cretacea  d"Orbigny 

106.  Globigerina  rubra  d'Orbigny  . 

107.  Pullenia  xphaeroides  d'Orbigny  sp. 


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136     B.    HERON-ALLEN    AND   A.    EARLAND   ON    SOME    FORAMTNIFERA 


ROTALIDAE. 
Sub-family  Spj rillin inae. 

108.  Spirillina  vivipara  Ehrenberg 

Sub-family  Rotalinae. 

109.  Patellina  corrugata  Williamson 

110.  Discorbina  Chasteri  Heron-Allen  &  Ear- 

land    ...... 

111.  Discorbina  globularis  d'Orbigny 

112.  Discorbina  Mediterranensis d'  Orbigny  sp 

113.  Discorbina  nitida  Williamson  sp.   . 

114.  Discorbina  obtusa  d'Orbigny  sp. 

115.  Discorbina  Peruviana  d'Orbigny  sp. 

116.  Discorbina  poly  rraphes  Reuss 

117.  Discorbina  Praegeri  Heron- Allen  &  Ear 

land   ...... 

118.  Truncatulina  lobatida  Walker  &  Jacob 

sp.      ..... 

119.  Truncatulina  refulgens  Montfort  sp. 

120.  Truncatulina  Ungcriana  d'Orbigny  sp, 

121.  Pulvimdina   haliotidea   Heron-Allen   & 

Earland      ..... 

122.  Pulvinulina  Karsteni  Reuss  sp. 

123.  Rotalia  Beccarii  Linne  sp. 

124.  Rotalia  orbicularis  d'Orbigny 

NUMMULINIDAE. 
Sub-family  Poltstomellinae. 

125.  Nonionina  asterizans  Fichtel  &  Moll  sp. 

126.  Nonionina   depressula  Walker  &  Jacob 

SP 

127.  Nonionina  pauper ata  Balkwill  &  Wright 

128.  Nonionina  scapha  Fichtel  &  Moll  sp. 

129.  Nonionina  stelligera  d'Orbigny 

130.  Nonionina  turgida  Williamson  sp.  . 

131.  Nonionina  umbilicatula  Montagu  sp. 

132.  Polystomella  striatopunctata    Fichtel  & 

Moll,  sp 

133.  Polystomella  crispa  Linne  sp. 


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FROM   THE   NORTH    SEA.  137 

DESCEIPTION   OF   PLATES. 

Plate  10. 

Fig.  1.  Reophax  nodulosa  Brady,  x   120. 
„    2,  3,  4.  Haplop>hragmium  pseudospi?*ale  Will,  sp.,   x  40. 
,,     5,  6.  Haplophragmium  crassimargo  Norman,  x  30. 
,,     7,  8.   Clavulina  obscura  Chaster,   x  100. 
„     9.  Spiroplecta  b iformis  Parker  &  Jones  sp.,  x  120. 
„  10.  Lagena  cymbida  Heron- Allen  &  Earland,  superior  view, 

X  250. 
„  11.  Lagena   cymbida  Heron- Allen  &  Earland,  inferior  view, 

x  250. 
,,12.  Lagena    cymbida    Heron-Allen   &    Earland,    edge    view, 

x  250. 
„  13,  14,  15.   Globigerina  rubra  d'Orbigny,   x  120. 

Plate  11. 

Fig.  1.   Cornuspira  diffusa   Heron-Allen  &   Earland,   x  5,  illus- 
trating the  protean  habit  of  growth. 

„  2.  Heavy  portion  of  ooze  from  Hilte  Fjord,  Norway,  260 
metres,  "  Goldseeker"  Haul  141,  depth  260  metres. 
Most  of  the  foraminifera  have  been  removed  by 
elutriation,  leaving  a  residuum  of  faecal  pellets  of 
Annelid  origin  (1  Hyalinoecia  sp.)  x  45. 

,,     3.  Rounded    sand-grains    from    "Huxley"    material,  x  12. 

,,  4.  Normal  angular  grains  typical  of  shore  gatherings  and 
shallow-water  deposits,  x  12. 

,,  5.  Crystalline  sand-grains  from  a  dredging  in  the  Hauraki 
Gulf,  New  Zealand,  x  1 2.  Such  crystalline  grains  are 
very  rare  except  in  the  neighbourhood  of  volcanic 
deposits. 

[It  is  greatly  to  be  hoped  that  the  writers  will  find  it  possible 
for  them  to  examine  in  similar  detail  a  certain  number  of  the 
remaining  "Huxley"  dredgings,  of  which  some  six  hundred  are 
available,  taken  from  the  North  Sea  south  of  the  Forth.  Their 
present  paper  shows  that  in  their  practised  hands  results  of  con- 
siderable interest  may  be  expected  should  this  be  done.     I  would 

Journ.  Q.  M.  C,  Series  II.— No.  73.  10 


138     E.    HERON-ALLEN    AND    A.    EARLAND    ON    SOME    FORAM1NIFERA. 

submit  for  their  consideration  the  examination  of  selected  stations 
along  lines  drawn  east  and  west,  in  the  manner  of  sections.  A 
large  proportion  of  these  in  all  probability  could  be  dealt  with 
in  a  very  summary  manner,  but  the  remainder  might  yield 
results  of  importance  as  to  the  relation  of  distribution  to  salinity, 
depth,  temperature  and  current,  possibly  even  affording  evidence 
of  the  main  trend  of  the  currents,  which  would  provide  a  welcome 
check  on  other  observations  carried  out  by  current-meters  and 
drift -bottles. 

In  regard  to  the  samples  which  they  have  examined  from 
the  deep  water  east  of  the  Dogger  it  may  be  remarked  that  the 
Admiralty  tide  charts  show  but  low  rates  of  velocity  in  the 
district,  which  has  moreover  a  greater  depth  of  water  than  one 
would  expect  to  be  consistent  with  frequent  wave  action  at  the 
bottom.  Recent  current  measurements  carried  out  by  the 
Board  of  Agriculture  and  Fisheries  have  also  failed  to  detect 
any  marked  resultant  current.  It  may  therefore  be  suggested 
that  the  sub-polish  attained  by  the  rounded  grains  is  not  in 
all  cases  due  to  attrition  on  the  spot.  The  freedom  of  the 
adjacent  Dogger  Bank  from  silt,  a  grade  of  material  found  in 
high  percentage  on  either  side,  may  perhaps  be  explained  by 
the  finer  particles  churned  up  and  held  in  suspension  by  wave 
action  during  storms  being  gradually  washed  into  the  deeper 
water :  some  segregation  of  the  rounder  grains  may  take  place 
in  the  same  manner.  A  thorough  geological  examination  of 
the  area,  especially  of  the  Scottish  coast,  might  also  show  to 
what  extent,  if  any,  the  grains  result  from  the  disintegration 
of  certain  definite  sandstone  rocks. 

For  the  action  of  wave  and  current  in  the  Southern  Bight 
(North  Sea  south  of  53°)  the  collection  of  samples  as  a  whole 
furnish  good  evidence ;  the  material  is  to  a  great  extent  graded 
as  in  a  levigator,  the  average  diameter  of  the  sand  particles 
diminishing  as  the  speed  of  the  current  declines.  Yet  even  in 
this  district,  with  its  shallower  waters  and  far  more  powerful 
currents,  the  upper  limit  of  size  of  the  particles  affected  is  soon 
reached,  and  one  feels  in  consequence  the  need  of  searching  for 
other  causes  before  explaining  the  rotundity  of  certain  of  the 
grains  near  the  Dogger  by  tidal  action  alone. — J.   O.   Borley.] 

r— . , . _____ _ , _, 

jQurn.  Quefcett  Mkyo-icopical  CliLib,  Ser.  2,  YoLX.IL,  Np.  73,  November  ]£>Z3, 


Journ.  Q.M.C. 


Ser.  2,   Vol.  XII.,   PI.  10. 


FORAMINIFERA    FROM    THE    NORTH    SEA, 


Tourn.  Q.M.C. 


Ser.  2,  Vol.  XII.,   PI.  11. 


BpX^Smt 

N  ■     • 

A^fc.  ^*>  ^?         1 

P> 

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*^        .  - 

IF 

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P^B            .  a^P^H                              P^PAw^a.  .^^Pmb                                       ^■■1  P^H              t»  *^?  1 
^^^■B                                                                                 PMV                     «■  PS        -k^_   fi^W 

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BS^;          Kpjfe/w          ^^^^       Pfet.      ^ 

W*iM           PJ*V»^  PA.  •3L  ■>  Bl 

4                                                  fe^                                    ^ 

CORNUSPIRA   DIFFUSA    HERON-ALLEX    AND    EaRLAND. 

Sand-grains,  etc.,  from  the  Bottom-deposits, 


139 


DESCRIPTION  OF  ARRHENURUS  SOOURFIELDI  AND 
ACERCUS  LONG/TARSUS  :  TWO  NEW  SPECIES  OF 
WATER-MITES. 

By  C.  D.  Soar,  F.L.S.,  F.R.M.S. 

(Read  April  22nd,  1913). 

Plates  12,  13. 

Arrhenurus  Scourfieldi  sp.  nov. 

In  the  autumn  of  1912,  Mr.  D.  J.  Scourfield  handed  me  a  tube 
containing  a  few  water-mites,  which  he  had  taken  from  fresh 
water  in  Cornwall.  Amongst  them  was  one  which  was  quite  new 
to  me,  a  male  Arrhenurus,  of  the  sub-genus  Megalurus.  As  I 
cannot  find  that  it  has  been  described  or  figured,  I  propose  to  name 
it  after  Mr.  Scourfield. 

Arrhenurus  Scourfieldi  sp.  nov. — The  specimen  is  a  male ; 
length  1-04  mm.,  greatest  breadth  about  064  mm.  In  outline 
the  body  is  long  ;  anterior  corners  well  cut  off,  and  slightly  bent 
inwards ;  sides  almost  straight,  tapering  towards  the  posterior 
margin.  The  posterior  margin  is  divided  by  a  central  cleft  into 
two  well-rounded  portions. 

The  skin  is  covered  with  small  papillae  ;  the  dorsal  surface  has 
the  usual  indented  sunk  line  common  to  members  of  this  genus, 
and  several  dermal  glands  both  inside  and  outside  the  sunken  line. 
Looked  at  from  above  there  is  a  small  wing-like  process  about 
0'15  mm.  from  the  posterior  margin. 

The  colour  is  a  dark  blue-green  with  brown  markings  on  the 
dorsal  surface.  The  epimera  are  slightly  lighter  in  colour.  It 
is  of  the  same  colour  as  Arrhenurus  globator. 

The  eyes  are  very  dark  red,  close  to  margin,  about  0*32  mm. 
apart.     Capitulum,  about  0"20  mm.  long. 

The  first  pair  of  epimera  are  joined  together  at  the  back  of  the 
capitulum,  the  second  pair  pressed  close  to  first  pair  so  that  what 


140      C.    D.    SOAR,    DESCRIPTION    OF    ARRHENURUS  SCOURFIELDI   AND 


is  known  as  the  first  two  pairs  of  the  epimera  form  one  distinct 
group. 

The  posterior  pair  are  in  two  distinct  groups  placed  about 
0*05  mm.  behind  the  second  pair. 

The  genital  area  lies  about  0*08  mm.  behind  the  fourth  pair  of 
epimera,  the  plates  stretching  the  whole  distance  across  the 
body  of  the  mite.  The  length  of  each  plate  is  about  0*25  mm., 
tongue  shaped  and  covered  with  numerous  acetabula. 

The  legs  are  of  the  usual  structure  of  the  genus  with  the  spur 
on  the  fourth  segment  of  the  fourth  leg.  They  are  strong  and 
well  provided  with  swimming  hairs.  The  first  leg  about  0"60  mm. 
long,  fourth  leg  0'84  mm. 

Locality  :  Near  the  Lizard,  Cornwall,  1912.     Female  unknown. 

Acercus  longitarsus  sp.  nov. 

Acercus  longitarsus  sp.  nov. — The  body  is  0*76  mm.  in  length  ; 
breadth  about  0'54  mm.,  ovate.  The  colour  is  a  pale  straw 
yellow  with  dark-brown  markings.  There  is  a  reddish-yellow 
wedge-shaped  patch  in  the  centre  of  the  dorsal  surface. 

The  epimera  cover  nearly  the  whole  of  the  ventral  surface,  and 
differ  from  that  of  the  type  species  Acercus  omatits  in  the  follow- 
ing important  particulars.  Firstly,  the  genital  area  instead  of 
being  situated  in  a  small  bay  on  the  posterior  margin  of  the 
epimera  as  in  Acercus  ornatus,  is  partly  enclosed  in  an  angular 
space  formed  by  the  posterior  edge  of  the  epimera  being  turned  at 
a  low  angle  towards  the  median  line.  Secondly,  near  the  base 
of  the  epimera  are  two  small  incurvations,  one  on  each  side,  which 
are  not  found  in  the  type  species  of  this  genus.  They  run  into 
the  epimera  about  O05  mm.  The  actual  genital  area  itself  is 
similar  to  type  species,  having  six  acetabula  arranged  in  the  same 
way. 

The  palpi  are  about  0*45  mm.  in  length.  On  the  flexar  edge 
of  the  fourth  segment  are  placed  two  long  hairs,  a  little  distance 
apart  ;  they  are  close  together  in  Acercus  ornatus. 

The  legs  of  the  species  form  the  most  striking  departure  from 
the  type  form  and  in  fact  all  other  species  of  this  genus ;  on 
comparison  it  will  be  seen  that  the  tarsi  are  enormously  developed 
in  length. 

The  last  segment  of  the  first  and  second  pairs  of  legs  are  longer 


ACERCUS  LONGITARSUS  \     TWO    NEW    SPECIES    OF    WATER-MITES.      141 

than  usual,  but  it  is  the  last  segment  of  the  fourth  pair  which 
shows  the  great  increase  in  length.  The  tarsi  measure  as  much 
as  0*60  mm.,  which  is  more  than  the  fourth  and  fifth  segment 
together. 

The  first  leg  is  about  1*40  mm.  in  length,  the  second  about  1*30, 
the  third  about  0"90,  the  fourth  about  1-58. 

The  eyes,  large  and  distinct,  are  very  dark  red  and  about  0'14 
mm.  apart. 

This  mite  can  be  most  easily  recognised  by  the  length  of  the 
tarsus  of  the  fourth  pair  of  legs.  I  propose  naming  it  Acercus 
longitarsus. 

Locality  :  South  Devonshire  (female  unknown). 

There  are  also  one  or  two  additions  to  be  made  to  British 
records.  Mr.  Williamson,  F.R.S.E.,  in  working  out  the  material 
on  the  Genus  Sperchon,  has  found  that  we  have  two  species  quite 
new  to  the  British  area,  and  two  that  up  to  the  present  have  only 
been  recorded  for  Ireland. 

1st.  Sperchon  clupeifer  Pier. 
Sub-genus :  Hispidosperchon. 
Locality  :  Oban  and  Norfolk  Broads. 

2nd.  Sperchon  tenuabilis  Koen. 

Sub-genus :  Hispidosperchon. 

Locality :  Oban.  Recorded  for  Ireland  by  Halbert  in  Clare 
Island  survey. 

3rd.  Sperchon  papillosus  Sig  Thor. 
Sub-genus  :  Squamosus. 
Locality  :  Oban.     Recorded  for  Ireland  by  Halbert. 

4th.  Sperchon  Thienemanni  Koen. 
Sub -genus :  Rugosa. 
Locality  :  Derbyshire. 


142    c.  d.  soar,  description  of  two  new  species  of  water-mites. 

Description  of  Plates. 

Plate  12. 

Fig.  1.  Arrhenurus  Scourfieldi  sp.  nov. — Dorsal  surface  of  male 
drawn  from  a  living  specimen,   x   50. 
„    2.  Arrhenurus  Scourfieldi  sip.  nov. — Ventral  surface  of  same 
drawn  after  mounting. 

Plate  13. 

Fig.  1.  Acercus  longitarsus  sp.  nov. — Dorsal  surface  of  males, 
X  58. 
„    2.  Acercus  longitarsus  sp.  nov. — Ventral  surface  of  same, 

x  58. 
„    3.  Acercus  longitarsus  sp.  nov. — Palpi  of  same,  X   150. 


Jovrn.  Quelett  Microscopical  Club,  Ser.  ?,  Vol.  XII.,  Ho.  73,  November  1913 


Journ.  Q.M.C. 


Ser.  2,  Vol.  XII.,  PI.  12. 


^A7     2 

C.  D.  S.,  del.  adnat. 

$  Arrhenurus  Scourfieldi  sp.  nov. 


Journ.  Q.M.C. 


Ser.  2,  Vol.  XII.,   PI.   13. 


C.  D.  S.,  del.  ad  nat. 

S    ACERCUS  LONGITARSUS    sp.  nOV. 


143 


THE    COLLECTION    AND    PRESERVATION    OF    THE 

HYDROIDA. 

By  G.  T.  Harris. 

Communicated  by  C.  J.  IT.  Sidwell. 
{Bead  April  22nd,  1913.) 

The  Hydroida  are  too  well  known,  as  both  beautiful  and  interesting 
objects,  to  need  any  eulogy  on  my  part.  If  they  have  received 
less  attention  from  the  members  of  the  Q.M.C.  than  some  other 
groups,  it  is  probably  due  to  the  fact  that  the  Hydroida  evince 
a  decided  and  conservative  preference  for  salt  water,  and  show 
no  inclination  whatever  for  the  uneventful  environment  of 
metropolitan  ponds.  Hence,  those  who  would  collect  them  must 
seek  them  where  they  may  be  found,  i.e.  from  tidal  limits  to  as 
many  fathoms  as  the  collector's  means  or  stomach  will  allow. 

Bearing  in  mind  that  this  paper  is  written  more  for  the  help 
of  the  novice  than  as  a  communication  offering  original  matter, 
I  would  safeguard  myself  from  any  charge  of  carelessness  by 
warning  the  uninitiated  that  collecting,  say,  rotifers,  and  col- 
lecting hydroids  are  two  totally  dissimilar  things.  Pond 
collecting  is  a  more  or  less  safe  and  a  very  pleasant  recreation ; 
hydroid  collecting  is  rarely  enjoyable,  and  may  be,  by  a  little 
carelessness,  rendered  adventurous.  The  one  could  be  prosecuted 
in  a  silk  hat  and  a  frock  coat  if  desired,  without  seriously  giving 
the  wearer  away ;  the  costume  best  suited  to  the  other  tries  the 
loyalty  of  one's  staunchest  friend.  Dredging  is,  perhaps,  less 
open  to  contumely  than  shore  collecting ;  the  nature  of  the 
operation  secures  to  the  collector  a  considerable  measure  of 
privacy,  while  the  examination  of  the  spoil  can  be  carried  out 
in  attitudes  familiar  to  oneself  and  those  around.  Shore  collect- 
ing permits  of  no  compromise,  and  the  positions  most  consonant 
with  successful  collecting  are  mainly  such  as  contribute  materially 
to  the  entertainment  of  the  seaside  visitor  waiting  to  be 
amused. 

I    think    it    may  be  taken   for  granted   that,  in  spite   of   its 


144  G.    T.    HARRIS    ON    THE    COLLECTION    AND 

obvious  drawbacks,  shore  collecting  will  appeal  to  the  amateur 
collector  rather  than  the  more  professional  method  of  dredging. 
It  entails  less  expense,  requires  less  intimacy  with  the  local 
conditions,  and,  for  a  given  amount  of  time  expended,  probably 
yields  a  richer  harvest ;  finally,  the  physiological  effects  of  shore- 
collecting  are  not  so  overwhelming  as  are  those  sometimes 
connected  with  dredging.  At  the  same  time,  no  serious  student 
of  the  Hydroida  can  ignore  the  dredge  as  a  means  of  collecting, 
as  a  large  number  of  species  can  only  be  obtained  by  its  aid. 
However,  for  the  reassurance  of  those  who  confine  themselves  to 
shore  collecting,  I  may  state,  as  the  result  of  long  experience, 
that  on  a  favourable  shore  the  number  of  species  to  be  found 
between  tide-marks  is  very  great,  and  amongst  them  are  many  of 
the  most  beautiful  forms  amongst  the  Hydroida.    - 

Unfortunately  no  precise  directions  can  be  given  for  successful 
shore  collecting.  It  is  entirely  a  matter  of  experience,  and  even 
the  practised  collector  may  fail  dismally  until  he  has  learnt  the 
shore  upon  which  he  is  engaged.  Why  hydroids  should  be  found 
plentifully  in  a  certain  section  of  shore,  yet  be  absent  from  the 
same  shore  a  quarter  of  a  mile  away,  with  apparently  the  same 
conditions,  I  am  unable  to  say,  yet  such  appears  to  be  the  case.  In 
my  own  district,  where  rock-pools  are  plentiful,  I  have  a  case 
in  point.  Coryne  vaginata,  one  of  the  commonest  littoral 
hydroids  along  the  south  coast,  occurs  in  two  or  three  of  the 
larger  pools  of  a  certain  locality,  yet  although  the  rock-pools  to 
the  right  and  left  for  some  distance  are,  as  far  as  I  can  see, 
identical,  no  Coryne  occurs  in  them.  Nor  is  this  accidental,  or 
peculiar  to  one  season,  as  I  have  been  able  to  go  to  these 
particular  pools  for  the  last  six  years  with  the  certainty  of 
obtaining  Coryne  vaginata.  Some  years  ago  when  collecting  at 
Criccieth,  in  North  Wales,  I  spent  day  after  day  laboriously 
trying  to  collect  hydroids  where  none  grew ;  finally,  I  transferred 
my  operations  to  a  less  likely  looking  section  of  the  shore,  and 
collected  hydroids  during  the  remainder  of  my  visit  over  a  very 
limited  area.  An  instance  singularly  illustrative  of  this  elusive 
quality  of  shore  collecting  recently  came  under  my  notice,  which 
may  serve  to  impress  upon  inexperienced  collectors  the  desirability 
of  not  jumping  too  hastily  to  the  conclusion  that  they  are  on  a 
barren  shore.  A  party  of  professional  naturalists  spent  the 
whole  of  one  summer  in   investigating  the  fauna   of  a  certain 


PRESERVATION    OF    THE    HYDRQIDA.  145 

section  of  coast,  the  results  of  which  were  embodied  in  a  report. 
The  shore  collecting  was  apparently  confined  to  one  spot,  from 
which  but  one  hydroid,  and  that  the  ubiquitous  Sertularia  pamila, 
was  recorded ;  yet  a  quarter  of  a  mile  farther  east  is  an  excep- 
tionally prolific  hunting-ground  at  low  tide,  where  at  least  a 
dozen  species  of  hydroids  may  be  taken.  All  this  points  to  the 
fact  that  wherever  the  hydroid-hunter  elects  to  collect  he  must, 
as  a  preliminary,  first  ascertain  that  he  has  found  the  hydroid 
ground.  When  he  has  satisfied  himself  that  he  has  done  so,  then 
collecting  may  begin  in  earnest. 

It  is  too  readily  assumed  that  only  those  shores  are  good  for 
hydroid-hunting  upon  which  rock-pools  occur.  My  experience 
leads  me  to  protest  against  this  assumption,  for  I  have  often 
had  much  better  collecting  on  shores  strewn  with  large  fucus- 
covered  boulders  than  in  some  rock-pool  districts.  Rock-pools  do 
not  necessarily  imply  the  existence  in  them  of  hydroids,  not  even 
when  they  are  clean,  sanitary  abodes.  The  rock-pools  at  Sid- 
mouth  are  excavated  in  Permian  sandstone  at  the  base  of  cliffs 
500  ft.  high,  composed  principally  of  Keuper  marl,  and  in  the 
early  summer  are  lined,  as  is  everything  in  them,  with  fine 
mud,  the  result  of  the  red  marl  falling  from  the  cliffs  during 
winter  and  being  washed  into  the  pools.  This  should  make 
hydroid  life  impossible,  but  it  does  not ;  they  seem  to  thrive  in 
it  (I  sometimes  think  upon  it),  and  cleaning  them  for  the 
microscope  thoroughly  disheartens  one.  Last  autumn  I  was 
collecting  in  South  Devon,  where  the  cliffs  are  composed  of 
hard  conglomerate,  giving  fine  clean  rock-pools.  One  rock-pool 
near  low-water  mark  especially  attracted  my  attention.  Filled 
with  clear,  limpid  water,  its  sides  draped  with  seaweeds,  every 
condition  seemed  perfect  for  hydroid  life,  and  yet  not  a  single 
specimen  was  found  in  it.  I  satisfied  myself  of  this  by  abso- 
lutely cleaning  the  pool  out,  examining  every  piece  of  seaweed, 
as  I  removed  it,  in  a  small  tank  of  water,  then  going  carefully 
over  the  sides  and  bottom  of  the  pool  with  a  lens  of  large 
diameter.  It  is  little  discrepancies  like  these  that  both  try  and 
puzzle  the  shore  collector. 

Hincks  has  given  advice  upon  shore  collecting  that  cannot 
well  be  improved  upon,  and  is  as  precise  as  such  advice  can 
be.  He  recommends  lying  at  full  length  when  collecting,  and 
however  objectionable    this   may   seem   to    be   in    theory,    it   is 


146  G.    T.    HARRIS    ON    THE    COLLECTION    AND 

thoroughly  sound  in  practice,  and  I  always  adopt  it,  carrying 
a  mackintosh  sheet  for  the  purpose.  It  should  be  recollected 
that  a  superficial  examination  of  any  rock-pool  is  not  sufficient 
to  detect  minute  species,  and  even  species  of  considerable  size, 
such  as  Plumularia  setacea,  often  harmonise  so  well  with  their 
surroundings  as  to  be  difficult  of  detection.  As  far  as  possible 
it  is  best  to  assume  a  comfortable  position,  and  then  thoroughly 
examine  the  basin  and  the  seaweeds  it  contains,  using  a  lens  of 
about  4  inches  diameter  when  necessary.  Many  rock-pools  have 
projecting  ledges  draped  with  fucus  ;  such  are  found  to  be  espe- 
cially prolific  if  well  examined.  The  fucus  should  be  turned 
right  back,  so  as  to  expose  the  sides  it  covered  and  the  under 
surface  of  the  ledge,  which  are  normally  in  deep  shade.  Sponges 
growing  underneath  may  be  scraped  off  and  examined  for  com- 
mensal hydroids.  If  long,  dark  tunnels  exist  in  the  rock,  the 
arm  should  be  pushed  up  and  the  upper  surface  of  the  rock  felt 
over  with  the  hand  for  any  adherent  masses  of  sponge,  etc., 
which  may  be  broken  off  and  examined.  This  is  a  distinctly 
sporting  method,  as  it  gives  the  crab,  when  there,  a  chance  to 
get  in  first  with  his  pincers.  Bring  him  out  and  hold  him  under 
water  in  the  rock-pool  while  you  go  over  him  carefully  with  a 
lens ;  his  carapace  will  probably  recompense  you  for  the  pinched 
finger.  Shells,  also,  should  be  carefully  examined.  The  only 
time  I  ever  took  Podocoryne  areolata  was  upon  a  shell  found  lying 
at  the  bottom  of  a  funnel-shaped  rock-pool,  and  Professor 
Allman  had  the  same  experience.  Many  species  are  so  minute 
as  to  defy  detection  by  the  ordinary  methods  of  shore  collecting 
and  are  best  obtained  by  taking  small  tufts  of  seaweeds  and 
looking  over  them  at  home  with  the  compound  microscope. 

I  have  remarked  previously  that  collecting  is  often  very  re- 
munerative on  shores  strewn  with  large  fucus-covered  boulders. 
Those  who  know  Llandudno  and  Criccieth  will  recognise  excellent 
examples  of  such  shores,  and  doubtless  many  similar  exist  round 
the  coast.  The  boulders  near  low-water  mark  yield  the  richer 
harvest,  and  the  underneath  is  the  surface  to  work.  Where 
two  of  these  huge  boulders  have  fallen  close  together,  so  as  to 
form  a  miniature  tunnel,  the  latter  is  sure  to  afford  a  prolific 
hunting-ground.  My  method  is  to  lie  on  my  back  and  gradually 
work  into  the  tunnel,  carrying  a  blunt  knife  and  some  fair-sized 
bottles,  or  jars,  of  sea-water,     The  surface  of  the  rock  is  chipped, 


PRESERVATION    OF    THE    HYDROIDA.  147 

or  scraped,  where  promising  growth  appears,  and  the  gathering 
dropped  into  the  bottles,  to  be  examined  elsewhere  and  in  a 
more  comfortable  position.  This  is  really  an  excellent  method 
of  obtaining  material. 

Dredging  is  not  likely  to  be  undertaken  by  the  occasional 
collector  unless  he  is  a  very  enthusiastic  one,  and  if  undertaken 
the  individual  will  probably  be  in  no  need  of  advice  from  me,  as 
he  will  know  more  or  less  about  it.  To  the  beginner  I  would 
say,  choose  a  dredge  of  moderate  size  and  confine  dredging 
operations  to  moderate  depths,  i.e.  up  to  ten  fathoms.  If  any 
fishing  industry  is  carried  on  where  the  collector  happens  to  be, 
he  may  get  ample  employment  from  a  bucket  of  trawl  refuse 
obtained  from  one  of  the  boats ;  even  the  rejectamenta  of 
lobster-pots  is  a  good  hunting-ground.  On  an  open  sandy  coast, 
after  a  gale  or  heavy  sea,  deep-water  specimens  may  be  obtained 
in  excellent  condition  if  the  jetsam  left  by  a  receding  tide  is 
carefully  looked  over.  They  should  be  promptly  placed  in  bottles 
of  sea-water,  to  recover  and  expand  their  tentacles,  and  this 
process  may  be  aided  by  vigorously  aerating  the  water  by  means 
of  a  syringe. 

Having  collected  the  material,  the  less  eventful  work  of  pre- 
paring it  for  the  microscope  follows  as  a  matter  of  course,  and 
I  believe  I  am  doing  beginners  a  service  in  urging  upon  them 
the  desirability  of  arranging  for  this  to  take  place  at  the  earliest 
possible  moment  after  collecting.  Once  the  hydroids  begin  to 
feel  the  effects  of  overcrowding  and  badly  aerated  water  the 
polyps  withdraw  into  their  calycles,  and  require  a  large  expendi- 
ture of  time  and  patience  to  coax  them  to  expand  again.  The 
best  results  are  undoubtedly  got  when  the  collector  is  in  a 
position  to  go  straight  from  the  shore  to  his  microscope  and  deal 
with  the  material  collected.  The  polyps  are  then  vigorous  from 
their  normal  environment,  less  intolerant  of  the  narcotising 
agent,  and  a  considerable  quantity  of  material  can  be  dealt  with 
in  a  comparatively  short  time,  as  there  is  no  tedious  waiting 
for  the  polyps  to  expand.  My  own  method  is  to  divide  the 
collection  into  two  lots,  separating  the  Gymnoblastea  from  the 
Calyptoblastea,  as  the  former  can  be  best  prepared  by  killing 
without  the  intervention  of  a  narcotic.  The  hydroids  are  placed 
in  watch-glasses  (or  better  still  small  Petri  dishes)  with  clean 
fresh  sea- water,  and  cleansed  as  far  as  can  be  without  injuring 


148  G.    T.    HARRIS    ON    THE    COLLECTION    AND 

the  polyps  by  gently  brushing  the  polypary  with  a  camel's  hair 
brush.  They  are  allowed  to  recover  from  the  shock,  and  then 
a  few  drops  of  1-per-cent.  cocain  hydrochlorate  added  to  each 
watch-glass  and  the  glasses  set  gently  aside  until  all  the  species 
have  been  dealt  with.  When  the  polyps  are  fresh  and  vigorous 
narcotisation  is  not  a  difficult  process,  nor  one  requiring  extreme 
care,  but  should  the  hydroids  be  left  twenty-four  hours  or  so 
before  dealing  with  them  the  process  is  likely  to  be  not  only 
tedious  but  generally  unsuccessful.  When  the  polypites  are 
judged  to  be  sufficiently  narcotised  to  permit  of  killing  the 
tentacles  should  be  pricked  with  a  needle  somewhat  roughly,  to 
be  quite  certain  that  narcotisation  is  sufficient  to  prevent  retrac- 
tion of  the  tentacles.  I  learnt  by  experience  that  even  when 
insensibility  was  apparently  well  established,  on  the  application 
of  the  killing  and  fixing  agent  the  polypites  would  withdraw  at 
least  partially,  perhaps  wholly,  into  the  calycles,  so  that  it  is 
necessary  to  be  quite  sure  that  narcotisation  is  complete  before 
using  the  fixing  fluid.  The  killing  and  fixing  agent  most  con- 
venient is  undoubtedly  osmic  acid,  either  a  plain  1-per-cent. 
solution  or  combined  with  platinum  chloride  as  in  Hermann's 
solution.  I  have  tried  many  other  solutions  for  this  purpose, 
but  found  none  more  suitable.  The  osmic-acid  solution  is  sprayed 
over  the  colony  in  the  watch-glass  with  a  pipette  and  allowed  to 
act  for  several  minutes,  when  it  is  washed  away  by  repeated 
changes  of  clean  fresh  water,  allowing  the  specimens  to  soak  in 
each  wash  water  for  some  time.  Finally  they  are  given  a 
weak  bath  of  hydrogen  peroxide  or  potassium  ferrocyanide,  to 
thoroughly  eliminate  the  acid,  and  again  well  washed.  This  is 
the  procedure  for  Calyptoblastic  hydroids,  the  Gymnoblastic 
may  have  a  little  more  cavalier  treatment.  If  narcotisation  is 
attempted  with  them  it  has  the  effect  of  causing  them  to 
gradually  shorten  the  tentacles,  and  once  that  has  taken  place 
they  never  extend  them  again  while  under  the  influence  of  the 
narcotic.  This  being  the  case  the  best  method  is  to  kill  them 
suddenly  with  an  energetic  killing  agent  while  fully  expanded. 
Some  retraction  of  the  tentacles  may  take  place  in  the  killing, 
but  to  nothing  like  the  extent  that  would  happen  if  narcotisa- 
tion were  attempted.  It  is  unfortunate  that  mono-bromide  of 
camphor  is  insoluble  in  sea-water,  as  I  am  convinced,  from  the 
admirable  results  it  gives  with  Cordylophora  and  Hydra,  that 


PRESERVATION    OF    THE    HYDROIDA.  149 

it  would  form  an  excellent  narcotiser  for  this  division.  Lang's 
fluid  is  a  good  killing  agent  for  the  Gymnoblastea,  and,  of  course, 
assists  staining  if  carmine  is  used.  Picric  acid  also  answers  well ; 
and  osmic  acid  or  Hermann's  solution  if  the  specimens  are  not 
too  large,  otherwise  I  have  found  the  killing  occupy  sufficient 
time  to  permit  of  considerable  contraction. 

Undoubtedly  the  great  difficulty  in  preparing  hydroids  for  the 
microscope  lies  in  getting  clean  mounts — that  is,  supposing  clean 
mounts  are  desired — and  this  difficulty  becomes  augmented  with 
material  from  between  tide-marks.  The  polyparies  are  generally 
encrusted  and  overgrown  with  an  olla  podrida  of  marine  life,  so 
that  the  mount  really  becomes  a  compound  object.  To  me 
this  is  anything  but  a  drawback,  providing,  of  course,  that  no 
essential  part  of  the  hydroid  is  masked.  On  some  shores,  how- 
ever, the  amount  of  material  collected  is  out  of  all  proportion  to 
its  interest,  and  it  becomes  necessary  to  subject  it  to  a  cleansing 
process.  This  should  be  done  before  narcotising  and  killing  the 
hydroid,  otherwise  the  tentacles  are  liable  to  be  injured  and 
entangled.  The  polyps  withdraw  into  their  calycles  during  the 
application  of  the  brush,  but  soon  recover  from  their  fright  when 
placed  in  a  glass  of  clean  fresh  water  and  allowed  to  rest  quietly 
for  a  time. 

If  staining  and  mounting  fixed  material  are  deferred  until  a 
more  convenient  time,  it  has  to  be  stored  in  some  preservative 
fluid ;  formalin  at  once  suggests  itself,  for  which  reason  I 
wish  to  utter  a  word  of  warning.  Formalin  is  perfectly  satis- 
factory for  objects  that  are  to  be  mounted  unstained,  as  they 
will  eventually  find  a  permanent  home  in  this  medium,  but 
personally  I  have  not  been  successful  in  staining  material  that  has 
been  stored  for  some  months  in  a  5-per-cent.  solution  of  formalin. 
This,  of  course,  may  be  due  to  some  error  peculiar  to  myself,  but 
I  would  offer  this  warning  to  inexperienced  workers.  If  time 
and  facilities  allow  I  would  strongly  advise  the  beginner  to  stain 
straight  away,  and  if  unable  to  mount,  then  store  the  stained 
material  in  70-per-cent.  alcohol.  Tailing  this,  I  think  it  prefer- 
able to  store  those  hydroids  destined  for  staining  in  70-per-cent. 
alcohol.  In  storing  avoid  the  error  of  putting  too  many  into  one 
tube ;  small  tubes  with  a  few  in  each  are  very  much  better  than 
a  heterogeneous  collection  of  species  in  a  large  tube  or  bottle. 

The  microscopist  will  doubtless  have  his  own  pet  stain  or  stains, 


150  G.    T.    HARKIS    ON    THE    COLLECTION    AND 

and  as  a  good  general  stain  is  all  that  is  required  for  systematic 
work  it  does  not  much  matter  which  is  used.  I  have  used 
principally  para-carmine,  carmalum  and  haemalum  of  Mayer's 
formulae;  the  last  of  which  I  prefer  on  account  of  its  better 
visual  properties,  also  because  it  stains  exceptionally  well  objects 
that  have  been  fixed  with  osmic  acid.  I  may  here  mention  that 
haeniatoxylin  has  been  regarded  by  some  workers  as  a  fugitive 
stain ;  why,  I  am  unable  to  discover.  I  attempted  to  bleach 
some  slides  that  had  been  over-stained  by  exposing  them  for  some 
months  in  a  window  with  a  south  aspect,  and  at  the  end  of  that 
time  withdrew  them  as  hopelessly  permanent.  They  should  have 
faded,  according  to  all  the  authorities,  but  much  to  my  disgust 
they  did  not. 

For  unstained  objects  I  use  excavated  slips,  and  a  2^-per-cent. 
solution  of  formalin.  A  ring  of  old,  fairly  thick  gold  size  is  run 
round  the  edge  of  the  hollow  and  allowed  to  become  nearly  dry,  at 
least  dry  enough  to  retain  the  impression  of  a  scratch  made  with 
a  needle.  The  selected  portion  of  the  hydroid  colony  is  placed  in 
the  cell,  and  2|-per-cent.  formalin  solution  added  until  a  full  cell 
with  a  convex  surface  to  the  fluid  is  obtained.  The  cover-glass  is 
then  placed  in  position,  expelling  the  superfluous  formalin.  Under 
a  mounting  microscope,  with  a  strong  blunt  needle,  the  cover- 
glass  is  pressed  into  intimate  contact  with  the  ring  of  gold  size, 
until  it  can  be  seen  that  no  lacunae  exist  between  it  and  the  cover- 
glass.  The  extraneous  formalin  is  now  removed  and  the  slide 
allowed  to  dry,  when  several  rings  of  gold  size  may  be  applied. 
Slides  so  prepared  have  attained  the  comparative  antiquity  of 
sixteen  or  eighteen  years  without  showing  any  deterioration. 

As  this  paper  has  been  prepared  with  the  object  of  placing 
practical  information  before  those  desirous  of  devoting  some 
attention  to  our  hydroid  fauna,  it  may  not  be  considered  alien  to 
the  subject  if  I  refer  briefly  to  various  localities  of  which  I  have 
personal  knowledge,  from  collecting  more  or  less  frequently  in 
them ;  merely  premising  that  my  acquaintance  with  them  as 
collecting-grounds  has  been  more  by  accident  than  design,  and  I 
have  no  wish  to  suggest  that  they  are  any  more  desirable  from 
the  collector's  point  of  view  than  numbers  of  others  unknown  to 
me.  In  North  Wales  my  collecting-stations  have  been  Llandudno, 
Menai  Straits,  Criccieth  and  Barmouth.  Llandudno  and  Criccieth 
are  excellent  grounds.     The  rocks  at  I4andud.no  under  the  Great 


PRESERVATION    OF    THE    HYJDROIDA.  151 

Orme  afford  plenty  of  work  at  low  tide,  but  rock-pools  are 
practically  non-existent ;  I  have  taken  many  good  northern 
species  from  the  under-sides  of  the  boulders  strewn  about. 
Criccieth  is  a  capital  ground  ;  the  rocks  on  the  shore  at  the  foot 
of  the  Castle  Hill  repay  the  most  ample  attention,  yielding  many 
and  good  species.  A  short  distance  from  Criccieth  are  the  Black 
Rock  caves,  which  are  really  a  paradise  for  the  shore  collector, 
but  are  only  accessible  at  low  tide.  The  Menai  Straits,  also,  have 
good  collecting-spots  on  the  rocks  at  the  Suspension  and  Tubular 
bridges,  but  the  drawback  to  work  thereabouts  is  the  swiftness  of 
the  tide,  which  makes  boating  difficult  and  risky  unless  accom- 
panied by  a  local  boatman.  Pennington  collected  many  species 
between  the  two  bridges.  Staithes,  in  Yorkshire,  has  a  good 
shore  for  collecting,  as  the  rock-pools  are  ample.  Coming  now  to 
Devonshire,  with  whose  shores  I  have  intimate  acquaintance,  we 
reach  ground  made  classic  by  the  labours  of  Gosse,  Hincks, 
Allman,  Kingsley,  Montagu  and  many  others.  Ilfracombe,  in 
North  Devon,  has  the  advantage  of  clear  rock-pools,  in  places  an 
almost  vertical  rise  and  fall  of  tide,  and  excellent  boating  and 
dredging.  As  it  has  received  its  meed  of  praise  at  the  hands  of 
such  authorities  as  Hincks  and  Gosse,  not  to  mention  Lewes,  it 
may  be  considered  sufficiently  hall-marked.  Torquay,  Gosse's 
home  and  hunting-ground  par  excellence,  is  indubitably  an  ideal 
district ;  I  know  no  better.  The  collecting  at  the  Corbon's  Head 
alone  will  occupy  a  long  holiday,  and  the  coast  under  Livermead, 
Kingsley 's  one-time  residence,  is  honeycombed  with  charming 
rock- pools  full  of  hydroid  life.  At  Brixham  one  gets  in  touch 
with  a  tiawling  district,  and  plenty  of  chances  occur  of  going 
over  trawl  refuse.  In  East  Devon,  from  Exmouth  to  Sidmouth, 
the  naturalist  has  to  set  a  watch  on  his  lips,  for  the  combination 
of  excellent  rock-pools  and  cliffs  of  Keuper  marl  is  more  than  the 
average  shore  collector  can  bear  unmurmuringly.  At  the  same 
time,  the  fauna  of  these  rock-pools  is  both  luxuriant  and  diversi- 
fied ;  and  one  has  to  remember  that  it  was  principally  in  East 
Devon  that  Hincks  collected  both  hydroids  and  Polyzoa. 

I  would  conclude  with  an  apology  for  the  extremely  elementary 
nature  of  this  paper.  It  is  a  mere  account  of  personal  methods, 
offered  to  the  inexperienced  in  the  hope  of  smoothing  away  some 
of  those  preliminary  difficulties  that  appear  to  be  "  commensal " 
with  the  early  days  of  all  new  subjects. 


152  g.  t.  harris  on  the  collection  and 

Notes  on  Some  Species  of  Hydroida,  principally  intended 
for  Purposes  of  Identification. 

Clava  multieomis. 

The  polypites  in  this  species  are  scattered,  not  grouped  as  in 
the  next. 

Clava  squamata. 

Polypites  in  groups,  clustered,  gonophores  in  dense  clusters  at 
base  of  tentacles. 

Clava  cornea. 

Clusters  of  polypites  much  smaller  than  in  C.  squamata,  gono- 
phores smaller  and  less  densely  clustered.  The  two  species  are 
closely  allied,  and  Dr.  T.  S.  Wright  considered  cornea  a  variety 
of  squamata. 

Podocoryne  areolata. 

Apparently  a  rare  species,  as  Hincks  only  records  it  from  three 
localities.  It  is  easily  distinguished  by  the  sessile  gonophores 
being  borne  on  the  chitinous  expansion  of  the  stolon. 

Coryne  vaginata. 

The  common  species  of  the  south  coast,  and  may  be  recognised 
principally  by  the  cup-like  membranous  expansion  of  the  polypary. 
It  is  essentially  a  rock-pool  species. 

Coryne  pusilla. 

In  this  species  the  tentacles  are  "  more  truly  whorled  than  in 
any  other  form  of  Coryne  "  (T.  H.).  The  polypites  are  linear  in 
shape,  and  "of  about  equal  size  from  one  extremity  to  the  other  " 
(T.  H.).  The  only  specimen  I  have  ever  had  was  found  in  some 
material  sent  from  Marazion. 

Eudendrium  ramosum. 

The  height  given  for  this  species  by  Hincks  is  "about 
6  inches,"  but  it  appears  to  become  dwarfed  as  it  nears  a  littoral 
habitat. 

Eudendrium  insigne. 

In  the  absence  of  gonophores  the  specific  name  can  only  be 
given  with   considerable  hesitation.       Hincks  states  its  habitat 


PRESERVATION    OF    THE    HYDROIDA.  153 

"to  be  between  tide  marks  on  the  south  coast,  and  mentions 
a  circular  groove  near  the  base  of  the  body  as  a  means  of 
identification. 

Perigonimus  sessilis. 

The  only  species  with  ringed  coenosarc.  The  polyp  not  dilated 
underneath  the  tentacles. 

Bougainvillea  muscus. 

Allman  distinguishes  this  species  by  its  small,  habit  and  the 
fact  that  its  stems  consist  of  a  single  tube,  instead  of  being 
composed  of  several  tubes  coalesced  into  one.  The  records  for 
this  species  seem  to  be  very  scanty. 

Clytia  Johnstoni. 

The  pedicel  in  this  species  is  usually  ringed  at  the  top  and  at 
the  bottom,  being  smooth  in  the  middle  portion.  Some  specimens 
are,  however,  more  or  less  ringed  throughout. 

Obelia  geniculata. 

This  species  is  readily  distinguished  by  the  projections  sup- 
porting the  ringed  pedicels  bearing  the  hydrotheca. 

Campanularia  neglecta. 

The  margin  of  the  calycle  in  this  species  is  crenulate.  This 
■can  only  be  seen  with  difficulty,  as  it  is  so  readily  damaged. 

Halecium  Beanii. 

It  may  be  easily  identified  when  bearing  female  capsules  by 
their  distinctive  shape  and  the  short  tubular  orifice  in  the  middle 
of  the  capsule. 

Sertularia  filicula. 

This  hydroid  varies  in  the  position  of  the  calvcles  on  the  stem, 
some  being  placed  oppositely,  and  some  more  or  less  alternately. 
It  may  be  distinguished  by  the  single  erect  calycle  in  the  axils 
of  the  branches.  It  is  a  deep-water  species  (20  fathoms),  and 
more  especially  a  northern  species.  Hincks  never  met  with  it 
in  Devon  or  Cornwall,  so  its  occurrence  in  rock-pools  at  Sidmouth 
is  somewhat  noteworthy. 

Jourx.  Q.  M.  C,  Series  II.— No.  73.  11 


154    G.  T.  HARRIS,  COLLECTION  AND  PRESERVATION  OF  THE  HYDROIDA_ 

Plumularia  pirmata. 

The  Plumulariidae  are  somewhat  difficult  for  the  beginner  to> 
separate,  owing  to  the  superficial  resemblance  of  one  species  with 
another.  The  most -trustworthy  means  of  separating  the  species 
is  by  a  careful  observance  of  the  nematophores  and  distances  of 
the  calycles.  In  P.  pinnata  the  nematophores  are  very  minute, 
and  lack  the  pronounced  calycle  present  in  other  species,  and. 
are  one  below  each  hydrotheca.  The  gonothecae  also,  when 
present,  help  materially  in  distinguishing  the  various  species. 
In  the  present  species  they  are  ovate,  with  spinous  projections 
on  the  top. 

Plumularia  setacea. 

It  somewhat  resembles  the  former  species,  but  the  nema- 
tophores are  very  different,  being  of  superior  size  and  differing  in 
number.  The  gonothecae  are  quite  different,  being  flask-shaped  ; 
their  axillary  position  also  is  an  aid  to  diagnosis. 

Plumularia  echinulata. 

In  this  species  the  pinnae  have  an  unmistakable  arched  form 
which  does  not  occur  in  the  others.  The  nematophores  are 
smaller  than  in  P.  setacea,  and  one  nearly  always  occurs  in  the 
axils  of  the  pinnae.  The  gonothecae,  however,  when  present 
readily  determine  the  species. 

Plumularia  similis. 

This  appears  to  be  very  near  the  former  species  (P.  echinulata), 
but  the  gonothecae  are  totally  dissimilar,  being  without  the 
spinous  projections. 

Plumularia  halecoides. 

A  minute  species,  and  easily  overlooked,  The  polypites  have- 
been  compared  to  an  hour-glass  in  shape.  The  gonothecae  are 
transversely  ribbed.  Nematophores  very  minute  and  difficult  to 
detect. 

[The  above  notes  are  intended  for  use  with  a  series  of  slides 
presented  to  the  Cabinet  by  Mr.  G.  T.  Harris.] 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  73,  November  1913. 


155 


THE  MINUTE  STRUCTURE  OF  COSCINODISCUS  ASTER. 
OMPHALUS  AND  OF  THE  TWO  SPECIES  OF 
PLEUROSIGMA,     P.    ANGULATUM  AND    P.    BALTICUM 

By  T.  A.  O'Donohoe. 

{Read  May  28th,  1913.) 

Plate  14. 

In  preparing  this  paper  it  was,  at  first,  my  intention  to  refer  in 
no  way  to  the  work  of  others,  of  which,  in  fact,  I  had  very  little 
knowledge.  It  has,  however,  been  pointed  out  to  me  that  it  is 
desirable  to  mention  previous  researches,  in  order  to  enable  the 
reader  to  compare  these  more  easily  with  my  own.  Happily 
Mr.  E.  M.  Nelson  gives  a  brief  summary  of  his  work  on  the 
valve  of  Pleurosigma  in  a  note  read  at  the  Club  on  January 
28th,  1913  (Journ.  Q.  M.  C,  vol  xii.,  p.  98).  This  note  is 
therefore  easily  accessible  to  all  my  readers,  and  any  further 
reference  to  it  by  me  would  be  unnecessary.  I  regret  I  cannot 
so  easily  dispose  of  the  observations  of  Mr.  T.  F.  Smith,  who 
has  for  many  years  devoted  much  time  and  thought  to  the 
structure  of  diatoms,  and  who  has  so  recently  as  August  1911 
and  October  1912  contributed  to  Knowledge  two  papers  on  this 
much-discussed  subject,  entitled  "  The  True  Structure  of  the 
Diatom  Valve."  These  papers  contain  very  many  photo- 
micrographs, of  which  several  are  excellent.  I  very  much 
regret,  however,  that  I  cannot  agree  with  what  I  must  call 
his  heterodox  views.  In  his  own  words,  "The  points  desired  to 
be  driven  home  in  the  present  article  are  that  diatom  structure, 
consists  of  neither  beads  nor  perforations  as  commonly  under- 
stood"  (page  291). 

Speaking  of  Pleurosigma  for mosum,  he  says:  "  It  appears  to 
consist  of  a  series  of  chains,  as  it  w-ere,  formed  of  short  bars  or 
fibrils  of  silex,  arranged  lengthways  on  the  valve.  They  run  in 
pairs,  parallel,  each  pair  having  larger  and  narrower  interspaces 
between  them  in  regular  succession,  and  so  placed  that  the  larger 
interspaces  are  set  obliquely  to  the  corresponding  interspaces 
between  the  other  pairs  both  above  and  below."  A  few  lines 
farther  on  he  tells  us  that  "  his  theory  is  this,  that  what  we  see 
in  the  Pleurosigma  valve  when  sound  is  not  the  structure  at 
all,  but  simply  a  collection  of  focal  images  thrown  from  the  other 


156  T.   a.  o'donohoe  on  the  minute 

layer  upon  the  one  nearest  the  eye,  just  as  a  picture  is  thrown 
from  the  optical  lantern  upon  a  canvas  screen.  The  fibrils  or 
grating  is  the  real  structure,  of  which  the  texture  is  concealed, 
•even  as  that  of  the  canvas  screen  is  concealed  by  the  picture." 
So  much  for  this  new  theory.  We  can  consider  only  a  few  of 
its  points.  The  figures  given  on  page  289  are,  we  are  told, 
photomicrographs  of  the  two  separated  membranes  of  a  valve  of 
Pleurosigma  angulatum.  If  two  really  good  photographs  were 
taken  of  these  two  membranes  at  about  4,000  diameters,  they 
would,  in  my  opinion,  make  an  end  of  Mr.  Smith's  theory,  but 
instead  of  giving  his  readers  two  such  images,  which  would  be 
extremely  interesting  and  valuable,  he  gives  them  a  great 
number  of  outers  ides  and  innersides  which,  he  tells  us,  do  not 
show  the  structure  at  all,  and  are  therefore  of  very  little  value. 
Indeed,  I  may  say  for  myself  that  I  attach  little  or  no  value  to 
interpretations  of  fine  diatomic  structure  other  than  those  of 
thoroughly  separated  single  membranes.  Of  these  only  can  we 
speak  with  a  fair  degree  of  certainty. 

Turning  now  to  page  331,  we  find  that  Mr.  Smith  says  :  "  Fig. 
14  is  from  an  innerside  of  another  valve  (of  P.  formosum),  the 
first  ever  seen  and  taken,  showing  the  fracture  through  un- 
doubted perforations,"  and  Mr.  Nelson,  being  called  to  his  aid, 
testifies  that  "  Mr.  Smith  has  found  this  fracture,  had  shown  it 
to  him,  and  that  at  any  rate  the  fracture  did  run  through  the 
holes."  So,  too,  Mr.  Smith  cites  the  testimony  of  Dr.  Dallinger, 
who  says  :  "  In  Plate  I.  fig.  1  (Carpenter  on  the  Microscope)  we 
have  a  photograph  of  his  showing  the  inside  of  a  valve  of 
Pleurosigma  angulatum  magnified  1,750  diameters,  exhibiting 
the  "  postage-stamp  fracture."  The  postage-stamp  fracture  is, 
as  everybody  knows,  a  fracture  through  the  holes,  so  that  we 
have  these  two  great  authorities  testifying  to  the  fact  that  these 
photographs  of  Mr.  Smith  show  fractures  through  holes,  or,  as 
Mr.  Smith  calls  them,  undoubted  perforations.  His  theory  being 
that  there  are  neither  holes  nor  beads  in  the  valve  of  a 
Pleurosigma,  does  he  now  repudiate  these  photographs  and 
these  testimonies'?  He  speaks  of  his  fibrils  forming  interspaces, 
chains  and  gratings,  and  it  would  be  interesting  to  have  his 
definitions  of  these  terms.  Can  there  be  chains  or  gratings 
without  intervening  spaces,  i.e.  holes  or  perforations  ? 

Fig.  18,  page  333,  "  The   innerside   of  Pleurosigma  angulatum 

X  3,770,"  by  no  means   a  sharp  image,  shows,  nevertheless,  holes 

galore   to  any   one  who   is  not   blind  or  unwilling  to  see  them. 


STRUCTURE    OF    C0SC1N0DISCUS   AsTEROMPHALUS,    ETC.  157 

Mr.  Smith's  second   paper   (October  1912)  I   cannot   touch  :  the 
exigencies  of  space  forbid. 

I  am  indebted  to  two  members  of  the  Club  for  the  loan  of  two 
slides — realgar  mounts — which  have  enabled  me  to  study  the 
minute  structure  of  Pleurosigma  angulatum  and  Pleurosigma 
balticiua.  Having  taken  several  photographs  from  a  slide  lent 
me  by  my  friend  Mr.  Bruce  Capell,  I  showed  some  of  them  to 
our  Secretary  and  Editor,  and  the  latter  informed  me  that 
Mr.  Nelson  was  engaged  more  or  less  on  the  same  subject,  and 
suggested  that  I  should  send  him  copies  of  my  photographs. 
This  suggestion  I  fell  in  with  the  more  readily  inasmuch  as  it 
would  give  me  the  benefit  of  any  adverse  criticism  which  Mr. 
Nelson  might  feel  himself  called  upon  to  make.  To  elicit  this  I 
wrote  on  the  back  of  each  a  brief  interpretation  of  the  structure, 
and  in  one  case  in  which  I  was  much  puzzled  I  placed  a  note  of 
interrogation.  With  his  usual  kindness  and  urbanity,  Mr.  Nelson 
gave  the  desired  information,  but  instead  of  adverse  criticism  he 
sent  me  two  slides  of  great  historic  as  well  as  intrinsic  value. 
From  these  I  have  been  enabled  to  make  some  photographs 
which  confirm  the  results  already  obtained  from  the  slide  belong- 
ing to  Mr.  Bruce  Capell. 

Coming  now  to  my  immediate  subject,  my  readers  are,  no 
doubt,  aware  that  Dr.  Van  Heurck  tells  us  that  a  diatom  valve 
consists  of  two  membranes  and  of  an  intermediate  laver  which  he 
calls  a  septum,  and  that  it  is  this  latter  layer  which  contains  the 
cavities  or  perforations.  In  my  opinion  this  definition  connotes 
at  once  too  much  and  too  little  :  too  much  by  giving  the  valve 
three  layers,  and  too  little  by  confining  the  cavities  to  the  septum 
only.  In  the  three  valves  which  we  are  about  to  consider,  I  find 
only  two  layers  or  membranes,  each  of  which  has  its  own  perfora- 
tions. We  will,  in  the  first  place,  consider  the  structure  of 
C oscinodiscus  asteromphalus.  The  photographs  are  taken  from 
some  of  my  own  mounts  in  styrax.  Of  course  I  am  aware  that 
this  valve  was  very  ably  and  fully  treated  recently  elsewhere  by 
Dr.  Butcher  (Journ.  R.  M.  S.  1911,  p.  722),  but  my  chief  object 
in  bringing  it  before  you  now  is  to  determine,  if  we  can,  which  is 
the  correct  image,  the  black  dot  or  the  white  dot.  [Here  Mr. 
O'Donohoe  illustrated  his  remarks  by  photographs  projected  on 
the  screen.]  The  black-  and  white-dot  images  now  thrown  on  the 
screen  have  been  taken  direct  at  a  magnification  of  4,000 
diameters,  and  to  my  mind  it  seems  perfectly  obvious  that  two 
images   so   utterly  unlike    one    another    cannot   both   be  correct 


158  T.  a.  o'donohoe  on  the  minute 

representations  of  the  same  structure.  The  next  two  slides  show 
the  inner  membrane  projecting  beyond  the  outer  one,  and  on 
examining  the  edge  of  the  fracture  it  becomes  at  once  evident 
that  what  is  called  the  eye-spot  is  a  comparatively  large 
perforation.  This  membrane  also  shows  considerable  thickness. 
I  have  been  able  to  find  a  small  fragment  in  which  the  outer 
membrane  projects  a  little  beyond  the  inner  layer.  This  is  seen 
by  the  fact  that  the  silex  of  the  projecting  part  appears  white. 
It  should  now  be  noted  that  this  white  silex  is  sharply  defined  at 
the  edge,  that  this  edge  shows  hardly  any  thickness,  and  that  the 
perforations  are  represented  by  black  dots.  The  next  image  has 
been  obtained  by  making  no  other  alteration  than  that  of  raising 
the  objective  until  the  white  dots  appeared.  On  examining  this 
image  we  find  the  white  silex  has  become  black,  and  the  edge  of 
the  fracture  which  was  so  well  defined  in  the  black-dot  picture  is 
now  so  blurred  and  fogged  as  to  have  become  invisible.  We  have 
next  two  fragments  of  Pleurosigma  angulatum  in  juxtaposition, 
showing  respectively  the  black  and  white  dots.  The  black  dot 
image  gives  the  "postage-stamp"  fracture  well  defined  in  white 
silex,  whereas  the  broken  edge  in  the  other  fragment  is  black, 
out  of  focus  and  blurred.  We  are  therefore  justified,  I  think, 
in  relegating  the  white-dot  images  of  diatom  structure  to  the 
abode  of  Mr.  Nelson's  ghosts.  Here,  methinks,  I  hear  the  tyro 
in  microscopy  cry  out,  "  If  that  be  so,  why  do  we  meet  with 
so  many  white-dot  images  in  the  books  which  are  written  for 
our  guidance  ? "  I  prefer  to  let  the  writers  of  these  books 
answer  for  themselves.  Mr.  Pringle,  in  Practical  Photomicro- 
graphy, 1890,  page  173,  writes:  "In  spite  of  all  these  details, 
A.  pellucida  is  child's  play  to  photograph  in  comparison  with 
such  tests  as  Pleurosigma  angulatum,  Surirella  gemma  and 
Navicula  rhomboides  by  axial  light  and  to  show  '  black  dots. 
Pleurosigma  angulatum  in  white  areoles,  or  Navicula  rhomboides 
in  squares,  with  a  special  disc  in  the  condenser,  is  infinitely 
easier  than  the  same  in  black  dots." 

Let  us  turn  now  to  Plates  III.  and  IV.  of  Dr.  Spitta's  Photo- 
micrography (1899).  What  do  we  find?  White-dot  images  of 
all  his  diatomic  tests.  Not  one  black-dot  image  !  He  has,  no 
doubt,  some  good  reason  for  this,  and  turning  to  page  138  we 
find  it.  Writing  about  the  photography  of  Pleurosigma 
angulatum,  Dr.  Spitta  says :  "  It  has  two  principal  planes  of 
focus,  and  much  difference  of  opinion  exists  as  to  which  is  the 
correct  one.     The  last  picture  taken  by  Dr.  Van  Heurck  with 


STRUCTURE    OF    COSCINODISCUS  ASTEROMPHALUS,    ETC.  159 

the  new  Zeiss  N.A.  1*6  objective,  and  the  attendant  para- 
phernalia, seems  to  show  that  after  all  the  black  dot  is  more 
^correct  than  the  white  one.  As  before  stated,  the  white  one 
is  the  easiest  to  photograph,  for  the  black  dot  seems  never  to 
be  sufficiently  defined  to  look  as  sharp  as  we  should  like  it." 

For  the  sake  of   the  aforesaid   tyro  I  will  here   quote  a  little 
advice  which  Mr.   Nelson    gave    me    eight    years  ago  (I  began 
photomicrography  very  late  in  life)  on  the  white  dot.     Among 
several  black-dot  photographs  which  I  sent  him,  and  which  he 
was    kind    enough    to    praise,  there    was    a    white-dot    Isthmia 
nervosa  of  which  he  said  :   ':  I  think  the  Isthmia  would  be  better 
with    black-dot  focus ;    this  white-dot    focus    is    an    out-of -focus 
ghost.      It  is  much  easier  to  get  than  a  correct  picture,  and  on 
that    account     it    seems    to    be    a    favourite    with    some    photo- 
graphers ;  but  any  one  really  interested  in  the  work  should  aim 
At    something    higher.     Of  course,   with  very   fine  structures,  a 
white  dot  is  all  that  can  be  obtained  with  our  present  lenses." 
I  thought    then,  and    still     think,  that    this    was    the    kind  of 
mentor   who   would  always    command  and   receive    the    highest 
respect. 

We  come  now  to  Pleurosigma  angulatum,  of  which  a  black-dot 
image  x  3,700  is  thrown  on  the  screen.  The  next  picture  on  the 
screen  shows  a  fractured  valve  which  has  been  denuded  of  a  part 
of  its  outer  membrane.  The  next  image  shows  this  outer  mem- 
brane x  2,000  broken  up  into  fragments  so  minute  that  the 
particles  of  silex  have  in  some  instances  only  one,  two,  three  or 
four  holes  shown  as  black  round  dots  ;  this  outer  membrane  is  so 
thin  that  the  silex  is  almost  invisible,  and  in  this  respect  differs 
very  much  from  the  inner  membrane,  whose  image  x  2,000  is 
now  thrown  on  the  screen.  I  do  not,  however,  discern  any 
difference  between  the  holes  in  the  two  membranes. 

Finally,  we  have  to  consider  the  structure  of  Pleurosigma 
balticum.  This,  because  of  its  convexity  and  thickness,  is  difficult 
to  photograph,  and  yet  more  difficult  to  understand.  I  am 
illustrating  its  structure  by  showing  you  fifteen  different  photo- 
graphs, each  of  which  I  must  describe  very  briefly ;  but  before 
doing  so,  let  me  define  the  word  "  fibril  "  :  a  fine  filament  of  silex 
which  contains  holes  in  a  row  like  a  string  of  beads ;  it  may 
be  long  or  short.  This  definition  differs  altogether  from  that 
which  Mr.  T.  F.  Smith  gives   to   the  same  word. 

The  first  slide  shows  the  ordinary  valve  with  Van  Heurck's 
■canaliculi  x  1,500. 


160       T.    A.    O'DONOHOE    ON    COSCINOD1SCUS  ASTEROMPHALUS,    ETC. 

The  second  slide  shows  the  round  black  clots  of  the  inner 
membrane  near  the  nodule,  where  the  outer  membrane  has  been 
rubbed  off  (PI.  14,  fig.  1).  The  third  slide  shows  an  impression 
of  the  greater  part  of  a  valve  caused  by  the  adhesion  of  the  outer 
membrane  to  the  slip. 

The  fourth  slide  shows  a  similar  adhesion  to  the  cover-glass, 
as  well  as  the  valve  from  which  the  outer  membrane  was  torn. 
The  fifth  shows  the  same  x  1,000. 

The  sixth  slide  shows  fine  hair-like  bent  fibrils  breaking  away 
from  the  valve. 

The  seventh  shows  a  part  of  the  same  valve  x  2,000,  on  which 
four  fibrils  of  the  inner  membrane  are  visible. 

The  eighth  is  an  image  which  puzzled  me,  and  Mr.  Nelson 
kindly  explained  it  thus  :  "  This  shows  an  upper  bar  crossing  a 
hole.  It  also  shows  the  transverse  girder  work  wonderfully 
clearly"  (PI.  14,  fig.  2).  The  ninth  slide  shows  the  structure  of 
the  inner  membrane  to  be  similar  to  the  last,  but  this  and  the 
three  next  following  photographs  were  taken  from  Mr.  Nelson's 
slide. 

The  tenth  shows  the  outer  membrane  breaking  up  into  fibrils, 
and  sometimes  even  into  isolated  clots  (PI.  14,  fig.  3). 

The  eleventh  and  twelfth  show  continuations  of  the  tenth. 
The  thirteenth  shows  the  structure  of  the  fibrils  very  well  (PI.  14, 
fig.  4).  The  fourteenth  and  fifteenth  show  the  kind  of  structure 
which  is  incorrectly  taken  for  squares,  but  a  glance  at  one  of 
the  single  fibrils  causes  the  optical  illusion  to  vanish. 

In  Pleurosigma  balticum  the  fibrils  run  parallel  with  the  raphe, 
whereas  in  Pleurosigma  angtdatum  they  seem  to  run  obliquely  to 
the  raphe,  and  this,  it  seems  to  me,  is  the  chief  difference  in  the 
minute  structure  of  the  two  valves. 

Description  of  Plate  14. 

Fig.  1.  P.  balticum,  X  1,750.  Showing  the  structure  of  the 
inner  membrane  when  the  outer  has  been  rubbed  off. 

,,  2.  P.  balticum,  x  2,000.  Inner  membrane,  showing  the 
holes  crossed  by  very  fine  bars  of  silex. 

„  3.  P.  balticum,  x  2,000.  Fibrils,  photographed  from  Mr. 
Nelson's  slide. 

,,     4.     P.  balticum,  x  1,250.     Fibrils. 

Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  73,  November  1912. 


Journ.  Q.M.C. 


Ser.  2,   Vol.  XII  ,  PI.  14 


1 

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Fig.  1. 


Fig.  3. 


Fig-. 


Fig.  2. 
Photomicrogr.  T.  A.  OD. 

Structure  of  Pleurosigma  balticum. 


1G1 


LAGENAE    OF    THE    SOUTH-WEST    PACIFIC    OCEAN.. 

(SUPPLEMENTARY   PAPER.) 
By  Henry  Sidebottom. 

{Read  June  24/7/,  1913.) 
Plates  15-18. 

INTRODUCTION. 

The  Lagenae  dealt  with  in  this  supplementary  paper  were- 
arranged  by  the  late  Mr.  Thornhill  on  nine  slides,  each  of  which 
is  divided  into  one  hundred  squares.  Nearly  every  square  is 
occupied,  with  the  exception  of  some  on  the  last  slide.  The 
number  of  specimens  exceeds  twelve  thousand.  In  the  material 
for  mv  first  paper  the  number  of  specimens  of  Lagenae  exceeded 
six  thousand,  thus  making  a  grand  total  of  over  eighteen  thousand. 
For  reasons  stated  in  my  former  Introduction,  it  has  not  always 
been  possible  to  give  the  locality  at  which  specimens  were  found. 

The  series  dealt  with  now  is  on  three  sets  of  slides,  Nos.  1-4  A 
being  Penguin  gatherings,  Nos.  1-3  b  Penguin  and  Dart  gatherings 
combined  and  Nos.  1,2  c  those  on  which  Mr.  Thornhill  had  just 
begun  to  bring  together  specimens  arranged  according  to  a  system 
he  had  hoped  to  carry  out. 

The  specimens  of  Lagenae  on  the  three  sets  of  slides  were  not 
arranged  in  sequence  with  each  other,  so  that  the  work  has 
proved  more  laborious  than  that  of  my  first  report. 

The  division  of  the  keel,  which  occurs  in  a  good  many  tests 
and  in  more  than  one  species,  adds  to  the  difficulty  of  identifica- 
tion, and  it  is  easy  to  be  misled  by  it.  The  same  may  be  said 
of  some  of  the  markings  on  the  faces  of  the  test,  which  have 
hitherto  been  considered  as  specific  characters. 

Again  I  must  acknowledge  the  kindness  of  Mr.  Millett,  whose 
advice  I  have  always  found  most  valuable  and  freely  given.  My 
thanks  are  due  to  Mr.  Wright,  of  Belfast,  to  Prof.  Hickson, 
of  the  University  of  Manchester,  for  kind  assistance,  and  also 
to  Mr.  Earland  for  bringing  these  papers  before  the  Quekett 
Microscopical  Club  and  examining  specimens  for  me  in  order  to- 


162    HENRY    SIDEBOTTOM    ON    LAGENAE    OF   THE    SOUTH-WEST    PACIFIC. 

find  out  the  nature  of  certain  markings.  Lastly,  as  regards  the 
text,  I  wish  to  acknowledge  my  indebtedness  to  my  wife  for  her 
assistance  in  rendering  my  descriptions  more  concise. 


H.M.S.  "  Penguin."     S.W.  Pacific.     1897. 


No. 

Statioi 

1. 

939. 

2. 

940. 

3. 

941. 

4. 

943. 

5. 

945. 

6. 

947. 

7. 

949. 

8. 

952. 

9. 

954. 

10. 

955. 

11. 

956. 

23. 


f  2] 
U7i 


Lat.  &  Long. 

f  18-29'  S. 
\  178-38'  E. 
/  18-57'  S. 
U  79-04' 
/   18-43' 

U  78-51' 
/  19-21' 
(.179-30' 

21-47' 
179-25' 
/  22-49' 
\  179-20' 
/  23-44' 
\  179-09' 
/  25-52' 
\  178-47'  E. 

f    26-57'    8. 
1 178-35' 

f  27-46' 
\  178-29' 

/  29-17' 
i  177-17' 


E. 

8. 
E. 

S. 
E. 

S. 
E. 

S. 
E. 

S. 
E. 

S. 


E. 

S. 
E. 

8. 
E. 


H.M.S.  "Pen 


No.        Station. 


4. 


24. 


12. 


18. 


21. 


24. 


25. 


27. 


Lat. 

r  33- 

\157- 

r  33- 

\158- 
/  33- 

U60- 

f  33- 
\161- 

/  33- 

\162- 

f   33 
(163 

/  33- 
V163- 

f   33- 
U64 

/  33- 
\164 

f   34 

\165- 


&  Long. 


53'    S. 

29'  E. 

50'    8. 

47'  E. 

48'    8. 

2'     E. 

56'    S. 

13'   E. 

56' 7" 

S 

33' 

E 

56'  6" 

S 

20' 

E 

57'    8. 

•56'  E. 

58'    S. 

•37'   E. 

■58'  5" 

S 

•55' 

E 

0'  6" 

S 

37' 

E 

GUIN. 

Fms. 

2,578. 
2,338. 
1.190. 

98S. 

498. 

575. 

603. 
1,073. 
1,653. 
1.676. 


Fms. 

No. 

1,122. 

12. 

1,092. 

13. 

1,360. 

14. 

1,420. 

15. 

2,043. 

16. 

1,948. 

17. 

1,903. 

18. 

2,183. 

19. 

2,318. 

20. 

1,803. 

21. 

2,050. 

22. 

Station. 
959. 

961. 

964. 

974. 

975. 

976. 

986. 

987. 

996. 

998. 

1,003. 


Lat.  &  Long. 

f  31-39'  S. 
\  176-49'  E. 

/  33-00'  8. 

\176-16'  E. 

/   34-52'  8. 

(175-34'  E. 

f  35-01'  S. 
\171-37'   E. 

f  35-23'  S. 
1 170-34'  E. 
/  36-09'    S. 

^  169-20'   E. 

f  36-30'  S. 
\168-11'   E. 

f  37-10'  S. 
1 166-30'  E. 

/  37-47'  S. 
\  164-40'  E. 

f   38-24'  S. 

1 163-15'  E. 

/  4305'  8. 

(148-39'  E. 


S.W.  Pacific.     1898. 


No. 


25. 1 


Station. 
35. 

41. 

44. 

75. 


26. 


I 


27. 


28. 


83. 
85. 
86. 
87. 


Lat.  &  Long. 

/  34-19'  8. 

\168-6'  E. 

/  34-20'  S. 

\  168-28'  E. 

/   34-22'  8. 

\17019'  E. 

f  36-21'  8. 

\176-44'  E. 

f  36-3'  S. 

\  17855'  E. 

/  34-33'  S. 

\.  178-15'  W. 


f  32-56'    S. 
\  176-49'  W. 

S. 

w. 

/  31-28'    S. 
{ 171-5'    W. 


/  3216' 
\175-54' 


Fms. 
2,210. 

2,086. 

917. 

796. 

994. 
1,298. 
1,207. 

822. 

735. 
2,182. 
1,611. 


Fms. 

828. 

1,191. 
979. 

832. 
1,389. 

4,278. 

3,360. 
3,220. 
3,100. 


HENRY   SIDEBOTTOM    ON    LAGENAE   OF   THE    SOUTH-WEST   PACIFIC.     163 


No" 

Station 

29. 

93. 

90. 

^in 

94. 

ou.- 

95. 

96. 

31. 

98. 

32. 

143. 

No. 

37. 

38. 


39. 


40. 


Station. 
140. 

70. 

181. 

182. 

188. 

191. 

192. 

393. 

429. 

480. 


Lat.  &  Long. 

Fins. 

f  26-38'    s. 
\17417'  W. 

2,420. 

f   2917'    S. 
\  175-11'  W. 

3,105. 

/  25-53'    S. 
U"46'    W. 

2,775. 

f   23-24'    S. 
\  173-40'  W. 

3,205. 

f   22-14'    S. 
1 17329'  W. 

3,420. 

/  21-8'      S. 
\  174-7'    W. 

2,115. 

f  23-15'    8. 
\175-32'   E. 

2,351. 
1 

H.M.S.  " 

Penguin 

Lat.  &  Long. 

Fms. 

f    10-57'     S. 
\162-21'   E. 

508. 

f  23-17'    8. 
\  154-33'   E. 

470. 

/  11-42'    8. 
U75-51'  W. 

2,335. 

f   11-09'    8. 
\  175  -36'  W. 

1,992. 

f     9-41'    S. 
\  174-37'  W. 

2,290. 

/      8-57'    8. 
V 174-03'  W. 

2,606. 

f     8-36'    S. 
\  173-51'  W. 

2,712. 

/     3-51'   N. 
\  164-13'  W. 

2,330. 

/     4-55'   N. 
\  160-54'  W. 

1,701. 

/      5-10'  N. 
\  160-15'  W. 

2,033. 

No.       Station. 


f 


33. 


34. 


35. 


36. 


14S. 


149. 


151. 


156. 


157. 


167. 


169. 


172. 


Lat.  <fc  Long. 

f  261'  8. 

\  172-56'  E. 

f  26-38'  8. 

\172-26'  E. 

/  27-55'  8. 

\171-22'  E. 

f   29-35'  8. 

\  168-51'  E. 

f   29-42'  8. 
\  168-51' 
/   30-29' 
\  166-16' 

f  30-57' 
\  160-52' 

T  31-18' 
\  163-46' 


E. 

8. 
E. 
8. 
E. 
8. 
E. 


S.W.  Pacific. 


No. 


40. 


41.x 


Station. 
482. 

487. 

488. 

498. 

499. 
502. 
503. 
505. 
506. 


Lat.  &  Long. 

/     6-15'  N. 
\  160-36'  W. 

/      7-25'   N. 
\  160-59'  W. 

f     7-47'  N. 
\  160-45'  W. 

/     8-47'   X. 
\  159-45'  W. 

f     904'  N. 
\  159-32'  W. 

/     9-43'   N. 
\  159-07'  W. 

f   1004'  N. 
1 158-53'  W. 

f    10-43'  N. 
\  158-30'  W. 

/   11-01'  N. 
X 158-21'  W. 


Fms. 
2,428. 

2,070. 

1,632. 

1,269. 

1,446. 

1,819. 

1,557. 

1,010. 


Fms. 

1,861. 
2,501. 
2,573. 
2,588. 

2,579. 
2,758. 

2,800. 
2,938. 
2,863. 


Ko.        Station. 

f 

No  date 

42. 


Lat.  k.  Long. 

2415'    8. 
E. 

S. 
E. 

/  24-36'    8. 
\15332'   E. 


/   24- 1 
\153-1 
/  24-34' 
\  153-32' 


H.M.S.  "Dart." 

Fms. 
328. 

478. 

392. 


No.        Station.      Lat.  <fc  Long. 

Fms 

d,  /        19.      f  29-22'    S. 
^■\(14.5.97.)\153-51'   E. 

465 

44.{(16.1.97.){1^;   £ 

481 

164    HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC. 

Family  LAGENIDAE. 

Sub-family  Lageninae. 

Lagena  Walker  and  Boys. 

Lagena  globosa  Montagu  sp.  (PI.  15,  figs.  1-3). 

Serpula  (Lagena)  laevis  globosa  Walker  and  Boys,  1784,  Test.  Min.r 

p.  3,  pi.  1,  fig.  8. 
Vermiculum  globosam  Montagu,  1803,  Test.  Brit.,  p.  523. 

Very  numerous  and  of  varying  size  and  shape.  The  orifice 
and  internal  tube  are  subject  to  great  variation. — Locality  : 
Many  .stations. 

PL  15,  fig.  1.  The  orifice  is  small  and  somewhat  hooded,  and 
the  test  often  inclined  to  be  apiculate. — Locality  :  Many  stations. 
Rare. 

PI.    15,    fig.    2.     An  elongate  variety. — Locality:   Uncertain. 

Only  one  found. 

PI.  15,  fig.  3.  An  interesting  variation,  the  body  of  the  test 
being  partly  clear  and  partly  opaque.  The  curiously  produced,, 
flattened  mouth,  which  appears  to  be  divided  or  pinched  in  at  the 
centre,  points  to  its  being  allied  to  the  one  figured  +  PI.  14,  fig.  2.* 
The  entosolenian  tube  is  absent. — t Locality :  Nos.  21-26,  34,  38, 
42,  44. 

+  P1.  14,  fig.  2. — Locality:  Uncertain. 

+  P1.  14,  fig.  4.  The  slightly  elongated  form  predominates. — 
Locality :  Many  stations,  including  Nos.  6,  8  ;  after  No.  22  only 
at  one  or  two  stations. 

+  P1.  14,  fig.  5.  This  compressed  variety  of  the  above  is  found 
sparingly  at  a  few  stations,  but  tests  that  are  much  more  com- 
pressed, and  pointed  towards  the  aperture,  are  frequent. 

Lagena  globosa  Montagu  sp.  single  and  bilocular  form. 

Lagena  globosa  Montagu  sp.  single  and  bilocular  form,  Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.  380,  pi.  14,  figs.  7,  8,  9. 

Locality :  Many  stations  up  to  No.  19,  also  at  Nos.  33,  43,  44. 

*  The  "4*"  denotes  that  the  reference  is  to  "  Lagenae  of  the  South- 
West  Pacific  Ocean "  (Journal  Quekttt  Microscopical  Club,  1912,  ser.  2, 
vol.  xi.,  pp.  375-434,  pis.  14-21). 

f  The  numbers  throughout  this  paper  refer  to  my  charts  on  pp.  162,  163, 
where  will  be  found  the  official  numbers  of  the  stations,  with  other 
particulars. 


HENRY    SIDEBOTTOM    OX    LAGENAE  OF   THE   SOUTH-WEST    PACIFIC.      165 

Lagena  globosa  Montagu  sp.  var.  maculata  Sidebottom. 

Lagena  globosa   Montagu  sp.  var.  maculata,    Sidebottom,    1912, 
Journ.  Q.M.C.  p.  380,  pi.    14,  figs.   10,  11. 

Locality  :  Nos.  5  9. 

Lagena  globosa  Montagu  sp.  var.  emaciata  Reuss. 

Lagena  emaciata  Reuss,  1862  (1863),  p.  319,  pi.  1,  fig.  9. 
Lagena  globosa  Montagu  sp.   var.   emaciata  (Reuss)  Sidebottom, 
1912,  Journ.  Q.  M.  G.  p.  381,  pi.  14,  figs.  13-15. 

Locality :  Present  at  numerous  stations  throughout  the  series. 

Lagena  apiculata  Reuss  sp.  (PI.  15,  fig.  4). 

Oolina  apiculata  Reuss,  1851,  p.  22,  pi.  1,  fig.  1. 
Lagena  apiculata  Reuss,  1862  (1863),  p.  318,  pi.  1,  figs.  1,  4-8, 
10,   11. 

PI.  15,  fig.  4. — A  large,  solitary  specimen. — Locality  :  No.  15. 

+  P1.  14,  fig.  16.  Always  rare. — Locality  :  At  Nos.  24,  43,  and 
a,  few  other  stations. 

"J" PI.  14,  figs.  17,  18.  Found  at  many  stations. — Locality: 
Chiefly  at  Nos.  2,  24,  42,  44. 

*P1.  14,  figs.  19,  20.  The  tube  in  this  variation  is  very 
delicate,  and  often  lies  broken  inside  the  test. — Locality:  Occurs 
at  very  many  stations. 

Lagena  apiculata  Reuss  sp.  var.  punctulata  Sidebottom. 

Lagena   apiculata   Reuss   sp.    var.   punctulata   Sidebottom,    1912, 
Journ.  Q.M.  C,  p.  382,  pi.  14,  figs.  21-23. 

Locality  :  Nos.  3,  5-11,  41,  43. 

Lagena  longispina  Brady  (PI.  15,  figs.  5,  6). 

Lagena  long ispina  Brady,  1881,  Quart.  Journ.  Micro.  Sci.,  vol.  xxi., 

N.S.,  p.  61. 
Lagena  longispina  Brady,  1884,  p.  454,  pi.  56,  figs.  33,  36  ;  pi.  59, 

figs.  13,  14. 

As  Brady  states  in  the  Challenger  Report,  this  is  simply  a 
variety  of  L.  globosa.  It  is  not  unusual  for  L.  globosa  to  have 
the  base  of  the  test  roughened  or  finely  spinous.     The  larger  of 


166    HENRY    S1DEB0TT0M    ON   LAGENAE   OF   THE   SOUTH-WEST   FACIFICL 

the  two  specimens  figured  is  so  opaque  that  it  is  impossible  to 
say  whether  the  entosolenian  tube  is  present.  —  Locality  :  Nos.  5,, 
7,  9,  39-41,  44. 

Lagena  ovum  Ehrenberg  sp. 

Miliola  ovum   Ehrenberg,    1843,   p.    166;  — 1854,   pi.    23,  fig.   2; 
pi.  27,  fig.  1  ;  pi.  29,  fig.  45. 

Locality :  This  unsatisfactory  form  occurs  at  many  stations, 
but  is  always  rare.      See  remarks  +p.   382. 

Lagena  botelliformis  Brady  (PL  15,  figs.  7,  8). 
Lagena  botelliformis  Brady,  1884,  p.  454,  pi.  56,  tig.  6. 

PI.  15,  fig.  7.  Only  two  specimens  found.  The  orifice  is  phia- 
line,  and  there  is  a  short  internal  tube. — Locality  :  No.  44. 

PL  15,  fig.  8.  This  is  a  very  fine  example  in  the  apiculate- 
condition.      See  also  +PL   14,  fig.  24. — Locality:  No.  12. 

+  P1.  14,  figs.  24,  25. — Locality;  Many  stations. 

**"PL  14,  figs.  26-28. — Locality:  Stations  uncertain. 

Lagena  laevis  Montagu  sp.  (PL  15,  figs.  9,  10). 

Serpula  (Lagena)  laevis  ovalis  Walker  and  Boys,  1784,  p.  3,  pi.  1,. 

fig.  9. 
Lagena  laevis  (Walker  and  Jacob)  Williamson,  1848,  p.  12,  pi.  1, 

figs.  1,  2. 

L,  laevis  occurs  frequently  in  these  gatherings,  and  the  form 
of  the  test,  the  decoration  of  the  neck  and  the  position  of  the- 
internal  tube  varies.  Some  are  apiculate.  In  a  few  instances 
there  is  an  entosolenian  tube  situated  at  the  base. — Locality  .- 
Many  stations. 

PL  15,  fig.  9.  The  tests  are  semi-opaque,  the  short  neck  is- 
decorated  and  the  internal  tube  straight.  In  several  instances 
fine  spines  project  at  the  base. — Locality :  Nos.  1,  2,  3,  and  one- 
or  two  others. 

PL  15,  fig.  10.  This  appears  to  be  a  smaller  variety  of  the- 
above.  The  tests  are  too  opaque  for  me  to  make  out  whether 
the  entosolenian  tube  is  present.  Some  are  apiculate  and  may- 
be L.  laevis  var.  distoma  Silvestri. — Locality :  At  a  good  many 
stations  throughout  the  series. 


HENRY   SIDEBOTTOM    ON   LAGEXAE    OF   THE   SOUTH-WEST   PACIFIC.     167 

Lagena  laevis  Montagu  sp.  var.  distoma  Silvestri. 

Lagena  laevis  (Montagu)  Silvestri,  1900,  p.  244,  pi.  6,  figs.  74,  75. 

Examples  are  rare,  but  they  occur  at  a  fair  number  of  stations.. 
—Locality  :  Chiefly  at  Nos.  1,  6,  11,  15,  17,  22,  42-44.      . 

Lagena  gracillima  Seguenza  sp. 

Amphorina  gracilis  Costa,  1856,  p.  121,  p.  11,  fig.   11. 
Am ph or ina  gracillima  Seguenza,  1862,  p.  51,  pi.  1,  fig.  37. 

Eight  specimens  occur  which  are  all  curved. — Locality  :  No.  44. 
Besides  these  specimens,  only  two  or  three  others  were  found. — 
Locality  :  Uncertain. 

Lagena  elongata  Ehrenberg  sp. 
Miliola  elongata  Ehrenberg,  1854,  pi.  25,  1a,  fig.  1. 

I  do  not  think  these  can  be  separated  from  L.  gracillima 
Seguenza  sp.,  as  they  appear  to  pass  insensibly  from  one  form  to 
the  other.  Seven  specimens  occur,  also  two  or  three  doubtful 
examples. — Locality  :  Six  at  No.  43,  and  one  at  No.  2. 

Lagena  aspera  Keuss  (PI.  15,  figs.  11-13). 
Lagena  aspera  Eeuss,  1861,  p.  305,  pi.  1,  fig.  5. 

Pi.  15,  fig.  11.  This  is  in  good  condition,  except  that  the  neck 
is  broken.  The  protuberances,  which  are  arranged  in  lines,  are, 
I  think,  tubular. — Locality  :  No.  17. 

On  another  square  are  two  smaller  specimens,  with  very  small 
protuberances  ;  these  also  have  the  neck  fractured.  They  appear 
to  be  a  weak  form  of  the  above. — Locality  :  Uncertain. 

PI.  15,  £g.  12.  Two  specimens  only  occur  ;  the  one  figured  is  in 
a  very  opaque  condition,  the  other  is  clear  but  much  smaller. — 
Locality  :  Nos.  1,  22. 

PI.  15,  fig.  13.  Three  specimens  found,  the  neck  being  bent  to 
one  side  in  each  case.  It  is  not  unlikely  that  future  investigation 
will  reveal  a  connection  between  these  forms  and  L.  striatopunctata. 
—Locality  :  No.  43. 

There  are  also  two  oval  tests,  which  have  the  protuberances, 
and  the  lines  in  which  they  are  arranged,  farther  apart.  The 
protuberances  are  very  minute. — Locality  :  No.  10. 


168    HENRY   S1DEB0TT0M    ON    LAGENAE   OF   THE   SOUTH-WEST    PACIFIC. 

Lagena  rudis  Reuss  (PI.  15,  fig.  14). 

Lagena  rudis  Reuss,  1862  (1863),  vol.  46,  p.  336,  pi.  6,  fig.  82. 

A  single  example.  The  test  is  opaque  and  of  a  faint  silvery- 
yellow  colour. — Locality  :  No.  24. 

Lagena  ampulla-distoma  Rymer  Jones. 

Lagena  vulgaris  var.   ampulla-distoma  Rymer  Jones,  1872,  p.  63, 
pi.  19,  fig.  52.     See  also  +  p.  384. 

Locality  :  Nos.  1,  2,  3,  8,  19,  22,  24,  42,  43. 

Mr.  Millett,  1901,  p.  6,  mentions  two  other  localities  for  this 
species,  besides  the  Malay  Archipelago  ;  it  may  therefore  be  worth 
while  to  state  that  I  have  since  recorded  it  from  the  coast  of 
Delos  and  Palermo. 

Lagena  hispida  Reuss  (PI.   15,  fig.  15). 

Sphaerulae  hispidae  Soldani,  1798,  p.  53,  pi.  17,  v,  x. 

Lagena  hispida  Reuss,  1858,  p.  434. 

Lagena  hispida  Reuss,  1862  (1863),  p.  335,  pi.  6,  figs.  77-79. 

In  one  form  or  another  this  is  found  at  nearly  all  the  stations. 
There  is  great  variation  in  size,  and  shape  of  the  tests,  and  many 
of  the  small  ones  have  a  long  entosolenian  tube  at  the  opposite 
end  from  the  neck,  so  that  it  is  difficult  in  some  cases  to  say  which 
is  the  right  end  up.  If  turned  one  way,  they  might  be  treated  as 
apiculate  forms. 

PI.  15,  fig.  15.  The  orifice  is  circular  and  sunk  in  a  depression. 
The  oral  end  of  the  test  is  surrounded  by  a  series  of  short  spines. 
A  solitary  example.     Locality  :  No.  24. 

*  PI.  15,  fig.  1.  Ten  specimens  occur. — Locality  :  Nos.  5,  6,  8, 
and  a  single  example  at  either  Nos.  41  or  42. 

Lagena  hispida  Reuss,  compressed  form. 

+  P1.  15,  fig.  2.— Locality:  Nos.  1-3,  5-7,  10,  24,  33,  34,  36, 
38  40,  42. 

Lagena  hispida  Reuss  var.  tubulata  Sidebottom  (PI.  15,  fig.  16). 

Lagena    hispida  Reuss   var.   tubulata    Sidebottom,    1912,    Joum. 
Q.  M.  C,  p.  385,  pi.  15,  figs.  3-5. 

PI.  15,  fig.  16.  Nearly  all  the  smaller  tests  have  their  necks 
broken,    and  a  few  are  very  large,  as  can  be  judged   from   the 


HENRY   SIDEBOTTOM    OX   LAGENAE    OF    THE   SOUTH-WEST    PACIFIC.     169 

drawing.  The  largest  specimens  have  the  body  much  clogged  by 
exogenous  shell-growth,  or  debris,  through  which  small  spines 
often  project. — Locality  :  Nos.  17,  19.  24.  25,  35.  36.  Always  rare. 
+  P1.  15,  fig.  5.  This  variation,  which  is  much  more  delicate  in 
every  way.  is  found  at  many  stations. — Locality:  Xos.  1-11.  24, 
25.  33,  35,  36.  39. 

Lagena  striata  d'Orbigny  sp.  (PL   15.  fig.   17). 
Oolina  striata  d'Orbigny,  1839,  p.  21,  pi.  5,  fig.  12. 

Many  examples  at  numerous  stations.  They  vary  remarkably 
both  in  size  and  decoration.  Many  are  apiculate.  -f-  See  remark-. 
p.  386. 

PI.  15.  fig.  17.  In  this,  the  fine  costae  project  at  the  base.  The 
neck  is  bent  to  one  side,  the  body  of  the  test  is  also  slightly 
■curved.  On  a  square  by  themselves  are  fifteen  tests  which  have 
the  contour  of  L.  clavata,  with  the  point  at  which  the  test  begins 
to  narrow  towards  the  base  sharply  angular.  Only  two  are 
marked  on  the  chart.  Locality  :  Nos.  1,  3-5.  7.  8.  12.  17.  21,  24, 
34.  39.  40. 

Lagena  (Amphorina)  Lyellii  Seguenza  sp.  is  found  frequently. 
This  form  may  be  treated  either  as  L.  striata,  or  L.  sulcata  in  an 
apiculate  condition. 

*  PI.  15.  fig.  6.  Twenty-three  specimens  are  on  the  slide. — 
Locality  :  Nos.  2.  3.  4. 

*  PI.  15,  fig.  8.  Fourteen  fine  examples  occur,  and  a  number 
of  smaller  ones.  Taking  the  whole  series  into  account  they  pass 
gradually  into  L.  Lyellii  Seguenza. — Locality;  Nos:  2-12.  15,  17. 
21,  24,  29,  31,  33,  34.  39.  40,  42,  43. 

+  EL  15,  fig.  9.  Five  typical  tests  are  on  the  slide,  but  they 
are  mixed  with  others  that  are  not  typical,  and  so  the  exact 
locality  cannot  be  given  with  certainty.  They  were  found,  how- 
ever, at  one  or  two  of  the  following  stations. — Locality  :  ZSTos. 
1,  5,  11,  13. 

On  another  slide  two  examples  are  placed. — Locality :  2Sos. 
23.  24. 

Lagena  striata  d'Orbigny  sp.  var.  tortilis  Egger. 

Lagena  tortilis  Egger,  1893,  p.  329,  pi.  10,  figs.  61-63. 

Two  examples  only. — Locality  :  Nos.  43.  44. 

Journ.  Q.  M.  C.,  Series  II.— No.  73.  12 


170    HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC 

Lagena  striata  d'Orbigny  sp.   var.  striatotubulata   Sidebottom. 

Lagena    striata    d'Orbigny    sp.    var.    striatotubulata    Sidebottom,. 
1912,  Journ.  Q.  M.  C.,  p.  387,  pi.  15,  figs.  11,  12. 

This  is  well  represented.  A  good  many  are  more  or  less- 
fractured,  otherwise  they  are  clean  and  fresh-looking. — Locality  r 
Nos.  4-12,  23,  24,  29,  33,  34,  39,  40. 

Lagena  distoma  Parker  and  Jones. 

Lagena  laevis  var.  striata  Parker  and  Jones,  1857,  p.  27S,  pi.  11, 
fig.  24. 

There  is  a  single  large  specimen  and  it  agrees  with  the 
Challenger  figure,  pi.  58,  fig.  11. — Locality  :  No.  2. 

There  are  about  twelve  examples  which  have  their  sides  slightly" 
curved  and  parallel  as  in  the  type. — Locality :  Uncertain. 

Lagena  lineata  Williamson  sp. 

Entosolenia  lineata  Williamson,  1848,  p.  18,  pi.  2,  fig.  18. 

Many  examples  found. — Locality :  Nos.  1,  2,  4,  5,  9,  10,  13-15, 
17-20,  22,  24,  25,  36,  38,  42-44. 

+  PI.  15,  fig.  15.  The  variety  with  the  costae  curved  occurs  at 
many  stations. 

Non-apiculate  forms  also  are  present. 

Lagena  variata  Brady. 

Lagena   variata  Brady,    1881,  Quart.   Journ.  Micr.    Sci.,  vol.   21,. 

N.S.,  p.  61. 
Lagena  variata  Brady,  1884,  p.  461,  pi.  61,  fig.  1. 

Only  two  typical  examples. — Locality  :  Uncertain. 

+  PL  15,  fig.  13.  The  neck  of  the  test  is  in  many  cases  not  so 
long  as  in  the  figure  referred  to. — Locality :  Nos.  14,  15,  17,  19, 
22,  24,  25,  44. 

Lagena  costata  Williamson  sp.  (PI.  15,  figs.  18,  19). 

Entosolenia  costata  Williamson,  1858,  p.  9,  pi.  1,  fig.  18. 

Occurs  frequently,  typical  and  otherwise,  sometimes  apiculate. 
PL  15,  fig.  18.     This  appears  to  be  an  elongate  form  with  from. 


HENRY   SIDEBOTTOiM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     171 

eight  to  ten  costae.  Entosolenian  tube  straight. — Locality : 
Ud certain  ;  probably  No.  22  and  a  few  other  stations. 

PI.  15,  fig.  19.  These  appear  to  be  the  same,  but  they  have 
only  six  costae,  and  occur  more  frequently. — .Nos.  15,  17-20,  23, 
24,  29,  33-36. 

+  P1.  15,  fig.  16. — Locality:  Many  stations  throughout  the 
whole  series. 

+  P1.  15,  fig.  19.— Locality:  No.  43. 

Lagena  acuticosta  Reuss  (PI.  15,  fig.  20). 
Lagena  acuticosta  Reuss,  1861,  p.  305,  pi.  1,  fig.  4. 

An  unsatisfactory  species,  for  it  is  linked  closely  with  L.  costata 
on  the  one  hand,  and  L.  sulcata  on  the  other. — Locality:  Many 
stations  up  to  No.  22  ;  afterwards  extremely  rare. 

PI.  15,  fig.  20.  An  odd  specimen,  probably  a  very  weak  form. 
— Locality :  Uncertain. 

+  PI.  15,  fig.  22.  Tests  similar  or  nearly  so  oc^ur,  but  they  are 
not  so  large. — Locality  :  Nos.  2,  7,  and  a  few  other  stations. 

Lagena  melo  d'Orbigny  sp. 
Oolina  melo  d'Orbigny,  1839,  p.  20,  pi.  5,  fig.  9. 

There  are  several  fine  typical  examples  and  a  few  small  ores 
on  the  slide,  but  as  they  are  mixed  with  other  varieties  the 
locality  cannot  be  determined. 

The  form  with  the  cross-bars  sunk,  which  is  assigned  by 
Reuss  to  L.  catenulata  Williamson,  1862  (1833),  pi.  6,  fig.  75,  is 
also  present. 

Lagena  hexagona  Williamson  sp.  (PI.  15,  figs.  21-23). 

Entosolenia  squamosa  var.  hexagona  Williamson,  1848,  p.  20,  pi.  2, 
fig.  23. 

Very  many  beautiful  specimens  occur ;  some  are  globular, 
others  pyriform,  with  and  without  necks.  The  depth  and  size  of 
the  mesh  var}7  greatly. 

A  few,  w^hich  I  take  to  be  L.  geomeirica  Reuss,  1862  (1863), 
pi.  5,  fig.  74,  are  exquisite,  although  the  arrangement  of  their 
cells  is  not  always  parallel.  The  cells  are  deep,  and  their  sides 
exceedingly  delicate.  Several  have  short  necks.  I  have  not 
attempted    to  draw    them,    as    I    could    not    have  produced  the 


172    HENRY    SIDEBOTTOM    ON    LAGENAE    OF   THE    SOUTH-WEST   PACIFIC. 

desired    effect. — Locality:  Again    the    mixing    of    the    varieties 
prevents  me  from  giving  any  definite  information. 

There  are  a  few  which  appear  to  be  the  same  as  the  one 
figured  by  Brady  in  the  Challenger  Report,  pi.  58,  fig.  33,  of 
which  the  angles  of  the  cells  tend  to  become  spinous,  especially 
at  the  base  of  the  test.  This  peculiarity  seems  to  be  feebly  indi- 
cated in  Brady's  figure. 

PI.  15,  fig.  21.  Several  of  this  elegant  form  occur. — Locality  : 
Uncertain. 

PI.  15,  fig.  22.     A  globular  variety. 

PI.  15,  fig.  23.  A  compressed  variation  of  the  above,  but  of 
smaller  size.  These  two  forms  are  placed  together  on  the  slide. 
— Locality ;  Taking  the  two  forms  together  they  are  marked 
Nob.  2-5,  13,  17-20,  44. 

Lagena  squamosa  Montagu  sp. 

Vermiculum  sqtiamosum  Montagu,  1803,  Test.  Brit.  p.  526,  pi.  14, 
%.  2. 

A  few  only  are  present. — Locality  :  Uncertain. 

Lagena  exsculpta  Brady. 

Lagenulina    sulcata    Terquem,     1876,    Anim.    sur    la    Plage    de 

Dunkerque,  fasc.  2,  p.  68,  pi.  7,  fig.   9. 
Lagena  exsculpta  Brady,  Quart.   Journ.  Micr.  Sri.,  vol.  xxi.,  N.S., 

p.  61. 
Lagena  exsculpta  Brady,  1884,  p.  467,  pi.  58,  fig.  1  ;  pi.  61,  fig.  5. 

Five  examples  found,  and  they  are  compressed.  Three  of  them 
are  in  poor  condition.  These  latter  are  not  quite  typical,  as 
the  sculptui  e  becomes  irregular  at  the  base. — Locality  :  ISTos. 
37,  39. 

Lagena  sulcata  Walker  and  Jacob  sp.  (PI.  15,  figs.  24,  25). 

Serpula  (Lagena)  striata  sulcata  rotunda  Walker  and  Boys,   1784, 

p.  2,  pi.  1,  fig.  6. 
Serpula  (Lagena)  sulcata  Walker  and  Jacob,  1798,  p.  634,  pi.  14, 

fig.  5. 

This  common  foraminifer  is  well  represented.  In  some  the 
body  of  the  test  is  globular,  and  in  others  cylindrical.     Apicu- 


HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     173 

late  forms  also  occur.— Locality  :  Nos.  4,  14,  15,  20,  24,  26,  38, 
42-44,  and  a  few  others. 

PI.  15,  fig.  24.  This  is  closely  allied  to  L.  alifera  Beuss,  1870, 
p  467.— Von  Schlicht,  1870,  pi.  3,  figs.  15,  16,  21,  22.— Locality  : 
Nos.  3.  10,  and  two  or  three  others. 

PI.  15,  fig.  25.  This  form,  known  as  L.  sulcata  var.  interrupta 
Williamson,  is  hardly  worthy  of  a  varietal  name,  as  it  is  not  at 
all  uncommon  for  some  of  the  costae  or  striae,  both  in  L.  sulcata 
and  L.  striata,  to  be  shorter  than  the  others. 

Lagena  plumigera  Brady  (PI.  15,  fig.  26). 

Lagena  plumigera  Brady,    1881,  Quart.  Journ.  Jficr.  Sci.,  vol.  21, 

N.S.,  p.  62. 
Lagena  plumigera  Brady,  1884,  p.  465,  pi.  58,  figs.  25,  27. 

Two  of  the  tests  are  similar  to  the  one  figured  ;  several  others 
are  smaller  and  much  damaged. — Locality :  Nos.  1,  2,  43. 

Lagena  semilineata  Wright  (PI.  15,  fig.  27). 

Lagena  semilineata  Wright,  1884-5,  App.  9,  1886,  p.  320,  pl.  26, 
fig.   7. 

Evidently  a  bold  form  of  L.  semilineata. — Locality:  Three 
examples  at  Station  No.  2. 

Lagena  gracilis  Williamson. 

Lagena  gracilis  Williamson,  1848,  p.  13,  pl.  1,  fig.  5.. 

This  protean  species  is  found  at  many  stations  throughout 
the  whole  series.  All  the  forms  represented  in  the  Challenger 
Report,  1884,  appear  to  be  present.  No  line  of  demarcation  can 
be  drawn  between  this  species  and  apiculate  forms  of  L.  sulcata 
and  Z.  striata ;  they  are  also  linked  with  L.  distoma  Parker  and 
Jones. 

Lagena  quinquelatera  Brady. 

Lagena  quinquelatera  Brady,   1881,  Quart.  Journ.  Micr.  Sci.,  vol. 

21,  N.S.,  p.  60. 
Lagena  quinquelatera  Brady,  1884,  p.  484,  pl.  61,  figs.  15,  16. 

I  take  this  to  be  a  variety  of  L.  gracilis. 
Two  specimens  only. — Locality  :  No.  2. 


174    HENRY   SIDEBOTTOM    ON   LAGENAE   OF  THE   SOUTH-WEST   PACIFIC. 

Lagena  semistriata  Williamson. 

Lagena  striata  var.  /?  semistriata  Williamson,   1848,  p.  14,  pi.  1, 
figs.  9,  10. 

The  great  majority  are  small.  Some  have  the  neck  bent  to 
one  side  and  the  body  slightly  curved.  A  few  are  cylindrical  and 
others  have  the  contour  of  L.  clavata  d'Orbigny. — Locality  :  Nos. 
1,  20-22,  29,  42-44. 

Lagena  crenata  Parker  and  Jones  var.  (PI.  15,  fig.  28). 

Lagena  crenata  Parker  and  Jones,  1865,  p.  420,  pi.  18,  fig.  4. 

They  are  not  typical,  but  I  think  they  are  best  placed  under 
the  above  heading.  The  projecting  parts  at  the  base  run  partly 
towards  its  centre  as  blades.  The  neck  is  not  decorated.  A  few 
of  the  examples  are  not  so  slim  as  the  one  figured,  and  have  their 
sides  slightly  convex.  Thirteen  specimens  occur.  I  cannot  give 
all  the  stations  at  which  they  are  found,  but  the  following  may 
be  indicated.     Locality  :  22,  43. 

Lagena  Thornhilli  Sidebottom  (PI.  15,  fig.  29). 

Lagena   Thornhilli    Sidebottom,    1912,    Journ.   Q.M.C.,    p.    390, 
pi.  15,  fig.  26. 

They  differ  slightly  from  the  one  figured  at  the  above  reference, 
for  the  upper  parts  of  the  wings  are  joined  together  so  as  to 
form  a  hood,  as  shown  in  the  figure.  In  one  of  the  examples 
the  three  cavities  formed  by  the  hood  are  blocked  with  exogenous 
shell-growth. 

Four  examples  occur. — Locality  :  6,  8,  29. 

Lagena  stelligera  Brady. 

Lagena  stelligera  Brady,  1881,  Quart.  Journ.   J/icr.   Sci.,  vol.  21, 

N.S.,  p.  60. 
Lagena  stelligera  Brady,  1884,  p.  466,  pi.  57,  figs.  35,  36. 

A  good  many  agree  with  Brady's  Challenger  figure,  pi.  57, 
fig.  35,  but  some  are  more  slender,  and  several  are  very 
minute. 

See  remarks,  +  pp.  391,  392.— Locality :  Nos.  5,  14,  17-19,  21, 


HENRY   SIDEBOTTOM    ON   LAGENAE   OF  THE   SOUTH-WEST   PACIFIC.     175 

22,  also  Nos.  23,  24,  29,  32,  33,  35,  37,  39-41.     From  these  latter 
stations  a  few  of  the  "  nude  "  form  were  obtained. 

*  PL  16,  fig.  1.     In  most  of   the  specimens,  some  of  the  costae 
-are  more  prominent  than  the  others,  but  none  of  them  are  "inter- 
rupted," as  in  the  figure  referred  to. — Locality :  10,  22-24,  36,  39. 

+  P1.  16,  fig.  2.  Numerous  examples  of  this  "  nude  "  variety 
are  on  the  slides,  some  having  very  long,  delicate  necks.  The 
apiculate  portion  varies  both  in  width  and  length.  Two  very 
large  tests  were  found,  and  except  for  the  absence  of  the  costae 
they  agree  well  with  the  Challenger  figure,  pi.  57,  fig.  36. — 
Locality :  Nos.  2,  3,  5,  12,  19,  23,  24,  29,  32,  33,  35,  36,  38-40. 

+  P1.  16,  fig.  3.— Locality:  Nos.  3-7,  9,  10,  13,  17,  23,  24,  26, 
29,  33  35,  39,  40. 

*  PI.  16,  fig.  4.  Compressed.  Nine  examples  found. — Locality: 
Nos.  2,  24.     Other  stations  uncertain. 

Lagena   stelligera    Brady   var.  eccentrica   Sidebottom  (PI.   15, 

fig.  30). 

Lagena  stelligera  Brady  var.  eccentrica   Sidebottom  1912,  Journ. 
Q.  M.  O.,  p.  392,  pi.  16,  figs.  5,  6. 

PI.  15,  fig.  30.  On  this  specimen  the  ridge  at  the  base  is 
scarcely  perceptible.  Two  or  three  only  found. — Locality:  Un- 
certain. 

+  PI.  16,  fig.  5.     Not  typically  represented  in  these  gatherings. 

+  P1.  16,  fig.  6.  The  examples  generally  have  the  ridge  at  the 
base  carried  farther  up  the  side  of  the  test. — Locality  :  Nos.  11, 
14,  37. 

Lagena    stelligera     Brady    var.    eccentrica    Sidebottom,     com- 
pressed form  (PL   15,   fig.   31). 

This  is  the  compressed  form,  and  some  of  the  specimens  from 
No.  43  are  in  fine  condition. — Locality  :  Nos.  10,  13.  14,  19,  20- 
43.     Very  rare,  except  at  No.  43. 

Lagena  striatopunctata  Parker  and  Jones. 

Lagena    sulcata    var.   striatoptmctata    Parker    and    Jones,    1865, 
p.  350,  pi.  13,  figs.  25-27. 

Various  forms  are  present.     Some  have  the  neck  bent  to  one 
.side,  others  have  only  a  very  short   neck.     The  body  of  the  test 


176    HENRY    SIDEBOTTOM    ON  LAGENAE   OF  THE   SOUTH-WEST   PACIFIC. 

also  varies  greatly,  being  occasionally  almost  globular. — Locality  : 
Nos.  1-3,  22,  24  26,  33,  34,  38,  42,  43. 

Lagena  striatopunctata  Parker  and  Jones  (?)   var.  complexa 

Sidebottom. 

Lagena  striatopunctata  Parker  and  Jones  (?)  var.  complexa  Side- 
bottom,  1912,  Journ.  Q.  M.  C,  p.  393,  pi.  16,  fig.  11. 

"*"  PL  16,  fig.  11.  None  of  the  tests  are  in  perfect  condition, 
all  showing  signs  of  the  disintegration  mentioned  at  the  above 
reference. — Locality  :  Nos.  7,  9,  24. 

Lagena    striatopunctata   Parker   and    Jones   var.   inaequalis 

Sidebottom. 

Lagena  striatopunctata  Parker  and   Jones  var.   inaequalis    Side- 
bottom,  1912,  Journ.  Q.  J/.  C,  p.  393,  pi.  16,  fig.  12. 

Three  tests  are  on  the  slide,  but  only  two  belong  to  this  variety. 
— Locality  :  Two  of  the  following,  Nos.  4,  10,  11. 

Lagena  striatopunctata  Parker  and  Jones  var.  spiralis  Brady. 

Lagena  spiralis  Brady,  1884,  p.  468,  pi.  114,  fig.  9. 

Locality :  Nos.  1-4,  22,  37,  38,  43,  44.  Very  rare  except  at 
No.  1. 

Lagena  Fieldeniana  Brady. 

Lagena  Fieldeniana  Brady,  1878,  Ann.  Mag.  Nat.  Hist.  (5)  vol.  1. 

p.  434,  pi.  20,  fig.  4. 
Lagena  Fieldeniana  Brady,  1884,  p.  469,  pi.  58,  figs.  38,  39. 

A  solitary,  rather  rotund  example,  of  which  the  neck  is  broken 
off  short. — Locality  :  Uncertain. 

Lagena  desmophora  Rymer  Jones. 

Lagena   vulgaris   var.    desmophora    Bymer    Jones,   1872,    p.    54, 
pi.  19,  figs.  23,  24. 

The  specimens  are  typical  and  in  good  condition.  All  are,  or 
have  been,  apiculate.  The  number  of  spines  at  the  bate  varies 
from  one  to  four. — Locality :  Nos.  2,  5,  7-11,  13,  33,  40. 


HENRY    SIDEBOTTOM   ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     177 

Lagena  foveolata  Reuss. 

Lagena  foveolata  Reuss,  1862  (1863),  p.  332,  pi.  5,  fig.  65. 
Lagena  No.  25,  von  Schlicht,  1870,  p.  10,  pi.  3,  fig.  25. 

Three  or  four  only  occur.  The  sculpture  of  the  test  is  ex- 
ceedingly fine. — Locality  :  No.  43,  and  one  or  two  other  stations 
which  are  uncertain. 

Lagena  foveolata  Eeuss  var. 

Lagena  foveolata  Reuss  var.   Sidebottom,  1912,  Journ.  Q.  M.  0.r 
p.  395,  pi.  16,  figs.  16,  17. 

It  is  possible  that  further  investigation  may  reveal  this  to  be 
an  apiculate  form  of  one  of  the  variations  of  L.  melo  d'Orbigny 
sp.— Locality .-  Nos.  1,  2,  4,  6,  8,  10,  12,  14,  15,  17,  19,  21,  22, 
24,  33,  36,  38,  40,  42-44. 

Lagena  foveolata  Reuss  var.  spinipes  Sidebottom. 

Lagena  foveolata  R,3uss  var.  spinipes  Sidebottom,    1912,  Journ. 
Q.  M.  67.,  p.  396,  pi.  16,  figs.  18-20. 

The  tests  are  not  in  the  best  condition,  and  in  some  instances 
the  spines  appear  to  be  absent,  or  scarcely  perceptible.  The 
rotund  form  does  not  occur. — Locality :  Fifteen  specimens  at 
at  No.  2,  three  at  No.  3,  four  at  No.  4. 

Lagena  foveolata  Reuss  (?)  var  paradoxa  Sidebottom  (PI.  15, 

fig.  32). 

Lagena   foveolata    Reuss   (?)    var.    paradoxa    Sidebottom,    1912, 
Journ.  Q.  M.  C,  p.  395,  pi.  16,  figs.  22,  23. 

This  is  one  of  the  commonest  foraminifera  in  these  gatherings. 
The  tests  vary  greatly  in  size  and  shape. — Locality  :  Nos.  1-22, 
(except  No.  17),  23-26,  29,  31,  33,  34-36,  39-41,  44. 

Lagena  lamellata  Sidebottom. 

r 

Lagena   lamellata    Sidebottom,    1912,  Journ.   Q.   M.    C,   p.   396, 
pi.  16,  figs.  24,  25. 

I  can  only  identify  four  tests. — Locality :  Two  occur  at  No.  43  i 
the  other  station  or  stations  are  uncertain. 


178     HENRY   SIDEBOTTOM   ON    LAGENAE    OF   THE   SOUTH-WEST    PACIFIC. 

Lagena  Hertwigiana  Brady  (PI.  15,  fig.  33). 

Lagena  Hertwigiana  Brady,  1881,  Quart.  Journ.  Micr.  Sci.,  vol.  21, 

N.S.,  p.  62. 
Lagena  Hertwigiana  Brady,  1884,  p.  470,  pi.  58,  fig.  36. 

The  figure  in  my  copy  of  the  Challenger  Report,  pi.  58, 
fig.  36,  does  not  show  the  reticulation  referred  to  in  the  description 
of  the  species  in  the  text,  p.  470.  In  the  three  or  four  specimens 
found  in  these  soundings,  the  surface  is  roughened  and  the 
perforations  show  very  plainly. — Locality  :  Uncertain,  with  the 
exception  of  No.  43. 

Lagena  Hertwigiana  Brady  var.  undulata  Sidebottom. 

Lagena    Hertwigiana    Brady    var.    undulata    Sidebottom,    1912, 
Journ.  Q.  M.  C,  p.  397,  pi.  16,  figs.  26-28. 

Many  examples  occur.  — Locality  :  Nearly  all  the  stations,  but 
chiefly  Nos.  2,  7,  10,  17,  24,  34,  43. 

Lagena  pacifica  Sidebottom. 

Xagena  pacijica  Sidebottom,  1912,  Journ.  Q.  M.  C,  p.  398,  pi.  16 f 
fig.  29. 

Only  two  or  three  specimens  found. — Locality  :  Uncertain. 

Lagena  splendida  sp.  nov.  (PI.   16,  fig?.  1-3). 

I  am  quite  at  a  loss  how  to  describe  this  exquisite  Lagena. 
-adequately,  and  I  am  unable  to  draw  it  owing  to  the  complexity 
of  its  decoration,  which  is  exceedingly  minute.  The  test  glistens 
and  most  probably  it  has  been  apiculate.  The  neck  is  fractured. 
There  is  a  second  specimen  which  I  think  is  the  same,  but  there 
is  a  slight  difference  in  its  appearance  which  I  am  unable  to 
explain.     It  is  apiculate. — Locality  :   Uncertain. 

Note. — Not  being  able  to  get  a  satisfactory  definition  with  my 
microscope,  I  submitted  the  test  to  Mr.  Earland  for  examination, 
who  had  better  means  of  lighting  up  the  test  than  I  had.  His 
observations  were  made  with  the  assistance  of  a  Zeiss  vertical 
illuminator  and  daylight  instead  of  artificial  light.  He  writes  as 
follows  : 


HENRY   SIDEBOTTOM    ON    LAGENAE    OF   THE   SOUTH-WEST    PACIFIC.     179 

"  The  markings  appear  to  be  knife-edged  costae,  from  one  side 
•of  which  triangular  processes  project  at  intervals.  The  apex  of 
the  process  barely  touches  the  inner  side  of  the  adjoining  co^ta. 
.  .  .  The  triangular  processes  are  Hush  with  the  costae  at  their 
base,  but  apparently  sink  away  towards  the  apex,  which  is 
probably  but  little  raised  above  the  wall  of  the  test.  The  sunken 
parts  between  the  processes  have  a  matt  surface,  whereas  the 
processes  and  costae  are  quite  translucent." 

I  may  say  that  my  own  examination  of  the  test  agrees  to  a 
great  extent  with  the  above,  but  I  think  the  edges  of  the  costae 
are  waved  (see  PI.  16,  fig.  3). 

In  a  second  communication  Mr.  Earland  writes  :  "  I  succeeded 
in  getting  a  stereoscopic  view  of  the  shell  under  a  ^  in.  yesterday, 
and  it  gave  rather  a  fresh  view  of  its  structure.  It  seemed  to  be 
covered  with  lines  of  pyramidal  points  in  broken  lines.  Each 
pyramid  is  a  blunt  spine." 

I  have  not  succeeded,  however,  in  seeing  these  characters  of  the 
test. 

The  figure  (PI.  16,  fig.  2)  gives  the  effect  of  what  I  think  I  see 
under  the  microscope,  and  it  coincides  to  a  great  extent  with 
Mr.  Earland's  first  description,  though  the  details  given  in  his 
second  communication  do  not  appear  to  me  to  be  necessarily 
contradictory.  I  wish  to  acknowledge  my  sense  of  the  trouble 
Mr.  Earland  has  taken  in  the  matter. 

Lagena  spumosa  Millett  (PI.  16,  fig.  4). 

Lagena  spumosa  Millett,  1901,  p.  9,  pi.  1,  fig.  9. 

Most  of  the  tests  are  slightly  curved  at  the  oral  end,  but  the 
■"  bird's-clawlike "  process  is  more  slender  than  is  indicated  in 
Mr.  Millett's  illustration.  Several  are  more  elongate  than  the 
one  figured.—  Locality  .•  Frequent  at  No.  22 ;  Nos.  24.  38,  40,  42, 
43,  and  a  few  other  stations. 

Lagena  spumosa  Millett,  var. 

Lagena  spumosa  Millett  var.   Sidebottom,  1912,  Journ.  Q.  21.  C, 
p.  398,  pi.  16,  fig.  30. 

It  is  curious  that  the  aboral  end  of  the  test  appears  to  have 
teen  slightly  abraded,  I  think  in  all  cases. — Locality  :  Nos.  4,  6, 
7,  10,  11^  13,  24,  25,  33,  35,  39,  40,  42,  43. 


180    HENRY    SIDEBOTTOM    ON   LAGENAE   OF  THE   SOUTH-WEST   PACIFIC. 

Lagena  Chasteri  Millett. 
Lagena  Chasteri  Millett,  1901,  p.  11,  pi.  1,  fig.  11. 
See  my  remarks  on  the  type-form  +  p.  398. 

Lagena  Chasteri  Millett  (var.  ?). 

Lagena     Chasteri     Millett    (var.    ?)     Sidebottom.     1912,     Journ.. 
Q.M.C.,  p.  398,  pi.   1G,  figs.  32-34. 

Many  occur,  but  I  am  quite  unable  to  separate  this  variation 
from  the  type,  for  the  curious  little  "  stopper "  at  the  orifice  is 
never  so  pronounced  as  in  Mr.  Millett's  figure,  and  is  often 
apparently  absent.  Taking  the  type-form  and  the  variation  to- 
gether, for  they  are  mixed  on  the  slides,  they  occur  as  follows  : — 
Locality ;  Nos.  1-4,  22,  34,  38,  and  frequently  at  Nos.  42-44. 

Lagena  pannosa  Millett  var. 

Lagena  pannosa  Mille;t  var.  1901,  p.  11,  pi.  1,  fig.  14. 

It  is  probable  that  two  or  three  examples  of  this  variation  are^ 
present. — Locality  :  Uncertain. 

Lagena  intermedia  Sidebottom. 

Lagena   intermedia   Sidebottom,    1912,    Journ.   Q.M.C.,    p.    399,. 
pi.  17,  figs.  1-3. 

Locality :  Nos.  3,  11,  12,  23,  24,  29,  32,  39-41. 

Lagena  quadralata  Brady. 

Lagena  quadralata  Brady,  1881,  Qua/rt.  Journ.  Micr.  Sci.,  vol.  xxL 

(N.S.),  p.  62. 
Lagena  quadralata  Brady,  1884,  p.  464,  pi.  61,  fig.  3. 

In  the  Challenger  Report  Brady  states  that  this  Lagena  is. 
allied  to  the  Lagena  alifera  of  Reuss.  I  should  prefer  to  con- 
sider it  as  a  variety  of  L.  lagenoides  Williamson  var.  tenuistriata 
Bradv,  for  we  know  that  this  latter  occurs  in  the  trifacial 
condition  (see  *  PI.  19,  fig.  5),  and  therefore  it  is  not  surprising 
to  find  it  with  four  equidistant  keels ;  also  I  have  a  good  example 
of  Jj.  lagenoides  with  five  equidistant  keels.  The  specimen  found 
is  very  small  and  not  in  the  best  condition.  I  think  the  wings 
are   tubular,   but   cannot   be  certain.     On   the  same   slide   there- 


HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     181 

are  two  examples  with  three   keels,  and  two  with  five  keels. — 
Locality  :  One  specimen  at  No.  1.     Other  stations  uncertain. 

Note. — One  or  two  examples  occur  with  four  keels  which  are 
not  tubulated.     These  I  should  place  as  a  variety  of  L.  striata. 

Lagena  sp.  in  cert. 

Lagena  sp.  incert.  Sidebottom,  1912,  Journ.  Q.  M.  C,  p.  399,  pi.  17, 
figs.  4,  5. 

Locality :  Three  examples  at  No.  2,  two  at  No.  24. 

Lagena  laevigata  Reuss,  sp.  (PL  16,  fig.  5). 
Fissurina  laevigata  Reuss,  1850,  p.  366,  pi.  46,  fig.  1. 

Large  and  small  examples  of  the  type-form  occur,  but  they  are 
not  numerous.  It  is  impossible  to  separate  L.  laevigata  from 
L.  acuta,  as  the  one  passes  insensibly  into  the  other.  Many  other 
examples  are  present  in  which  the  orifice  is  not  central.  Forms 
ranging  round  Fissurina  oblonga  Reuss,  1862  (1863),  pi.  7,  fig.  89, 
are  frequent,  and  are  found  at  many  stations.  A  few  specimens 
occur  that  are  circular  in  outline. 

PI.  16,  fig.  5.  There  are  two  sets  of  these  and  they  vary  a  little. 
Some  have  the  appearance  of  being  subcarinate,  but  this  seems 
to  be  caused  by  the  test  being  clearer  at  its  edge  than  at  any  other 
part.  Only  two  or  three  examples  have  the  spines  at  the  orifice 
well  developed,  and  most  have  a  small  wing  at  either  side  of  the 
neck.     There  is  no  internal  tube. — Locality  :  Nos.  42-44. 

Note. — These  are  not  far  removed  from  L.  falcata  Chaster, 
1892,  p.  6,  pi.  1,  fig.  7.  On  another  square  (locality  uncertain) 
there  is  one  typical  form,  and  there  are  also  one  or  two  others 
that  are  carinate  at  the  base,  which  seem  to  be  intermediate 
between  L.  falcata  and  Mr.  Millett's  figure  of  L.  marginata  var. 
Millett,  1901,  p.  497,  pi.  8,  fig.  21. 

Lagena  laevigata  Reuss  sp.  var.  virgulata  Sidebottom  (PI.  16, 

fig.  6). 

Lagena    laevigata    Reuss   sp.    var.    virgulata     Sidebottom,    1912, 
Journ.  Q.  21.  C,  p.  400,  pi.  17,  fig.  8. 

PI.  16,  fig.  6.  A  few  fine  examples  placed  amongst  others  which 
are  too  opaque  for  me  to  be  certain  whether  they  belong  to  this 
variation. — Locality  :  Uncertain. 


182     HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE    SOUTH-WEST   PACIFIC^ 

Lagena  laevigata  Reuss  sp.  var. 

Lagena  laevigata  Reuss  sp.  var.  Sidebottom,  1912,  Journ.  Q.  M.  0.T 
p.  400,  pi.  17,  fig.  7. 

+  P1.  17,  fig.  7.     Very  rare.— Locality  :  Nos.  15,  34. 

Lagena  acuta  Reuss  sp.  (PI.   16,  fig.  7). 

Fissurina  acuta  Reuss,  1862,  p.  340,  pi.  7,  fig.  90,  and  F.  apiculatar 
p.  339,  pi.  6,  fig.  85. 

Lagena  acuta  (including  such  as  have  only  the  slightest  indica- 
tion of  the  apiculate  process)  is  found  at  almost  all  the  localities.. 
The  size  and  inflation  of  the  tests,  as  well  as  their  outlines,  vary 
greatly. — Two  at  No.  14. 

Lagena  acuta  Reuss  sp.  var.  (PI.  16,  fig.  8). 

The  chief  feature  of  this  variety  is  the  curious  oval  marking  at- 
the  base,  on  both  sides  of  the  test.  It  is  very  rarely  so  clearly- 
shown  as  in  the  drawing.  The  tests  are  opaque  or  nearly  so,  and 
when  the  shell-substance  becomes  very  dense  the  markings 
disappear,  but  if  damped  some  trace  of  them  can  be  detected. — 
Locality  :  Nos.  3-7,  9-11,  13  15,  29,  33,  34,  39,  40,  42,  44. 

+  P1.  17,  fig.  9.  The  mixing  of  this  form  wTith  that  of  fig.  10' 
prevents  me  from  giving  the  exact  localities,  but  it  is  evidently 
rather  rare.  They  correspond  with  the  Fissurina  apiculata  Reuss,. 
1862,  p.  339,  pi.  6,  fig.  85. 

Lagena  acuta  Reuss  sp.  var.  virgulata  Sidebottom. 

Lagena  acuta  Reuss  sp.  var.  virgulata  Sidebottom,   1912,   Journ.. 
Q.M.  C,  p.  401,  pi.  17,  fig.  10. 

+  P1.  17,  tig.  10.  This  appears  to  occur  at  nearly  all  the 
stations  up  to  No.  22,  after  which  it  is  extremely  rare. 

Lagena  acuta  Reuss  sp.  var. 

Lagena  acuta  Reuss  sp.  var.  Sidebottom,  1912,  Journ.  Q.  M.  C^ 
p.  401,  pi.  17,  fig.   11.— 

Locality :  Nos.  3,  4,  6,  10,  11,  14,  24,  25,  34,  39. 


HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     183 

Lagena  lucida  Williamson  sp.   (PI.   16,  rig.   9). 

K iitosolenia  marginata  var.   lucida  Williamson,  1848,  p.  17,  pi.  2, 
fig.  17. 

There  are  nine  examples  which  are  nearly  circular  in  outline., 
and  subcarinate.  —  Locality  :  No.  44. 

PL  16,  fig.  9.  I  believe  this  to  be  an  elongate  form  of  L.  lucida, 
in  which  the  characteristic  markings  are  only  feebly  represented. 
The  shell  is  very  little  compressed.  Two  or  three  specimens  only 
oocur. — Locality  :  Uncertain. 

One  or  two  tests  are  present  which  are  intermediate  between 
the  type  and  the  elongate  form  referred  to  above.  Several  are 
apiculate.— Locality :  Nos.  1,  6,  14,  21,  22,  24,  38,  42,  43. 

Lagena  multicosta  Karrer  sp. 

Fissurina  multicosta  Karrer,  1877,  p.  379,  pi.  16  6,  fig.  20. 
Fissurina  bouei  Karrer,  p.  378,  pi.  16  6,  fig.  19. 

The  examples  are  small,  and  some  are  without  the  irregularity 
of  the  costae  characteristic  of  the  type. — Locality :  Nos.  24,  29,  34, 
35,  39,  42-44,  and  one  or  two  of  the  earlier  stations. 

Lagena  fasciata  Egger  sp.  (PI.  16,  figs.  10-13). 
Oolina  fasciata  Egger,  1857,  p.  270,  pi.  5,  figs.  12-15. 

PI.  16,  fig.  10.  Beautiful  specimens  occur  which  have  the  mouth 
protruding,  and  the  orifice  composed  of  a  line  of  pores.  The 
bands  are  flush  or  nearly  so.  Large  and  small  tests  are  on  the 
slide. — Locality:  Nos.  1,  3-5,  7,  10,  22,  44,  and  several  other 
stations  which  are  uncertain. 

PI.  16,  fig.  11.  An  apiculate  form  wrhich  is  extremely  rare. 
The  edge  of  the  test  is  flattened,  and  has  a  very  fine  groove 
running  down  its  centre.  The  orifice  appears  to  be  composed  of  a 
line  of  pores. — Locality  :  Uncertain. 

PI.  16,  fig.  12.  Slightly  apiculate,  the  orifice  large,  and  the 
entosolenian  tube  divided  at  the  end.  The  edges  of  the  bands, 
which  are  not  interrupted  at  the  base,  appear  to  be  somewhat 
raised.  When  the  test  is  opaque  it  is  difficult  to  make  out  the 
bands. — Locality  :  Nos.  24,  34,  36,  43,  44  :  frequent  at  No.  44. 

PI.  16,  fig.  13.  The  test  is  apiculate  and  the  opaque  bands 
which  appear  to  be  flush  with  the  surface  are  continuous — that  is,. 


184    HENRY    SIDEBOTTOM   ON    LAGENAE   OF  THE   SOUTH-WEST   PACIFIC. 

not  interrupted  at  the  base  as  is  usual  in  the  type-form.     About 
thirty  specimens  on  the  slide. — Locality ;  Nos.  42-44. 

Lagena  fasciata  Egger  sp.  var.  spinosa  Sidebottom. 

Lagena  fasciata  Egger  sp.  var.  spinosa  Sidebottom,  1912,  Journ. 
Q.  M.  C,  p.  402,  pi.  17,  figs.  16,  17. 

"*"P1.  17,  fig.  16.  One  or  two  small  specimens. — Locality: 
Uncertain. 

+  P1.  17,  fig  17.  A  fair  number  are  present,  but  they  are 
mixed  with  L.  staphyllearia,  so  I  cannot  give  the  localities.  See 
remarks  *  p.  402. 

Lagena  fasciata  Egger  sp.   var.  carinata  Sidebottom  (PI.   16, 

figs.   14-16). 

Lagena  fasciata  Egger  sp.  var.  carinata  Sidebottom,  1906,  Mem. 

Pro.  Lit.  Phil.  Soc,  Manchester,  No.  5,  p.  7,  pi.  1,  fig.  17. 
Lagena  fasciata  Egger  sp.  var.  carinata  Sidebottom,  1912,  Journ. 

Q.  M.  6\,  p.  403,  pi.  17,  fig.  18. 

Pi.  16,  fig.  14.  The  test  is  compressed,  and  the  keel  becomes 
more  pronounced  as  it  approaches  the  base  of  the  shell.  The 
internal  tube  is  attached  to  the  back  of  the  test.  A  few  of  the 
examples  are  very  fine,  like  the  one  chosen  for  illustration.  The 
curved  bands  seem  to  be  nothing  more  than  an  innumerable 
number  of  pores  showing  distinctly.  In  some  of  the  smaller 
examples  these  bands  can  hardly  be  distinguished.  It  is  open  to 
question  if  these  forms  and  the  following  (PI.  16,  fig.  15)  would  not 
be  better  placed  under  L.  marginata. — Locality  :  Nos.  1-3,  5-7, 
10,  11,  13  22. 

PI.  16,  fig.  15.  Test  compressed,  carinate.  The  entosolenian 
tube  is  long  and  curled  at  its  end.  The  bands  are  faintly  marked 
as  in  the  preceding  form. — Locality  :  Nos.  2-5  ;  common  at  No.  2. 

PI.  16,  fig.  16.  A  solitary  example.  The  edges  of  the  curved 
bands  are  very  slightly  raised,  and  the  shell  becomes  more  com- 
pressed as  the  orifice  is  approached.  The  keel  is  represented  by  a 
fine  ridge  only.  The  specimen  is  not  in  a  very  good  condition, 
opaque  patches  interfering  with  the  definition  of  the  bands, 
especially  at  their  bases. — Locality  :  No.  42. 

+  PI.  17,  fig.  18.  Two  or  three  examples  found.  The  carina  is 
not  pointed  at  the  base  as  in  the  figure  referred  to.— Locality  : 
Uncertain. 


HENRY    S1DEB0TT0M    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     185 

Lagena  staphyllearia  Schwager  sp. 
Fissurirta  staphyllearia  Schwager,  1866,  p.  209,  pi.  5,  fig.  24. 

The  non-carinate  form  is  rare.  The  number  of  spines  varies. 
The  tube  is  attached  to  one  side,  thus  causing  the  orifice  to  be 
eccentric.  In  a  few  instances  of  the  carinate  variety,  where  only- 
two  spines  are  present,  it  is  impossible  to  separate  them  from  the 
Fissurina  bicaudata  Seguenza,  which  is  generally  placed  with  L. 
man/biota.—  Locality  ■  Nos.  1-7,  9-12,  15-25,  29,  33,  34,  36,  37, 
39-43. 

The  variety  with  either  the  ketl  or  the  lower  part  of  the  test 
serrated  or  partially  fimbriated  is  not  so  frequent,  but  occurs  at 
many  localities.  The  orifice  is  central  and  the  sides  of  the  test 
are  only  slightly  carinate. — Locality  :  Nos.  5-8,  10,  11,  14,  15,  18, 
19,  21,  22,  24,  33,  34,  40,  43. 

+  P1.  17.  fig.  19.     Very  rave.— Locality  :  Nos.  2,  3,  15,  22. 

+  P1.  17,  fig.  21.  This  peculiar  variety  is  rather  rare.  The 
tests  are  semi-opaque.  There  is  a  short  entosolenian  tube. — 
Locality :  Nos.  5-11,  13,  21,  23,  25,  36,  39,  40. 

+  P1.  17,  figs  22,  23.  See  remarks  *  p.  403. — Locality:  Nos. 
4-6,  8,  10,  22,  23,  33,  39. 

Lagena  staphyllearia  Schwager  sp.  var.  quadricarinata 

Sidebottom. 

Lagena  staphyllearia  Schwager  sp.  var.  quadricarinata  Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.   404,   pi.    21,  fig.  16. 

Locality  .-  Nos.  2,  5-7,  9,  10,  12,  13,  21,  38,  41. 

Lagena  unguiculata  Brady. 

Lagena  unguiculata  Brady,  1881.  Quart.  Journ.  Micr.  Sci.,  vol.  21, 

(N.S.),  p.  61. 
-Lagena  unguiculata  Brady,  1884,  p.  474,  pi.  59,  fig.  12. 

See  remarks  +  p.  404. — Locality  :  Nos.  5-10. 

Lagena  quadrata  Williamson  sp. 
-Entosolenia marginata  var.  quadrata  Williamson,  1858,  p.  11,  pi.  1, 
fig.  27. 
Both  the  carinate  and  non-carinate  form  are  present. — Locality  : 
Nos.  15,  22,  24,  25,  34,  37,  40,  42-44. 

Journ.  Q.  M.  C,  Series  II.— No.  73.  13 


186    HENRY   SIDEBOTTOM   ON    LAGENAE   OF   THE    SOUTH-WEST   PACIFIC. 

There  are  several'  examples  which  have  a  short  neck  and  the 
orifice  carrying  a  short  spine  at  either  side.  Three  or  four 
specimens  are  similar  to  the  one  figured  by  Mr.  Millett  in  his 
Malay  Report,  1901,  p.  496,  pi.  8,  fig.  18. 

Lagena  marginata  Walker  and  Boys  sp.  (PI.  16,  figs.  17-20, 

fig.   18,  trifacial  form). 

" Serpula    {Lagena)   marginata"   Walker  and  Boys,  1784,  p.  2,. 
pi.  1,  fig.  7. 

This  species  is  exceedingly  well  represented  in  these  gatherings, 
and  in  one  form  or  another  is  found  at  nearly  all  the  stations. 
The  shape  of  the  body  of  the  test  varies  from  flattened  to  globular, 
and  in  outline  from  circular  to  elongate-pyriform,  the  carination 
from  a  fine  ridge  to  a  very  broad  wing.  The  situation  and  form 
of  the  orifice  are  variable.  Apiculate  examples  are  present  and 
some  have  the  keel  acuminate  at  the  base. 

PI.  16,  fig.  17.  This  agrees  fairly  well  in  outline  with  Fissurina 
paradoxa  Seguenza,  1862,  pi.  2,  fig.  7.  The  Fissurina  bicaudata 
Seguenza,  1862,  pi.  2,  fig.  16,  is  also  represented,  and  it  is  difficult 
in  some  cases  to  separate  this  from  L.  staphyllearia. 

PI.  16,  fig.  18.  A  trifacial  form.  If  anything,  the  three  faces 
of  the  body  are  somewhat  concave  ;  one  would  rather  expect  them 
to  be  convex,  judging  from  trifacial  examples  that  occur  in  other 
species.  The  specimens  vary  very  little. — Locality  ;  Nos.  2-4, 
8-10,  14,  15,  22,  29,  34,  36,  39,  40. 

PI.  16,  fig.  19.  The  edge  of  the  test  is  flattened,  the  orifice 
fissurine.  In  some  positions  it  has  the  appearance  of  being 
slightly  bicarinate,  but  I  do  not  think  it  is  so. — Locality :  Nos. 
42,  43. 

PI.  16,  fig.  20.  This  minute  variety  has  a  comparatively  large 
orifice,  which  is  much  compressed  and  opens  out  on  one  side  of 
the  median  line  ;  the  tube  is  attached  to  the  back  of  the  test, 
which  is  very  slightly  carinate.  The  test  is  moderately  com- 
pressed and  curiously  tucked  in  at  its  base.  The  specimens  are 
mixed  with  others  very  similar  to  them,  but  which  have  the 
orifice  central  and  the  tube  short  and  straight.  There  are  other 
forms  on  the  same  square,  so  I  cannot  give  the  exact  localities. 
The  two  forms  mentioned  are  rare.  Both  were  found  at  a  station 
later  in  the  series  than  ISTo.  22. 


HENRY   SIDEBOTTOM    ON   LAGENAE   OF  THE   SOUTH-WEST   PACIFIC.     187 

Lagena  compresso-marginata  Fornasini  (PI.   16,  fig.  21). 

Lagena  compresso-marginata  Fornasini,  1889,  Minute  Forme  di 
Riz.  Retic.  nella  Mama  Plioc.  del  Ponticello  di  Savena, 
Bologna,  fig.  16. 

PI.  16,  fig.  21.  This  is  rather  a  stoutly-built  form.  The  aperture 
is  fissurine  and  the  test  apiculate. — Locality  :  Nos.  22,  24. 
Rather  rare. 

There  are  a  few  very  small  examples  that  appear  to  be  almost 
identical  with  Fornasini's  figure. — Locality  :  Uncertain. 

+  PI.  17,  fig.  30.  Only  two  or  three  found. — Locality:  Nos. 
42,  44,  and  two  or  three  examples  at  one  or  two  other  stations. 

+  PI.  17,  fig.  31.     Very  rave.  — Locality  ;  Nos.  2,  4. 

***  PI.  18,  fig.  1.  Very  rare.  See  remarks  +  p.  406. — Locality  ; 
Nos.  2,  5,  7,  19,  24. 

Lagena  marginata  Walker  and  Boys  var. 

Lagena    marginata    Walker    and    Boys    var.    Sidebottom,    1912, 
Journ.  Q.  M.  C,  p.  407,  pi.  18,  figs.  4,  5. 
Locality:  Nos. 4-6,  10-13,  16, 17,  19-23,  25,  36,  40. 

Lagena  marginata  Walker  and  Boys  var.  catenulosa  Chapman 

(PL  16,  fig.  22). 

Lagena  marginata  var.  catenulosa  Chapman,  1895,  p.  28,  pi.  1,  fig.  5. 

Lagena  marginata  Walker  and  Boys  var.  catenulosa  (Chapman) 

Sidebottom,  1912,  Journ.  Q.  M.  C,  p.  407,  pi.  18,  fig.  6. 

PI.  16,  fig.  22.  Four  examples  occur.  The  one  chosen  for 
illustration  hardly  shows  a  trace  of  the  chain-pattern,  and  the 
test  is  free  from  exogenous  shell-growth.  The  others  show  the 
chain-pattern.  One  of  the  specimens  has  the  body  of  the  test 
covered  with  exogenous  beads.  The  few  tubuli  shown  in  the 
drawing  are  caused,  I  believe,  by  the  borings  of  some  animal. — ■ 
Locality  :  Nos.  1,  5,  10. 

Lagena  marginata  Walker  and  Boys  var.  raricostata 

Sidebottom. 

Lagena  marginata  Walker  and  Boys  var.  raricostata  Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.  408,  pi.  18,  figs.  8,  9. 

*'r  PI.  18,  fig.  8.  Over  twenty  specimens  are  on  the  slide. — 
Locality  :  Nos.  1-3. 


18S    HENRY   SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC. 

Lagena  marginata  Walker  and  Boys  var.  striolata  Sidebottom. 

Lagena  marginata  Walker  and   Boys  var.  striolata  Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.  408,  pi.  18,  figs.  10,  11. 

+  P1.  18,  fig.  10.— Locality:  Nos.  1,  3,  4,  15,  18-20,  22-25,  34, 
35,  38,  42-44  ;  frequent  at  Nos.  42,  43. 

+  PI.  18,  fig.  11.— Locality  :  Nos.  23,  24,  42. 

Lagena  marginata  Walker  and  Boys  var.  elegans  Sidebottom. 

Lagena    marginata   Walker    and    Boys  var.   elegans   Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.  409,  pi.  18,  fig.  12. 

Locality  :  Nos.  14,  19,  20  ;  frequent  at  No.  14. 

Lagena  marginata  Walker  and  Boys  var.  retrocostata 

Sidebottom. 

Lagena  marginata  Walker  and  Boys  var.  retrocostata  Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.  409,  pi.  18,  fig.  13. 

Locality  :  One  specimen  at  No.  2,  and  one  other,  station  un- 
certain. 

Lagena  marginata  Walker  and  Boys  var.  semimarginata 

Reuss. 

Lagena  No.  64,  von.  Schlicht,   1870,  p.    11,  pi.   4,  figs.   4-6;  and 

Xo.  65,  p.  11,  pi.  4,  figs.  10-12. 
Lagena  marginata  var.  semimarginata  Reuss,  1870,  p.  468. 

An  altogether  unsatisfactory  variation.  It  occurs  in  several 
forms  at  a  few  stations  ;  that  figured  in  the  Challenger  Report, 
pi.  59,  fig.  19,  occurs  at  No.  44. 

Lagena  marginata  Walker  and  Boys  var.  seminiformis 

Sch  wager. 

Miliola  stiligera  Ehrenberg  (?)  1854,  pi.  31,  fig.  6. 
Lagena  seminiformis  Schwager,  1866,  p.  208,  pi.  5,  fig.  21. 

Four  large  examples  occur,  similar  to  those  figured  in  the 
Challenger  Report,  pi.  59,  figs.  28-30. — Locality;  Nos.  5, 16, 17. 


HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST    PACIFIC.     189 

"*"  PI.  18,  fig.  16.  Extremely  rare,  only  one  or  two  being  found. 
— Locality ;  Uncertain. 

"i"  PI.  18,  fig.  17. — Locality-.  Nos.  1-3,  15.  Three  examples  at 
two  or  perhaps  three  of  the  four  stations  indicated  ;  also  six  at  a 
few  other  uncertain  localities. 

+  PI.  18,  fig.  18. — Locality:  Nos.  1,  3,  13,  and  several  others. 
Very  rare. 

**■  PI.  18,  fig.  19.  Several  have  the  central  spine  at  the  base  of 
the  same  length  as  the  other  two. — Locality  :  Nos.  2,  3,  6-8,  10, 
11,  24,  34-36. 

Lagena  marginato-psrforata  Seguenza  (PI.   16,  figs.  23-25). 
Lagena  marglaato-perforata  Seguenza,  1880,  p.  332,  pi.  17,  fig.  34. 

Very  numerous.  The  variety  with  no  keel  is  rare.  The  shape 
of  the  test  varies  a  good  deal  as  regards  compression  and  length. 
In  a  few  cases,  fine  lines,  running  the  length  of  the  test,  make 
their  appearance.  At  the  edge  of  the  test,  the  markings  are 
sometimes  arranged  in  a  line. — Locality  :  Nos.  1,  2,  4,  5,  7-15,  19, 
20,  22-25,  29,  38-40,  42-44. 

PI.  16,  fig.  23.  This  is  nearly  circular  in  section  near  the  base, 
and  becomes  compressed  as  the  orifice  is  approached.  Tube 
straight.     Ptare. — Locality  :  No.  14. 

PI.  16,  fig.  24.  In  this  example  fine  pores  are  seen,  but  with 
few  exceptions  the  centre  of  each  face  of  the  test  is  free  from 
them.  One  specimen  is  in  the  trifacial  condition. — Locality  ; 
Nos.  23-25,  29,  33,  36,  38,  39. 

PI.  16,  fig.  25.  Test  well  compressed,  subcarinate.  Except  for 
the  two  lines  of  pores  that  run  round  the  test  close  to  its  edge, 
the  faces  are  almost  free  from  them.  The  shell  is  partially 
clouded.     Fairly  frequent. — Locality  :  Uncertain. 

Lagena  Wrightiana,  Brady. 

Lagena  Wrightiana  Brady,  Quart.  Journ.  Micr.  ScL,  vol.  21,1881, 

p.  62. 
Lagena  Wrightiana  Brady,  1884,  p.  482,  pi.  61,  figs.  6,  7. 

The  central  part  of  the  faces  of  the  test  is  not  always  smooth. 
Very  rare. — Locality  :  Nos.  37,  42,  43. 


190    HENRY   SIDEBOTTOM   ON   LAGENAE   OF  THE   SOUTH-WEST   PACIFIC. 

Lagena  lagenoides  Williamson  sp.  (PI.   16,  figs.  26-29,  and 

pi.   17,  fig.   1). 

Entosolenia      marginata     Walker     and      Boys     var.     lagenoides 
Williamson,  1858,  p.  11,  pi.  1,  figs.  25,  26. 

This  and  its  numerous  variations  are  well  represented.  PI.  16, 
figs.  26,  27.  I  was  tempted  to  place  these  under  L.  marginata, 
but  the  appearance  of  the  wing  caused  me  to  hesitate  and  to 
submit  a  specimen  to  Mr.  Earland  for  examination.  He  reported 
that  the  wing  was  tubulated,  being  "  infiltrated  with  amorphous 
carbonate  of  lime  subsequent  to  the  death  of  the  animal."  Mr. 
Millett  considers  that  if  tubuli  are  present  "  their  affinity  would 
be  with  L.  lagenoides  rather  than  with  L.  marginata."  Besides 
the  two  forms  figured,  both  large  and  small  circular  examples 
occur  in  the  same  condition,  only  with  the  tubuli  showing  more 
plainly. 

PI.  16,  fig.  28  represents  one  of  the  small  examples.  There  are 
also  specimens  which  are  apparently  of  exactly  the  same  form,  in 
which  the  tubuli,  if  present,  must  be  extremely  minute.  It  would 
appear  therefore  necessary  to  submit  all  such  forms  to  critical 
examination. — Locality :  Nos.  5-7,  11,  14,  15,  18-22. 

PI.  16,  fig.  29.  In  this  instance  the  keel  is  twisted  at  the  base. 
Four  specimens  found. — Locality  :  Uncertain,  but  after  station 
No.  22. 

PI.  17,  fig.  1.  The  test  is  well  compressed  and  the  orifice  also. 
Entosolenian  tube  short  and  curled.  —Locality :  Ncs.  42-44 ; 
frequent  at  Nos.  43,  44. 

+  P1.  18,  fig.  22.  The  form  occurring  is  very  similar  to  the 
figure  referred  to.  It  is  rather  smaller  and  the  keel  is  narrower 
and  thicker  ;  the  neck  and  phialine  orifice  are  the  same. — Locality  ; 
Nos.  1-3,  42-44. 

Six  large  specimens  similar  to  the  Challenger  Report  figure, 
pi.  60,  fig.  14,  are  also  present.  Very  rare. — Locality  :  Nos.  2, 
22,  24. 

Another  set  is  similar  to  +pl.  19,  fig.  4,  but  the  tests  are  not 
striated.     Frequent. — Locality  :  Nos.  2-8,  11. 

+  PI.  18,  fig.  23.  See  remarks,  +p.  412.— Locality  :  Nos.  2,  36, 
38,  39. 

+  P1.   18,   fig.   29.     Typical  examples  are  very  rare  and  not  so 


HENRY   SIDEBOTTOM    OX    LAGENAE    OF   THE   SOUTH-WEST   PACIFIC.     191 

large  as  the  specimen   referred  to. — Locality :  No.   3,  and  either 
No.  35  or  39. 

Besides  the  above,  there  are  a  few  specimens  which  are  much 
smaller,  especially  in  the  width  of  the  test. — Locality :  Nos.  17, 
19,  and  one  or  two  other  stations. 

Lagena  lagenoid.es  Williamson  sp.  var.  nov.  duplicata 

(PI.   17,  fig.  2). 

The  test  is  bicarinate  ;  aperture  oval  and  the  keels  tubulated. 
Six  specimens  found. — Locality  :  Nos.  24,  37. 

Lagena  lagenoides  Williamson  sp.  var.  tenuistriata  Brady. 

Lagena   tubulifera  var.   tenuistriata   Brady,   1881,  Quart.   Joiirn. 

Micr.  Sci.  vol,  21  (N.S.),  p.  61. 
Lagena  lagenoides  Williamson  var.  tenuistrata  Brady,  1884,  p.  479, 

pi.  60,  figs.  11,  15,  16. 

*P1.  19,  fig.  4.  Very  frequent.  These  correspond  to  the 
Challenger  Report,  pi.  60,  fig.  11.  The  trifacial  form  also  occurs. 
—Locality ;  Nos.  1-11,  13,  14, 17,  21-24,  29,  31,  33-35,  37,  39-41. 

There  is  another  set  of  specimens  which  are  not  quite  so  large 
and  have  the  costae  on  the  body  of  the  test,  farther  apart. — 
Locality :  Nos.  14,  15,  17,  18. 

There  are  a  few  large  specimens  very  similar  to  the  Challenger 
Report,  pi.  60,  fig.  15.  In  the  stouter  examples  the  fine  costae 
■coalesce  to  such  an  extent  that  the  surface  has  a  pitted  appear- 
ance.— Locality:  Nos.  2,  8,  11,  and  one  or  two  other  stations. 

Lagena  formosa  Schwager  (PI.   17,  figs.  3-7). 

Lagena  formosa  (pars)  Schwager,  1866,  p.  206,  pi.  4,  fig.  19. 
Lagena  formosa  (Schwager)  Brady,   1884,  p.  480,  pi.  60,  figs.  10, 
18-20. 

This  is  present  in  many  forms  ;  some  show  the  raised  border 
punctate,  others  do  not.      See  remarks  **"  p.  414. 

PI.  17,  fig.  3.  In  this,  which  is  obviously  of  the  same  kind  as 
fig.  18,  pl.  60,  in  the  Challenger  Report,  the  raised  border  is 
absent.  Others  agree  with  this  figure,  also  with  the  Challenger 
Report,  fig.  20. 

Several  very  fine  specimens  are  intermediate  between  fig.  18 
and    L.  formosa  var.  favosa  Brady,  on  the  same  plate,  fig.   21. 


192    HENRY    SIDEBOTTOM    ON    LAGENAE  OF   THE    SOUTH-WEST   PACTFIC 

They  are  heavily  punctate  at  the  base  of  the  neck,  and  costae  just 
start  to  run  clown  the  keels.  Many  small  examples  occur,  which 
come  under  this  unsatisfactory  species,  but  as  they  are  mixed  on 
the  various  squares  I  can  only  give  the  stations  for  the  whole 
series.— Locality :  Nos.  1-8,  10,  11,  13,  14,  17,  21,  23-25,  29, 
37,  39-41,  43. 

PI.  17,  fig.  4.  The  keel  splits  near  the  top,  and  the  space  thus 
formed  is  filled  with  shell-growth.  The  specimens  are  not  in  a 
satisfactory  condition  for  examination,  so  I  cannot  say  if  the 
tubuli  in  the  keel  occupy  the  whole  of  the  space.  The  punctate 
border  does  not  seem  to  be  raised,  and  it  shows  clearer  in  substance 
than  the  rest  of  the  test.  I  believe  this  is  the  same  as  Challenger 
Report,  pi.  60,  fig.  10.— Locality :  No.  44. 

PI.  17,  fig.  5.  T  am  inclined  to  believe  that  the  keel  has  broken 
away  in  these  specimens,  of  which  there  are  seven.  They  are  all 
in  the  same  condition ;  the  drawing  shows  how  the  keel  has 
begun  to  split. — Locality .•  Nos.  43,  44. 

+  PI.  18,  fig.  24.  I  am  now  inclined  to  believe  that  in  this 
case  also  the  keel  has  become  fractured. 

PI.  17,  fig.  6.  This  has  a  likeness  to  the  preceding  pi.  17,  fig.  5. 
The  keel,  which  commences  at  the  neck,  soon  splits  and  joins  the 
two  borders  ;  the  space  between  them  is  filled  with  shell-growth. 
The  test  has  a  very  compact  look  and  the  tubuli  show  clearly. 
Rare. — Locality  :  Nos.  42,  43. 

PI.  17,  fig.  7.  A  solitary  specimen  in  good  condition.  The  keel, 
commencing  at  the  orifice,  dies  away  about  half-way  down  the 
test.  A  few  well-marked  pores  are  scattered  on  each  face  of  the 
test.     At  the  base  are  several  short  costae. — Locality  ;  No.  37. 

+  P1.  19,  fig.  9.  See  remarks,  +  p.  414.  Frequent. — Locality : 
Nos.  1,  2,  10,  11,  14,  17-19,  22.  Over  twenty  examples  occur  after 
station  No.  22,  but  the  exact  stations  are  uncertain. 

Lagena  formosa  Sch wager,  var.  (PI.  17,  fig.  8). 

The  drawing  of  this  variety  must  be  taken  more  or  less  as 
diagrammatic.  The  test,  which  has  three  keels  (the  central  one 
commencing  at  the  aperture)  is  in  an  opaque  condition.  The 
spaces  between  the  keels  are  filled  with  shell-growth.  The  tubuli 
hardly  show,  unless  the  shell  be  moistened.  The  body  of  the  test 
has  fine  costae  running  lengthwise,  and  is  finely  pitted.     There* 


HENRY   SIDEBOTTOM    ON    LAGEXAE   OF   THE   SOUTH-WEST   PACIFIC.     193 

are  only  two  specimens  and  they  are  exactly  alike. — Locality  .- 
No.  40. 

Lagena  formosa  Schwager  var.  comata  Brady. 
Lagena formosa  var.  comata  Brady,  1884,  p.  480,  pi.  60,  tig.  22. 

A  few  large  specimens  occur  very  similar  to  the  Challenger 
examples,  pi.  60,  tig.  22. — Locality :  Nos.  5,  6,  33,  34. 

+  P1.  19,  fig.  11.     A  single  example.  —  Locality:  Uncertain. 

+  P1.  19,  fig.  12.  Very  rare.— Locality :  Nos.  6,  10,  22,  and 
one  or  two  stations  which  are  uncertain. 

Lagena  squamoso-alata  Brady  (PI.   18,  fig.  20). 

Lagena   squamoso-alata  Brady,    1881,    Quart.    Journ.    Jlicr.    Sci. 

vol.  21  (N.S.),  p.  61. 
Lagena  squamoso-alata  Brady,  1884,  p.  481,  pi.  60,  fig.  23. 

A  single  example  occurs,  which  is  typical,  except  that  the 
produced  neck  is  absent,  having  most  probably  been  broken  off. — 
Locality  :  No.  23. 

PI.  18,  fig.  20.  Besides  the  above  typical  specimen,  there  are 
twenty-two  tests  which  are  smaller  and  not  so  robust.  They 
answer  to  Brady's  description  of  the  species.  The  pittings  on  the 
body  of  the  test  have  a  tendency  at  times  to  arrange  themselves 
in  lines.  The  raised  border  appears  to  be  punctate.  It  is 
difficult  to  make  out  the  markings  on  the  wings,  owing  to  debris, 
but  they  can  be  detected  in  some  of  the  specimens.  I  believe  the 
wings  to  be  cellulated.  Brady,  in  the  Challenger  Report,  only 
mentions  that  they  have  radiate  markings  ;  but  on  examining  the 
edges  of  my  typical  specimen  it  is  apparent  that  the  wings  are 
cellulated.  I  take  this  form  to  be  simply  a  variety  of  L.  formosa. 
One  example  is  in  the  trifacial  condition. — Locality  ;  Nos.  24,  25, 
34,  36. 

Lagena  quadrangularis  Brady. 

Lagena  quadrangularis  Brady,  1884,  p.  483,  pi.  114,  fig.  11. 
Lagena    quadrangularis  (Brady)   Millett,    1901,   p.    625,   pi.    14, 
%  IT. 

A  single  typical  specimen,  but  the  neck  appears  to  be  fractured. 
— Locality ;  Either  No.  14  or  No.  22. 


194    HENRY   SIDEBOTTOM   ON    LAGENAE   OF  THE   SOUTH-WEST   PACIFIC. 

Lagena  Orbignyana  Seguenza  sp.  (PI.   17,  figs.  9-11). 

Entosolenia  mdrginata  (pars)  Williamson,  1858,  p.  10,  pi.  1,  figs. 

19,  20. 
Fissurina  Orbignyana  Seguenza,  1862,  p.  66,  pi.  2,  figs.  25,  26. 

This  occurs  in  many  forms.  Some  of  the  specimens  are  similar 
to  the  Challenger  Report,  pi.  59,  figs.  25,  26.  Numerous  small 
varieties  also  are  present.  In  some  the  side  keels  are  little  more 
than  slightly  raised  ridges. 

PI.  17,  fig.  9.     This  is  a  very  neat  and  compact  variety. 

The  test  is  moderately  compressed. — Locality :  Nos.  42-44 ; 
frequent  at  Nos.  42,  44. 

PI.  17,  fig.  10.  I  take  this  to.be  a  variety  of  L.  Orbignyana,  in 
which  the  central  keel  has  split  soon  after  leaving  the  orifice. 
The  body  of  the  test  is  much  compressed,  and  is  roughened.  The 
entosolenian  tube  is  long  and  attached.  The  split  keel  is  entirely 
blocked  wTith  debris,  or  shell-growth.  Two  examples  found. — 
Locality :  No.  38. 

PI.  17,  fig.  11.  A  neat  form.  The  central  keel  is  emarginate 
at  the  base,  at  the  middle  of  which  one  or  two  small  spines 
project.  The  two  subsidiary  keels  are  not  generally  continuous. 
There  are  over  one  hundred  specimens. — Locality  :  Nos.  1,  2,  4-13, 
21,  23,  26,  29,  33,  34,  38,  39. 

Lagena  Orbignyana  Seguenza  sp.  var.  lacunata  Burrows  and 

Holland  (PI.  17,  fig.  12). 

Lagena  lacunata  (Burrows  and  Holland)  Jones,  1895,  p.  205,  pi.  7, 
fitf   12 

One  set  agrees  exactly  with  fig.  1,  pi.  60  of  the  Challenger 
Report,  which  Messrs.  Burrows  and  Holland  point  out  in  the 
above  reference,  is  misnamed  as  L.  castrensis  Sch wager. — Locality  : 
Nos.  42-44 ;  frequent  at  No.  44. 

A  few  small  examples  are  occasionally  met  with  in  which  the 
pittings  are  numerous  and  minute,  and  the  keels  very  feebly 
developed. — Locality  :  Uncertain. 

PI.  17,  fig.  12.  I  am  treating  this  as  a  form  of  X.  Orbignyana 
var.  lacunata,  but  it  appears  to  have  one  of  the  characteristics  of 
L.  annectens  (Burrows  and  Holland)  Jones,  1895,  for  the  band 
round  the  body  of  the  test  appears  to  be  very  slightly  concave. 


HENRY    SIDEBOTTOM    ON    LAGENAE    OF  THE   SOUTH-WEST   PACIFIC.     195 

The  edges  of  the  band  are  just  raised  above  the  surface,  and  the 
space  between  is  roughened.  It  will  be  noticed,  by  reference  to 
the  Challenger  figure,  pi.  60,  fig.  1,  that  there  is  a  ridge,  or  minor 
keel,  between  the  side  keel  and  the  central  one,  and  I  take  my 
specimens  to  be  in  the  same  condition,  only  the  inner  ridge  is 
quite  close  to  the  central  keel.  The  body  of  the  test  is  finely 
pitted  all  over.  The  aperture  is  large,  compressed  and  lipped. 
In  two  cases  the  keel  is  serrated  all  round,  but  it  is  doubtful  if 
this  is  natural.  The  tube  is  attached.  Frequent. — Locality  : 
Nos.  42,  43. 

Lagena  Orbignyana  Seguenza  sp.  var.  Walleriana  Wright. 

Lagena  Orbignyana  sp.  var.  Walleriana  Wright,  1886, Proc.  JR.  Irish 
Acad.,  ser.  2,  vol.  iv.,  p.  611,  and  1891,  p.  481,  p.  20,  fig.  8. 

In  all  the  specimens  the  typical  boss  is  replaced  by  a  ring, 
which  is  very  slightly  raised. — Locality:  Nos.  2,  22,  and  one  or 
more  of  the  three  stations,  Nos.  42-44. 

Lagena  Orbignyana  Seguenza  sp.  var.  unicostata  Sidebottom. 

Lagena    Orbignyana    Seguenza    sp.    var.    unicostata    Sidebottom, 
1912,  Journ.  Q.  M.  C,  p.  417,  pi.  19,  fig.  22. 

The  single  costa  in  this  case  runs  the  whole  length  of  the  body 
of  the  test.     Very  rare. — Locality  ;  Nos.  18,  22. 

Lagena  Orbignyana  Seguenza  sp.  var.  pulchella  Brady 

(PI.  17,  fig.  13). 

Lagena  pulchella  Brady,   1866,  Rept.  Brit.  Assoc.   (Nottingham), 

p.  70. 
Lagena  pulchella  Brady,  Annals  and  Mag.  Nat.  Hist.,  1870,  p.  294, 

pi.  12,  fig.  1. 

The  largest  specimens  are  very  similar  to  L.  Orbignyana  var. 
variabilis  Wright,  1891,  pi.  20,  fig.  9,  but  the  costae  are  irregular 
and  cover  the  whole  of  the  body  of  the  test ;  sometimes  there  is 
a  fine  ridge  showing  between  the  main  keel  and  the  side  keels. 
Very  rare. — Locality  :  Uncertain. 

A  smaller  set  is  frequent,  with  few  and  irregular  costae.  The 
side  keels  amount  to  little  more  than  slight  ridges. — Locality  : 
No.  44. 


196    HENRY   SIDEBOTTOM   ON    LAGENAE   OF   THE   SOUTH-WEST  PACIFIC* 

A  few  very  small  examples  are  also  present. 

PI.  17,  fig.  13.  This  solitary  example  has  the  eostae  well  raised, 
and  as  they  are  irregular  I  have  placed  it  under  the  above  head- 
ing.    The  side  keels  are  only  just  apparent.  —  Locality  :  No.  44. 

+  P1.  19,  fig.  24.  Very  rare.  See  remarks  +  p.  418. — Locality  .- 
Nos.  1,  38. 

Lagena  Orbignyana  Seguenza  sp.   var.  clathrata  Brady 

(PI.  17,  fig.  14). 

Lagena  clathrata  Brady,  1884,  p.  485,  pi.  60,  fig.  4. 

The  type-form  occurs,  but  is  always  rare,  except  at  No.  43, 
where  eleven  were  found. — Locality:  Nos.  17,  18,  24,  29,  35,  37, 
38,  43,  44. 

A  few  very  small  specimens  are  present,  but  they  are  not 
typical.  Others  are  minute,  with  numerous  fine  eostae  either 
straight  or  curved,  these  latter  resembling  L.  variabilis,  as  Mr. 
Millett  remarks  in  his  Malay  Report,  1901,  p.  628. 

PL  17,  fig.  14.  I  think  this  may  be  brought  under  the  above 
heading.  The  test  is  compressed  and  has  three  keels ;  these 
stand  out  more  than  the  three  eostae  which  run  down  each  face 
of  the  test. — Locality :  Nos.  8,  10-14  ;  frequent  at  No.  8. 

Lagena  Orbignyana  Seguenza  sp.  var.  variabilis  Wright. 

Lagena   Orbignyana  sp.   var.    variabilis  Wright,   1890,  p.  482,  pi. 
20,  fig.  9. 

Except  that  the  side  keels  are  not  so  well  developed,  and  the 
striae  are  very  numerous,  the  specimens  are  fairly  typical.  In 
several  instances  the  striae  are  inclined  to  cover  the  body  of 
the  test,  and  in  others  they  are  either  absent  or  scarcely  per- 
ceptible.— Locality .-  2,  5-7,  10-14,  16-18,  24,  29,  34,  35. 

Lagena  Orbignyana  Seguenza  sp.  var.  (PI.  17,  fig.  15). 

The  test  is  only  slightly  compressed  ;  the  main  keel,  which 
starts  at  the  orifice,  splits  as  it  approaches  the  body  of  the  test. 
Very  fine  bars  cross  the  space  thus  formed.  Between  the  cross- 
bars is  a  well-marked  circular  depression.  Besides  the  side  keels 
there  are  two  semicircular  eostae,  one  of  these  on  each  face  of 
the  test.  At  the  base  is  an  irregular  circular  projection  to  which 
the   keels   are   attached.     The    wall    of    this    projection    is   thin. 


HENRY    SIDEBOTTOM    ON    LAGENAE    OF   THE   SOUTH-WEST   PACIFIC.     197 

0 

Onlv  two  specimens  were  found,  each  of  them  badly  fractured. 
Both  have  been  utilised  in  preparing  the  illustration,  which  must 
be  considered  as  a  drawing  of  a  restored  specimen. — Locality; 
Uncertain. 

Lagena  bicarinata  Terquem  pp.  (PI.   17,  figs.  16,  17). 
Fissurina  bicarinata  Terquem,  18827  p.  31,  pl.  1  (9),  fig.  24. 

The  type-form  does  not  appear  to  be  present. 

PI.  17,  fig.  16.  The  tests  are  in  a  very  opaque  condition. — 
Locality:  Nos.  23,  24,  33,  34,  40. 

PI.  17,  fig.  17.  There  are  two  or  more  spines  at  the  base. 
Eleven  specimens  are  in  good  condition. — Locality  :  Nos.  2-3. 

+  PI.  19,  fig.  27.     See  remarks  +  p.  419.— Locality  ;  Nos.  2-4. 

A  few  also  occur,  very  similar  to  these,  except  that  the  body  of 
the  test  is  more  circular  in  outline. — Locality  :  Uncertain. 

Lagena  bicarinata  Terquem  sp.  var.  (PI.   17,  fig.  18). 

Test  bicarinate.  The  faces  of  the  test  are  slightly  convex,  and 
the  two  keels  slope  towards  their  edges,  the  effect  being  that  the 
test  appears  to  have  a  boss  on  either  face.  Orifice  much  com- 
pressed and  composed  of  a  row  of  pores.  A  solitary  specimen. — 
Locality  :  No.  37. 

Lagena  bicarinata  Terquem  sp.  var.  (PI.   17,  fig.  19). 

Test  bicarinate  and  apiculate,  with  a  row  of  very  short  tubular 
projections  running  round  the  edge  of  the  test  between  the  keels. 
The  test  becomes  more  compressed  as  the  orifice  is  approached. 
Two  examples  only  occur.  The  neck  appears  to  be  broken  olT  in 
both  cases. — Locality:  No.  43. 

Lagena  bicarinata  Terquem  sp.  var.  (PI.  17,  fig.  20). 

Test  bicarinate,  the  keels  generally  dying  away  as  they 
approach  the  orifice,  which  is  composed  of  a  series  of  fine  pores. 
I  cannot  say  if  the  fine  bands,  which  adorn  each  face  of  the  test, 
a,re  raised  or  not.  Bands  of  different  nature  and  length  are 
found  on  other  species  besides  L.  fasciata,  so  I  prefer  to  place  this 
form  under  L.  bicarinata,  instead  of  treating  it  as  L.  fasciata  in 
the  bicarinate  condition. — Locality  :  Nos.  1-10,  13,  15,  16. 


198    HENRY    SIDEBOTTOM    ON    LAGENAE   OF  THE   SOUTH-WEST    PACIFIC 

Lagena  auriculata  Brady  (PI.  17,  figs.  21,  22,  and  pi.  18, 

fig.  1). 

Lagena  auriculata  Brady,   1881,  Quart.  Journ.  Jlicr.  Sri.,  vol.  21 

(N.S.),  p.  61. 
Lagena  auriculata  Brady,  1884,  p.  487,  pi.  60,  figs.  29,  31,  33. 

This  is  largely  represented,  especially  in  its  variations  ;  inter- 
mediate forms  occur  which  it  would  be  interesting  to  figure. 

PI.  17,  fig.  21.  In  this  solitary  specimen  the  wing  has  divided 
at  a  point  a  little  above  the  body  of  the  shell. — Locality  ;  No.  2& 
or  No.  39. 

PI.  17,  fig.  22.  A  neat  form  which  appears  to  be  strongly 
built.  The  shell  is  moderately  compressed.  The  entosolenian 
tube,  when  present,  is  very  short  and  straight.  The  orifice  is 
crowned  with  a  boss,  and  the  loops  at  the  base  are  feebly 
represented.     Nine  specimens  occur. — Locality  ;  Nos.  2,  10. 

PI.  18,  fig.  1.  A  stoutly-built  form.  The  test  is  subcarinate,. 
and  the  orifice  situated  in  a  depression.  The  two  loops  at  the 
base  are  feebly  developed.  Very  rare. — Locality  ;  Uncertain,  but- 
after  station  No.  23. 

"**  PI.  20,  fig.  4.  A  few  examples  resemble  this  variation,  the 
keel  being  continuous  round  the  edge  of  the  test. — Locality :  Nos. 
23,  24,  26,  36,  38,  40,  42,  43. 

"*"  PI.  20,  fig.  5.  There  are  twelve  examples,  closely  resembling 
this  figure,  but  having  no  small  wings  at  the  top  of  the  test. — 
Locality :  Nos.  24,  29,  34,  36,  39-41. 

**"  PI.  20,  figs.  7.  8.  A  large  number  are  similar  to  these  forms 
and  to  Challenger  Report,  pi.  60,  fig.  29. — Locality  :  Nos.  2-4,. 
6-12, 17-24,  26  29,  33  35,  38  43. 

+  P1.  20,  figs.  9,  10.  Some  forms  present  lie  more  or  less 
between  the  two  figures  given  at  this  reference.  —  Locality;  Nos. 
2-6,  6-11, 17, 18,  21,  22. 

+  P1.  20,  figs.  11,  12.  Only  two  or  three  specimens  are  near 
+  fig.  11  ;  all  the  rest,  and  there  are  over  eighty,  are  like  +  fig.  12. 
—Locality  .-  Nos.  1-11,  22,  23,  33,  34,  37,  39.  Most  of  them  were 
found  at  Nos.  1-11. 

"*"P1.  20,  fig.  13.  Nine  examples  occur,  and  one  is  in  the 
trifacial  condition. — Locality  ;  Nos.  1,  38,  42  44 :  the  trifacial 
specimen  at  No.  43. 

*P1.  20,  fig.  14.     Eight  specimens  found. — Locality;  Nos.  1-4. 


HENRY   SIDEBOTTOM   ON    LAGENAE   OF   THE    SOUTH-WEST   PACIFIC.     199 

Lagena  auriculata  Brady  var.  nov.  caudata  (PI.  18,  figs.  2,  3). 

Test  compressed,  the  lower  part  of  the  body  faintly  striated. 
A  single  long  spine,  probably  always  bent  more  or  less  to  one 
side,  projects  at  the  base.  Orifice  situated  at  the  end  of  a  long 
neck.     In  fig.  2  the  basal  spine  is  partly  broken  off. 

The  faint  striation  seems  to  indicate  an  affinity  with  L.  auricu- 
lata var.  costata  Brady,  but  in  order  to  avoid  giving  subvarietal 
names,  I  have  treated  it  as  a  variation  of  L.  auriculata. — 
Locality  :  No.  2. 

Lagena  auriculata  Brady  var.  nov.  circunicincta  (PI.  18,  fig.  4). 

Test  compressed,  subcarinate,  except  at  the  lower  edge  and 
base,  where  the  keel  is  well  developed.  A  few  costae  run  across 
each  face  of  the  test.  Orifice  oval.  Entosolenian  tube  long  and 
curved.  Four  specimens  occur.  There  are  six  tests  on  the 
square,  but  two  do  not  belong  to  the  same  variety. — Locality  .- 
No.  43,  and  one  of  the  following  stations :  Nos.  38,  42,  44,  but 
which  one  is  doubtful. 

Lagena  auriculata  Brady  var.  nov.  clypeata  (PI.  18,  fig.  5). 

Test  compressed,  carinate.  Orifice  oval.  Two  raised  oval 
rings  (sometimes  slightly  irregular)  on  each  face  of  the  shell. 
The  loops  at  the  base  small.  Entosolenian  tube  long  and  curved. 
It  is  easy  to  miss  noticing  the  loops.  The  tests  vary  a  little 
from  one  another  in  outline.  The  keel  is  not  quite  so  wide  as 
indicated  in  the  drawing. 

About  twenty  specimens  are  arranged  on  the  same  square  as  a 
number  of  L.  Orbignyana  sp.  var.  Waller iana  Wright,  for  which 
they  may  have  been  temporarily  mistaken. — Locality :  The 
majority  must  have  been  found  either  at  Nos.  42  or  43,  or  both. 

Lagena  auriculata  Brady  var.  Sidebottom  (PI.   18,  fig.   6). 

Lagena  auriculata  Brady  var.  Sidebottom,  1912,  Journ.  Q.  M.  C.r 
p.  421,  pi.  20,  figs.  15-18. 

Pi.  18,  fig.  6  and  *  pi.  20,  fig.  15.  I  have  figured  one  of 
average  size.  There  are  often  a  few  spines  at  the  base. — 
Locality  ;  Nos.  4,  23,  24,  38-44. 

A  few  elongate  examples  occur. — Locality  ;  Nos.  2.  3- 


.200    HENRY   SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST    PACIFIC 

Several  approach  +  pi.  20,  fig.  18. — Locality  :  Uncertain. 

+  PI.  20,  fiff.  17.  A  number  are  near  this  form,  and  mixed 
^vvith  them  are  several  identical  with  Mr.  Millett's  Malay  Report, 
pi.  14,  fig.  15.—  Locality :  Nos.  1-4. 

A  few  elongate  specimens  occur,  the  body  being  striated,  or 
^wrinkled,  as  indicated  in  the  figure. — Locality  :  Nos.  8,  9,  11. 

Lagena  auriculata  Brady  var.  arcuata  Sidebottom. 

Lagena  auriculata  Brady  var.  arcuata  Sidebottom,  1912,  Journ. 
Q.  M.  C,  p.  421,  pi.  20,  figs.  19,  20. 

+  PI.  20,  fig.  19.  The  specimens  differ  from  the  figure,  as  the 
arches  radiate  from  the  base. — Locality  :  Nos.  4-7,  9,  10. 

Lagena  auriculata  Brady  var.  costata  Brady. 

Lagena  auriculata  Brady  var.  costata  (Brady)  Sidebottom,   1912, 
Journ.  Q.  M.  C,  p.  422,  pi.  20,  figs.  21,  22. 

*  Pi.  20,  fig.  22.  See  remarks,  +  p.  422.— Locality :  Nos.  23, 
24,  29,  33,  39~  42. 

Lagena  auriculata  Brady  var.  duplicata  Sidebottom 

(PI.   18,  figs.  7,  8). 

Lagena  auriculata  Brady  var.  duplicata  Sidebottom,  1912,  Journ. 
Q.  M.  a,  p.  422,  pi.  20,  fig.  23. 

Pi.  18,  fig.  7.  The  loops  in  this  case  extend  from  the  base 
almost  to  the  neck.  At  the  first  glance,  I  took  the  specimens  to 
be  L.  Orbignyana,  as  in  some  of  the  specimens  debris  or  shell- 
growth  partially  covered  the  loops,  the  inner  sides  of  which  are 
quite  close  to  the  keel  ;  a  closer  examination  of  other  examples, 
which  are  free  from  debris,  show  the  loops  to  be  complete. 
The  tests,  of  which  there  are  tan,  are  large. — Locality  :  No.  42. 

Note. — The  above  might,  with  equal  propriety,  be  treated  as 
a  carinate  form  of  L.  alveolata  var.  separans  Sidebottom,  1912, 
■+pl.  21,  fig.  4. 

PL  18,  fig.  8.     This  differs  from  +  PI.  20,  fig.  23,  chiefly  in  the 


HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     201 

absence  of  the  carina.  Very  rare. — Locality  :  Nos.  29.  34,  39. 
Two  or  three  were  found  at  other  stations  besides  those  indicated. 

Note. — Several  examples  occur  almost  identical  with  the  above  ; 
the  only  difference  being  that  the  loops  merge  together  as  in 
L.  alveolata,  and  so  must  be  treated  as  such. 

*  PI.  20,  fig.  23.     One  specimen.     Locality:  Uncertain. 

Lagena  fimbriata  Brady  (PL  18,  tig.  9). 

Lag ena  fimbr lata  Brady,  Quart.  Journ.  Micr.  Sci.,  vol.  21  (N.S.), 

1881,  p.  61. 
Lagena  fimbriata  Brady.  1884,  p.  486,  pi.  60,  figs.  26-28. 

Two  specimens  occur  similar  to  the  Challenger  Report,  pi.  60, 
fig.  28. — Locality  :  Uncertain. 

Pi.  18,  fig.  9.  This  is  a  neat,  small,  compactly  built  variety, 
and  the  fimbriated  portion  does  not  appear  liable  to  get  fractured. 
The  tube  is  curled  upon  itself.  The  test  is  moderately  com- 
pressed, and  the  opening  at  the  base  is  very  narrow.  This  variety 
must  not  be  confused  wTith  pi.  20,  fig.  28. — Locality  :  Nos.  31,  43, 
44  ;  frequent  at  No.  44. 

+  PI.  20,  fig.  24.  Two  examples  only  occur. — Locality  : 
No.  31. 

+  P1.  20,  fig.  25.  Eight  specimens. — Locality  :  One  or  more  of 
the  following  stations :  Nos.  5,  6,  22. 

+  PI.  20,  fig.  26.  Four  very  fine  examples  occur. — Locality  : 
Nos.  4,  6,  8,  10. 

Three  specimens,  with  the  base  more  pointed  and  the  opening 
more  contracted,  are  also  on  the  slide. — Locality  :  Nos.  7,  10,  12. 

Lagena  fimbriata  Brady  var.  nov.  duplicata  (PI.  18,  fig.  10). 

Test  compressed,  ovate.  There  are  two  narrow  loops,  side  by 
side,  across  the  width  of  the  test  at  its  base.  Tube  curled  on 
itself.  I  think  the  walls  of  the  loops  are  tubulated,  but  cannot 
be  quite  certain  about  it.  A  solitary  specimen. — Locality: 
Uncertain. 

There  is  another  test  which  has  the  orifice  wider,  and  the  tube 
short  and  straight.  The  loops  are  in  the  same  position,  but  so 
feebly  represented  that  it  is  doubtful  whether  it  belongs  to  the 
above  variety. 

Journ.  Q.  M.  C,  Series  II. — No.  73.  14 


202    HENRY   SIDEBOTTOM   ON   LAGENAE  OF   THE   SOUTH-WEST   PACIFIC. 

Lagena  fimbriata  Brady  var.  occlusa  Sidebottom. 

Lagena  fimbriata   Brady  var.    occlusa   Sidebottom,   1912,   Journ.. 
Q.  M.  C,  p.  423,  PI.  20,  figs.  27,  28. 

+  PI.  20,  fig.  27.  Common.  Most  of  the  specimens  have  the 
opening  at  the  base  more  open  than  in  the  illustration.  See 
remarks,  +  p.  423.—  Locality:  Nos.  1-4,  6-13,  15,  17,  19,  22,  24, 
25,  29,  31,  33-35,  37-42. 

Lagena  alveolata  Brady  (PI.  18,  figs.  11,  12). 
Lagena  alveolata  Brady,  1884,  p.  487,  pi.  60,  figs.  30,  32. 

PL  18,  fig.  11.  The  tests  are  large  and  strongly  built.  All  are 
in  the  apiculate  condition.  The  dotted  line  indicates  the 
boundary  of  the  chamber,  thus  showing  the  thickness  of  the 
wall.     Orifice  oval.    Twelve  examples  occur. — Locality  :  Nos.  1,  5. 

PL  18,  fig.  12.  There  are  a  large  number  present.  The  tests 
are  fairly  well  compressed.  The  chief  peculiarity  is  that,  though 
the  entosolenian  tube  is  straight,  the  orifice  opens  out  well  below 
the  median  line.  The  part  above  the  j  orifice  is  sharpened.  The 
loops  at  the  base  are  small,  and  their  outer  edges  do  not  project 
nearly  so  far  as  does  the  central  carina. — Locality :  Nos.  1-15, 
17-20. 

"**  PL  21,  fig.  1.  Unfortunately  the  specimens  are  mixed  with 
another  species,  so  that  the  stations  at  which  they  were  found 
are  uncertain.     There  are  a  fair  number  on  the  slide. 

**"  PL  21,  fig.  2.  Good  examples  are  present. — Locality  :  Nos.  1, 
3-5,  7, 10,  16,  17. 

Lagena  alveolata  Brady  var.  carinata  Sidebottom. 

Lagena  alveolata  Brady  var.  carinata  Sidebottom,   1912,  Journ. 
Q.  M.  C,  p.  424,  pi.  21,  fig.  3. 

This  form  is  very  rare  in  this  collection. — Locality :  Nos.  24,. 
39,  40. 

Lagena  alveolata  Brady  var.  substriata  Brady. 

Lagena  alveolata  var.  substriata  Brady,  1844,  p.  488,  pi.  6,  fig.  34. 

A  single  specimen.  It  is  not  quite  typical,  the  neck  of  the 
test  being  more  produced  than  in  the  Challenger  figure. — 
Locality :  No.  39. 


HENRY    SIDEBOTTOM    ON    LAGENAE   OF  THE   SOUTH-WEST   PACIFIC.    203 

Lagena  alveolata  Brady  var.  separans  Sidebottom. 

Lagena  alveolata  Brady  var.  separans  Sidebottom,   1912,  Journ. 
Q.  M.  C,  p.  425,  pi.  21,  fig.  5. 

Locality:  Nos.  1-3,  5,  6, 17-20,  23-25,  34,  38. 

Lagena  clypeato-marginata  Rymer-Jones  var. 

Lagena  clypeato-mavginata  Rymer- Jones  var.  Sidebottom,  1912, 
Journ.  Q.  21.  C,  p.  425,  pi.  21,  fig.  6. 

Several  examples  occur. — Locality  :  Uncertain. 

Lagena  magnifica  Sidebottom. 

Lagena   magnifica   Sidebottom,    1912,   Journ.   Q.  M.   6'.,   p.    425, 
pi.  21,  fig.  8. 

A  few  of  the  specimens  are  in  the  transparent  condition. — 
Locality  :  ]S"os.  1-5,  7. 

Lagena  Elcockiana  Millett. 

Lagena  Elcockiana  Millett,  1901,  p.  621,  pi.  14,  figs.  5,  6. 
Lagena  Elcockiana  (Millett)  Sidebottom,  1912,  Journ.   Q.  M.  C, 
p.  426,  pi.  21,  fig.  9. 

A  single  specimen. — Locality  :  Uncertain. 

Lagena  galeaformis  Sidebottom. 

Lagena  galeaformis  Sidebottom,   1912,  Journ.   Q.  M.  C,  p.   426, 
pi.  21,  figs.  11,  12. 

+  P1.  21,  fig.  12.  Only  the  trifacial  form  appears  to  be  repre- 
sented in  these  gatherings. — Locality  :  Nos.  1-3. 

There  are  a  few  tests  which  may,  or  may  not,  be  the  bifacial 
form  of  this  species.  I  have  included  them  under  **"pl.  20,  fig.  17, 
on  page  421.  They  are  not  so  stout  as  this  figure  represents, 
and  the  side  keels  are  entire  as  far  as  the  tubular  process. 

Lagena  protea  Chaster. 

Lagena  protect  Chaster,  1892,  p.  62,  pi.  1,  fig.  14. 

See  remarks,  +  p.  427 .—Locality  :  Nos.  2,  10,  17,  19,  22,  23,  25, 
38,  39,  43,  44. 


204    HENRY   SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST    PACIFIC 

Lagena  invaginata  sp.  nov.  (PL  18,  fig.  13). 

Test  slightly  carinate ;  oral  end  protruding  and  arched ; 
orifice  a  narrow  slit,  perhaps  barred.  The  front  highly  convex  ; 
the  back  flat,  with  a  large  concave  recess  at  the  base.  The 
entosolenian  tube  long  and  bent  to  one  side.  Twenty-one 
examples  occur. — Locality  :  Nos.  38,  41,  42  ;  chiefly  at  No.  42. 

Lagena  reniformis  sp.  nov.  (PI.  18,  fig.  14). 

The  test  reminds  one  of  a  kidney  bean  in  shape ;  the  orifice  is 
situated  on  one  side  of  the  median  line.  The  entosolenian  tube 
is  long  and  attached.  A  few  of  the  specimens  are  not  nearly  so 
wide  in  relation  to  the  height  as  the  one  figured. — Locality : 
About  sixteen  at  No.  44.  It  occurs  also  at  several  other 
stations. 

Lagena  reniformis  sp.  nov.  var.  (PI.  18,  fig.  15). 

I  am  treating  this  as  a  variation  of  the  above.  I  believe  the 
orifice  is  composed  of  a  series  of  pores,  at  any  rate  it  is  exceed- 
ingly narrow.  There  are  two  other  tests  along  with  it,  in  which 
the  width  is  about  equal  to  the  height,  but  I  think  they  belong 
to  the  same  variety. — Locality  :  Uncertain. 

Lagena  reniformis  sp.  nov.  var.  spinigera  (PI.  18,  fig.  16). 

The  test  is  compressed,  and  the  two  spines,  one  on  either  side, 
project  upwards.  The  orifice  is  slightly  sunk,  and  the  tube  is 
long  and  attached,  reaching  almost  round  the  shell.  Two 
specimens  only  found. — Locality  :  Nos.   29,  44. 

Lagena  sp.  incerfc.  (PI.  18,  fig.  17). 

Probably  this  is  only  L.  marginata  in  a  contorted  condition. 
The  test  is  carinate,  compressed  and  twisted.  Two  occur. — 
Locality  :  Both  at  No.  15  ;  or  one  at  No.  1  and  the  other  at 
No.  15. 

Lagena  lagenoides  Williamson  sp.  var.  (PI.  18,  fig.  18). 

The  test  is  elongate,  not  much  compressed,  and  bicarinate. 
Aperture  fissurine.  The  keels,  which  only  project  slightly,  are 
tubulated. 

I  take  this  to  be  an  elongate  variety  of  L.  lagenoides,  William- 
son sp.,  pi.  17,  fig.  1.     Three  occur. — Locality  :  No.  40. 


HENRY   SIDEBOTTOM    ON   LAGENAE   OF  THE   SOUTH-WEST   PACIFIC.     205 

Lagena  staphyllearia  Sch wager  sp.  var.  (PI.  18,  fig.  19). 

Test  compressed  (lower  part  angular  in  outline)  with  five  very 
small  protuberances  arranged,  as  shown  in  the  drawing,  on  the 
edge  of  the  shell.  The  entosolenian  tube  starts  straight  and 
then  bends  towards  the  back  of  the  test.  Only  four  occur,  and 
they  vary  a  little  in  outline. — Locality  :  Nos.  3,  11. 

Lagena  sp.  incert.  (PI.  18,  fig.  21). 

I  have  only  made  an  outline  drawing  of  this  form,  because  I 
am  not  sure  what  its  natural  condition  may  be.  The  test 
is  compressed,  and  nearly  all  the  examples  are  covered  with 
shell-growth,  which  has  a  sugary  appearance.  The  colour  is 
a  light  cream.  In  those  that  are  partially  free  from  this  in- 
crustation, the  test  appears  to  be  more  or  less  in  a  hispid 
condition.  The  carina,  starting  at  the  orifice,  often  ends  abruptly, 
as  showrn  in  the  illustration,  but  sometimes  it  gradually  diminishes 
until  it  is  lost  about  half-way  down  the  test.  Two  or  more 
spines  adorn  the  base.  It  may  be  a  compressed  form  of  L.  hispida. 
—Locality :  Nos.  23,  29,  39,  40,  41. 

Lagena  sp.  incert,  (PI.  18,  fig.  22). 

I  am  puzzled  with  this  form,  not  knowing  whether  to  treat  it 
as  L.  marginata  in  which  the  keel  has  split,  thus  forming  two 
long  loops,  one  on  either  side  of  the  test ;  or,  as  L.  auriculata  in 
which  the  loops  extend  almost  to  the  neck.  It  will  be  noticed 
that  the  loops  are  quite  separate  at  the  base.  Three  occur.  The 
specimens  are  mixed  with  those  of  another  form. — Locality :  One, 
must  have  been  found  at  No.  43  or  No.  44. 

?  Lagena  sp.  (PL  18,  figs.  23,  24). 

I  believe  this  to  be  a  foraminifer,  but  it  is  very  doubtful  if  it 
be  a  Lagena.  There  was  a  small  test,  on  the  same  square,  which 
had  every  appearance  of  being  the  initial  chamber  of  the  same 
species.  Unfortunately,  in  using  a  high-power  lens  for  examina- 
tion, I  accidentally  crushed  the  specimen  ;  but  I  bad  previously 
made  an  outline  drawing  of  it,  see  pi.  18,  fig.  24. 

The  large  test,  pi.  18,  fig.  23,  is  not  compressed.  The  orifice  is 
a  rosette  in  form,  and  the  upper  part  of  the  test  is  covered  with 
a   raised   irregular   mesh.     Rows   of  tubular  projections  run  at 


206    HENRY   SIDEBOTTOM   ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC. 

intervals  across  the  test.  It  being  a  solitary  example  I  do  not 
care  to  make  a  section  of  it,  but  probably  it  would  reveal  a  series 
of  chambers.  As  Mr.  Thornhill  has  placed  it  among  the  Lagena, 
and  it  is  such  an  interesting  object,  I  cannot  resist  the  oppor- 
tunity of  figuring  it.  It  is  opaque,  but  the  single-chambered 
specimen  was  quite  transparent. — Locality  :  No.  42. 

Lagena  maculata  sp.  nov.  (PI.  18,  fig.  25). 

I  was  unable,  for  various  reasons,  to  make  out  the  nature  of 
this  interesting  species,  so  submitted  the  test  to  Mr.  Earland,  and 
he  has  kindly  sent  me  the  following  description  of  it : 

"The  shell  appears  to  consist  of  two,  probably  three  layers. 
An  inner  test  which  is  covered  with  a  raised  hexagonal  outline 
pattern,  like  network  over  a  ball,  and  this  in  turn  is  covered 
with  an  extremely  thin  outer  test.  This  latter  may  be  merely 
chitinous  or  membranous ;  it  is  sufficiently  thin  to  show  diffrac- 
tion spectra.  "Where  this  outer  layer  is  stretched  over  the  raised 
pattern  it  is  depressed  in  a  rounded  fashion,  as  though  it  had 
been  pressed  down  with  the  tip  of  the  finger  into  the  hexagonal 
cavity  beneath." 

A  solitary  example.  It  belongs  to  the  Waterwitch  set  of 
Lagenae.     Test  not  compressed. 

Locality  :  No.  13.  Station  238,  Lat,  12"44'  S.,  Long.  179*09'  W. 
(1,050  fms.). 

Lagena  marginata  Walker  and  Boys  var.  ventricosa  Silvestri. 

Lagena  ventricosa  Silvestri,  1903-1904,  Accad.  Reale  delle  Scienze 
di  Torino,  p.  10,  figs.  6  a-e. 

This  seems  to  me  simply  a  stout  form  of  L.  marginata.  There 
are  eleven  large  specimens,  but  the  carina  is  carried  a  little 
farther  up  the  test.  Three  of  the  tests  are  nearly  round  in 
section.  Examples  moderately  compressed,  with  orifice  of  the 
same  character,  I  have  placed  with  L.  marginata. — Locality : 
Nos.  5,  15. 

[Mr.  Henry  Sidebottom  has  decided  to  make  a  type -slide  of  the 
species  described  in  his  two  papers  as  an  index  to  the  collection 
of  Lagenae.  The  collection  will  then  be  presented  to  the  British 
Museum  (Natural; History),  South  Kensington,  under  the  title, 
<l  The  Thornhill  Collection  of  Lagenae  (South-West  Pacific)." 


HENRY   SIDEBOTTOM   ON    LAGENAE  OF   THE   SOUTH-WEST   PACIFIC.     207 


DESCRIPTION   OF   PLATES. 


Figs. 


1-3. 

L. 

4. 

L. 

5,6. 

L. 

7,8. 

L. 

9,10. 

L. 

11. 

L. 

12,  13. 

L. 

1-1. 

L. 

15. 

L. 

16. 

L. 

17. 

L. 

18,  19. 

L. 

20. 

L. 

21. 

L. 

22. 

L. 

23. 

L. 

24,  25. 

L. 

26. 

L. 

27. 

L. 

28. 

L. 

29. 

L. 

30. 

L. 

31. 

L. 

32. 

L. 

Q  D 

-DO. 

L. 

Plate   15. 

glohosa  Montagu  sp.,  x  50 

apiculata  Reuss  sp.,   x  25 

longispina  Brady,  x  50 

botelliformis  Brady,  x  50 

laevis  Montagu  sp.,  x  50 

aspera  Beuss,  x  50 

aspera  Reuss,  x  75 

rudis  Reuss,  x  50 

hispida  Reuss,  x  50     . 

hispida  Reuss  var.  tuhulata  Sidebottom,  x  50 

striata  d'Orbigny  sp.,  x  75  . 

costata  Williamson  sp.,   x  75 

acuticosta  Reuss,  x  50 

hexagona  Williamson  sp.,  x  50 

hexagona  Williamson  sp.,  x  115 

hexagona    Williamson,    sp.,    compress 

X  115 

sulcata  Walker  and  Jacob  sp.,  x  50 

ph<migera  Brady,  x  50 

semilineata  Wright,  x  50    . 

crenata  Parker  and  Jones,  var.  x  50 

Thomhitti  Sidebottom,  x  75 

stettigera  Brady  var.  eccentrica  Sidebottom,  x  50 

stelligera  Brady  var.  eccentrica  Sidebottom,  com 

pressed  variety,  x  50     . 
foveolata  Reuss (?),  var.  paradoxa  Sidebottom,  x  75 
Hertv:igiana  Brady,  X  50  . 


ed    varietv 


Page 

164 

165 

165 

166 

166 

167 

167 

168 

168 

168 

169 

170 

171 

171 

171 

171 
172 
173 
173 
174 
174 
175 

175 

177 
178 


208    HENRY    SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST  PACIFIC. 


Plate  16. 

Figs. 

1.  L.  splenclida  sp.  nov.,  x  75 

2,  3.     Diagrams  of  decoration  ...... 

4.  L.  spumosa  Millett,  x  75         .         .         . 

5.  L.  laevigata  Reuss  sp.,  x  115 

6.  L.  laevigata  Keuss  sp.  var.  virgulata  Sidebottom,  x  50 

7.  L.  acuta  Reuss  sp.  x  25  .         .  . 

8.  L.  acuta  Keuss  sp.  var.,  X  50  . 

9.  L.  lucida  Williamson  sp.,  X  50 
10-13.   L.  fasciata  Egger  sp.,  X  50 

14.  L.  fasciata  Egger  sp.  var.  carinata  Sidebottom,  X  25 

15,  16.   L.  fasciata  Egger  sp.  var.  carinata  Sidebottom,  x  50 

17.  L.  marginata  Walker  and  Boys,  x  50 

18.  L.    marginata    Walker    and   Boys,  x  75, 

form      .  .  . 

19.  20.  L.  marginata  WTalker  and  Boys,  x  75 

21.  L.  compresso-marginata  Fornasini,  x  75 

22.  L.  marginata    Walker    and    Boys,    var. 

Chapman,  x  25     . 

23.  24.  L.  marginato -perforata  Seguenza,  x  50 
25.  L.  marginato-perforata  Seguenza,  x  75 
26-28.   L.  lagenoides  Williamson  sp.,  x  50  . 
29.         L.  lagenoides  Williamson  sp.,  x  75  . 


Trifacial 


catenulosa 


Page 

178 

178 

179 

181 

181 

182 

182' 

183 

183 

184 

184 

186- 

186. 
186 
187 

187 
189 
189 
190 
190 


HENRY   SIDEBOTTOM    ON    LAGENAE   OF   THE   SOUTH-WEST   PACIFIC.     209' 


Plate  17. 

Figs. 

1.  L.  lagenoides  Williamson  sp.,  x  75  . 

2.  L.  lagenoides  Williamson  sp.  var.  nov.  duplicate/,,  X  75 

3.  L.formosa  Schwager,  x  50 
4-7.  L.formosa  Schwager,  x  75 

8.  L.  formosa  Schwager  var.,  x  75 

9.  L.  Orbignyana  Seguenza  sp.,  x  75 

10.  L.  Orbignyana  Seguenza  sp.,  x  50 

11.  L.  Orbignyana  Seguenza  sp.,  X  75 

12.  L.  Orbignyana  Seguenza  sp.  var.  lacunata  Burrows 

and  Holland,  x  50 

1 3.  L.  Orbignyana  Seguenza  sp.  var.  pulcheUa  Brady,  X  75 

14.  L.  Orbignyana  Seguenza  sp.var.  clathrata, Brady,  x  75 

15.  L.  Orbignyana  Seguenza  sp.  var.,  x  75 

16.  17.  L.  bicarinata  Terquem  sp.,  x  50 

18.  L.  bicarinata  Terquem  sp.,  x  75 

19.  L.  bicarinata  Terquem  sp.,  x  75 

20.  L.  bicarinata  Terquem  sp.,  x  75 

21.  L.  auricidata  Brady,  x  50 

22.  L.  auricalata  Bradv,  x  75 


Page 

190 

191 

191 

191 

192 

194 

194 

194 

194 

195 

196 

196- 

197 

197 

197 

197 

198 

19& 


'210     HENRY   SIDEBOTTOM    ON    LAGENAE    OF  THE    SOUTH-WEST    PACIFIC. 


Plate  18. 

Figs. 

1.  L.  auriculata  Brady,  x  75 

2,  3.  L.  auriculata  Brady  var.  nov.  caudata,  x  25    . 

4.  L.  auriculata  Brady  var.  nov.  circumcincta,  X  115 

5.  L.  auriculata  Brady  var.  nov.  clvpeata,  x  115. 

6.  L.  auriculata  Brady  var.,   x  75 

7.  L.  auriculata  Brady  var.  duplicata  Sidebottom,  x  25 

8.  L.  auriculata  Brady  var.  duplicata  Sidebottom,  x  50 

9.  L.  fimbriata  Brady,  x  75 

10.  L.  fimbriata  Brady  var.  nov.  duplicata,  x  75 

11.  L.  alveolata  Brady,  x  50. 

12.  L.  alveolata  Brady,  x  75 

13.  L.  invaginata  sp.  nov.,  x  115  . 

14.  L.  reniformis  sp.  nov.,  X  75 

15.  L.  reniformis  sp.  nov.  var.,  x  75 

16.  L.  reniformis  sp.  nov.  var.  spinigera,  X  7 

17.  Lagena  sp.  incert.,  x  75  . 

18.  L.  lagenoides  Williamson  sp.  var.,  x  50 

19.  L.  staphyllearia  Sch wager  sp.  var.,  x  75 

20.  L.  squamoso-alata  Brady,  x  75 

21.  Lagena  sp.  incert.,  x  75  . 

22.  Lagena  sp.  incert.,  x  50  . 

23.  24.  (?)  Lagena  sp.,  x  50 
2?.  L.  maculata  sp.  nov.,  x  75 


Page 

198 
199 
199 
199 
199 
200 
200 
201 
201 
202 
202 
204 
204 
204 
204 
204 
204 
205 
193 
205 
205 
205 
206 


Journ.  Quekett  Microscopical  Club,  Scr.  2,  Vol.  XII.,  No.  73,  Noc  mber  1913. 


Journ.Q.M.C. 


Ser.  2, Vol. XII. PI.  IS. 


H.Sidebottoni  del.ad  nat. 


West, Newman  lith. 


Laqenae  of  the   South  West  Pacific    Ocean. 


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Jour n.  O.M.C. 


Sep.  2, Vol.  XII. PL  16. 


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We  s  t  .Newman 


Lagenae   of  the   South  West  Pacific    Ocean. 


Joum.  Q.M.C. 


Ser.  2, Vol.  XII,  PI.  17. 


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Lagenae   of  the   South  West  Pacific    Ocesun. 


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Lagenae   of  the    South  West  Pacific    Ocean. 


211 


GASTROTRICHA. 

By  James  Murray,  F.R.S.E. 

Communicated  by  D.  J.  Scourjield. 
{Bead  October  28th,  1913.) 

Plate  19. 

INTRODUCTION. 

I  have  been  reluctant  to  attempt  an  introduction  to  the  study 
of  the  Gastrotricha,  since  my  knowledge  of  the  group  is  by  no 
means  profound,  and  such  as  it  is  has  been  only  recently  acquired. 
Jt  is  a  group  which  has  now  reached  such  dimensions  that  it  is 
desirable  there  should  be  in  the  English  language  some  sort  of 
synopsis  of  our  present  knowledge,  and  as  there  appears  to  be  no 
one  else  in  the  field  to  supply  this  want,  I  shall  here  do  the  best 
I  can. 

The  main  part  of  this  paper  is  an  annotated  bibliography, 
which  I  hope  will  save  students  much  of  the  trouble  I  have  had. 
It  is  difficult  to  hit  a  just  mean  between  giving  too  much  and  tco 
little.  If  too  comprehensive  and  not  annotated,  a  bibliography 
rather  hinders  than  helps  by  making  the  mass  of  works  to  be 
consulted  seem  too  great.  A  work  is  judged  by  its  title  to  be  one 
that  must  be  consulted,  and  after  much  labour  is  found  to  be  of 
no  importance.  I  had  a  long  search  for  a  new  genus  and  species, 
Gastrochaeta  ciliata,  described  by  Grimm,  before  I  found  that  the 
name  occurred  in  a  mere  list,  in  Russian,  without  a  figure, 
and  that  in  a  footnote  all  the  comparison  made  was  with  species 
of  Desmoscolex,  which  belongs  to  a  quite  different  group  of 
worms  (25). 

If  the  bibliography  is  too  condensed  the  student  is  always 
liable  to  suspect  that  a  work  omitted  from  it  has  not  come  to  the 
knowledge  of  the  compiler.  Such  things  frequently  happen.  ■  I 
have    here    tried    to    keep    a   proper   balance.       All    important 


212  J.    MURRAY    ON    GASTROTRICHA. 

general,  biological  and  systematic  works  known  to  me  are 
included,  as  well  as  any  really  important  faunistic  studies. 
Every  work  is  given  in  which  new  species,  or  supposed  new 
species,  or  groups  of  higher  value  are  described.  The  systematic 
student  wants  these  principally.  There  are  omitted  all  merely 
popular  accounts,  all  trifling  faunistic  studies  (records  usually  of 
doubtful  value),  all  references  in  textbooks  of  zoology  which 
contain  nothing  fresh,  pronouncements  on  systematic  position, 
which  are  mostly  only  opinions  not  backed  by  personal  knowledge 
of  the  animals. 

Monographists  and  close  students  of  distribution  will  require 
more  than  this  bibliography  contains,  but  they  will  be  able  to 
get  it  for  themselves. 

It   is  unfortunate  that  the  Gastrotricha,  which   include  those 
old   familiar   friends  of    the   students  of    pond   life — Chaetonotas 
larus  and  Ichthydium  podura — have   no  popular   name.     Gosse's 
proposed   name    of    "  hairy-backed   animalcules  "  is  entirely  un- 
suitable,    since    some    of      the    genera    are    not    hairy-backed 
[Ichthydium,  Lepidoderma).     I  confess   I    am   unable  to  suggest 
any  appropriate   name.     The   name   suggested   by   the  scientific 
term    for   the    whole    group,    which    embodies    almost    the    only 
character  which  they  all  possess,  is  unsuitable  for  popular  use_ 
The  Gastrotricha    are   not   animals  which  can   be   named  off- 
hand.       The     days    when     we    found     Chaetonotus     larus    and 
Ichthydium  podura,  occasionally  varied  by  C.  maximus,  on  all  our 
pond- life  excursions  are  over.      There  are  a  host  of  Chaetonoti 
which  have  contributed  to  the  records  of  0.  larus.     These  species- 
are  all  alike  to  a  casual  glance,  but  are  distinguished  by  minute 
characters — the   possession  of  small   branches   by  certain  of  the 
bristles,  the  form  of   the  minute  scales  which  bear  the  bristlesr 
etc.      Some  of  these   are  so  delicate  that  a  high  power  and  an 
oil-immersion    lens    would    be    needed    for    their    certain    deter- 
mination.    This  is   impossible    to    apply   to    a  living  and    lively 
Chaetonotus,   and  as  to  killing  the  creature  merely  in    order  to 
find  out  its  name,  well — a  philosophic    naturalist  might    prefer- 
to  remain    ignorant.     To    destroy    this    marvellous    little  living 
gem  simply  to  know  how  to  label  it  ;  is  it  worth  while  1 

Now  we  students  of  microscopic  life  cannot  pretend  to  be 
squeamish ;  we  have  learned  to  kill  lightly  ;  every  time  we  clean, 
a    cover-glass    we    annihilate    a    world.     But  when  it   comes    to» 


J.    MURRAY    ON    GASTROTRICHA.  213 

deliberately  ending  the  individual  life  which  we  have  before  our 
eves,  intelligent,  and  surely  innocent,  I  confess  that,  old  and 
hardened  as  I  am  at  the  game,  I  feel  guilty  of — murder. 
My  ideal  is  that  realised  by  Mr.  Bryce,  with  his  "  zoo "  of 
Rotifera,  all  kept  alive  in  cells,  visited  again  and  again  for  weeks 
and  months,  till  they  become  old  familiar  friends,  each  known  by 
sight  and  name  :  where  a  death  in  the  family  is  regretted,  and 
the  beasties,  in  fact,  reach  a  ripeness  of  old  age  which  must  be 
rare  under  natural  conditions. 

I  wish  to  thank  Mr.  Rousselet  and  Mr.  Bryce  for  the  assistance 
they  have  given  me  in  preparing  this  paper,  by  lending  me 
specimens  and  books,  and  Mr.  Harring  for  bibliographical  refer- 
ences and  extracts  from  works  which  I  had  not  seen. 

Form  axd  Structure. 

AH  Gastrotricha  are  built  on  a  very  uniform  plan.  Most  of 
them  have  a  roundish,  often  3-  or  5-lobed  head,  a  more  or  less 
distinct  neck  and  a  slightly  expanded  body,  diminishing  pos- 
teriorly to  a  usually  forked,  but  sometimes  undivided  extremity 
{tail  or  foot).  The  principal  external  features  are  :  the  tubular 
mouth,  certain  sensory  hairs  on  the  head,  various  forms  of  scales 
and  hairs  clothing  the  dorsal  surface.  The  ventral  surface  is 
traversed  for  its  whole  length  by  two  bands  of  vibratile  cilia,  by 
which  the  creatures  can  creep  in  the  manner  of  an  Adineta,  and 
sometimes  even,  apparently,  swim.  A  few  possess  clear  bodies 
which  have  been  supposed  to  be  eyes. 

Of  the  internal  structure  I  shall  say  little,  as  I  have  given  it 
little  study,  and  I  can  only  quote  from  authors  who  have  studied 
it.  The  animals  are  on  about  the  same  plane  as  the  Rotifera  for 
•complexit}',  but  they  look  much  simpler — fewer  organs  are  readily 
visible.  A  casual  examination  shows  only  a  thick  skin  and  the 
body  cavity,  through  which  passes  the  simple  alimentary  canal  ; 
the  slender  oesophagus  passing  through  an  oblong  muscular 
pharynx ;  the  expanded  stomach  (or  intestine)  occupying  most 
of  the  body  cavity.  There  is  a  small  intestine,  from  which  the 
anus  opens  at  the  base  of  the  furea,  on  the  dorsal  side. 

Several  naturalists  have  detected  a  water-vascular  system 
somewhat  like  that  of  the  Rotifera,  but  according  to  Zelinka 
it  differs  in    many  points.     The    canals    are    much    convoluted, 


214  J.    MURRAY    ON    GASTROTRICHA. 

and  possess  only  one  vibrating  cell  corresponding  to  the  series- 
of  flame-cells  of  Rotifera ;  there  is  no  contractile  vesicle,  and  the 
canals  open  independently  on  the  ventral  side  and  have  no 
connection  with  the  intestine. 

While  the  eggs  are  frequently  conspicuous,  and  their  develop- 
ment may  be  conveniently  studied,  the  sexual  system  is  little 
known.  Zelinka  distinguishes  paired  ovaries.  If  the  supposed 
male  organs  are  such  the  Gastrotricha  are  hermaphrodite. 

Zelinka  recognises  in  the  alimentary  canal  the  following  parts  : 
mouth,  oesophagus,  stomach,  intestine  with  rectum  and  anus. 

There  is  a  well-developed  muscular  system,  and  the  brain  and 
nervous  system  are  similar  to  those  of  the  Rotifera. 

Haunts  and  Habits. 

The  Gastrotricha  are  found  mainly  in  ponds,  oftenest  among 
the  bottom  sediment  or  vegetation.  They  rarely  occur  on  mosses, 
except  the  permanently  moist  aquatic  kinds.  A  few  (at  least 
one  species,  C.  marinus)  live  in  the  sea. 

They  are  much  less  common,  even  in  ponds,  than  the 
Rotifers  and  Water-bears.  You  cannot  go  out  to  collect 
assured  of  getting  some — you  must  trust  to  casual  occurrences 
when  studying  other  things. 

There  are  no  special  methods  of  collecting  them.  They  will 
occur  among  your  Rotifers,  but  not  if  you  collect  in  clear,  open 
water.  Perhaps  the  likeliest  means  to  obtain  some  is  to  wash 
aquatic  weeds — Myriophyllum,  Fontinalis,  Lemna,  etc. 

If  you  wish  to  preserve  them  it  can  easily  be  done.  As  they 
are  not  contractile,  they  can  be  killed  without  previously 
narcotising  by  osmic  acid,  when  they  retain  the  natural  shape.. 
They  can  be  mounted  in  fluid  cells  by  Rousselet's  method,  but 
formalin  of  the  strength  used  for  Rotifers  is  not  a  suitable 
medium,  as  it  produces  subsequent  distortion.  Some  better 
medium  has  yet  to  be  found. 

They  appear  to  have  only  one  habit,  that  of  eating.  They 
ar;  always  in  motion,  some  slowly,  some  quickly,  and  always 
seem  to  be  nosing  for  food.  Yet  they  are  not  greedy  eaters,  but 
pick  daintily  here  and  there.  As  they  creep  along  over  the  weeds 
they  give  the  impression  of  active  intelligence  proportioned  to- 
their  needs. 


j.  murray  on  gastrotricha.  21£> 

Historical  Sketch. 

As  a  history  would  be  little  more  than  the  bibliography 
arranged  chronologically,  it  need  not  take  up  much  space. 

So  far  as  my  knowledge  goes,  the  first  notice  of  an  animal  of 
this  order  is  by  Joblot  (32)  1718,  who  figures  (Plate  10,  fig.  22) 
his  "  poisson  a  la  tete  en  trefie,"  which  is  the  animal  now  known 
as  Ichthydium. 

Corti  1774  (10)  speaks  of  an  "  animaluzzo  molle,"  and  figures 
it,  which  Ehrenberg  thinks  may  be  a  Chaetonotus. 

Eichhorn  1781  (20)  figures  (Plate  2,  fig.  R)  what  may  have 
been  a  Chaetonotus. 

These  were  the  pioneers,  who  bestowed  no  binomial  desig- 
nations, but,  before  either  Eichhorn  or  Corti,  Miiller  had  in  1773 
(42)  given  three  such  names,  the  first,  Cercaria  podura,  still 
persisting  as  Ichthydium  podura. 

Many  of  the  pre-Ehrenbergians  bestowed  various  names  on 
Gastrotrichs,  usually  only  in  attempts  to  classify,  not  describing 
supposed  new  species  :  Schrank  1776  (53)  Brachionvs  pilosus  ; 
Lamarck  1815  (34)  Furcocerca ;  Bory  1824  (3)  Leucophra,  1826 
(4)  Diceratella  ;  Ehrenberg's  first  attempt,  Hemprich  and  Ehren- 
berg 1828  (29)  was  Diurella  podura  (=  Ichthydium). 

Ehrenberg  did  not  notably  advance  the  knowledge  of  this 
order,  but  he  described  two  new  species  besides  others,  which  are 
not  now  recognised  as  Gastrotrichs. 

After  Ehrenberg  came  a  rather  barren  period  leading  on  to 
quite  modern  times:  Dujardin   1841  (16),   Gosse  1851  (23)  and 

1864  (24),  Schultze  1853  (55),  Schmarda  1861  (52),  Metchnikoff 

1865  (41),  Tatem  1867  (61).     The  only  works  of  any  importance 
in  this  period  are  Gosse's  and  Metchnikoff's. 

Modern  times  may  be  said  to  begin  with  Daday  in  1882  (11), 
and  the  principal  workers  have  been  Daday  1897  (12),  1905  (14), 
1910  (15);  Collin  1897  (8),  1912  (9);  Stokes  1887  (57)  (59); 
Zelinka  1889  (71);  Voigt  1904  (68);  Lauterborn  1893  (35); 
Griinspan  1908  (26);  Marcolengo  (40)  (72). 

Classification. 

The  classification  of  the  Gastrotricha  is  in  an  unsatisfactory 
condition.  They  are  difficult  animals  to  classify.  I  sympathise- 
with  the  efforts  authors  have  made  to  introduce  order  into  the- 


216  J.    MURRAY    ON    GASTROTRICHA. 

group,  and  will  not  attempt  to  modify  the  generic  arrangement, 
beyond  shifting  about  some  of  the  species.  I  am  not  qualified  to 
deal  with  the  question,  but  as  some  little  assistance  to  students 
1  shall  point  out  some  apparent  shortcomings  of  the  prevailing 
classification. 

The  three  fork-tailed  genera,  Ichthydium,  Chaetonotus  and 
Lepidoderma,  are  separated  on  very  slight  characters,  as  Stokes 
(57)  recognised  in  "  lumping "  them  all  together.  Ichthydium 
has  neither  plates  nor  dorsal  bristles  ;  Lepidoderma  has  scales, 
but  is  supposed  to  have  no  bristles ;  Chaetonotus  has  bristles, 
and  may  have  scales.  So  if  an  Ichthydium  or  a  Lepidoderma 
possesses  any  dorsal  bristles  it  becomes  a  Chaetonotus.  How 
many  bristles  are  necessary  ?  Some  so-called  Lepidoderma  have 
a  very  few  bristles.  L.  loricatus,  Stokes,  has  no  bristles,  while 
a  variety  has  four  near  the  tail. 

Authors  have  made  the  matter  worse  by  entirely  disregarding 
the  generic  definitions,  even  those  made  by  themselves.  Thus 
Zelinka's  Lepidoderma  was  instituted  first  to  contain  Dujardin's 
C.  squammatus,  which  was  described  in  these  terms,  "  Revetu 
en  dessus  de  poils  courts,  elargis  en  maniere  d'ecailles  pointues 
regulierement  imbriquees,"  and  which  is  thus  a  true  Chaetonotus, 
following  Zelinka's  own  definition. 

The  possession  or  not  of  scaly  armour  is  surely  itself  more 
important  than  the  presence  or  not  of  bristles  on  the  scales, 
but  the  character  has  not  been  used  in  classification  quite 
rightly,  for  the  scales  are  after  all  only  the  enlarged  bases  of 
the  hairs,  and  there  is  every  gradation  from  a  slightly  enlarged 
insertion  to  large  imbricated  scales. 

Authors  have  further  confused  matters  by  professing  to  identify 
a,s  the  species  of  the  earlier  authors  animals  which  are  quite 
different  from  their  descriptions  and  figures.  This  is  pernicious, 
as  the  practice  nullifies  the  meaning  of  language,  however 
precisely  used.  It  may  be  admitted  that  the  descriptions  of 
Muller  and  Ehrenberg  are  insufficient  to  distinguish  their  species 
from  the  numerous  similar  species  now  recognised.  But  the 
species  must  either  be  dropped  as  "  insufficiently  described,"  or, 
if  we  profess  to  recognise  them,  it  must  be  in  animals  possessing 
at  least  the  characters  ascribed  to  them  by  their  discoverers. 

Ehrenberg  has  many  faults,  among  which  I  reckon  not 
least    the    insufficiency    of    his    descriptions.      Frequently    these 


J.    MURRAY    ON    GASTROTRICHA.  217 

contain  no  single  distinctive  character,  and  if  it  were  not  for 
his  figures  their  recognition  would  be  impossible.  But  he  was 
not  a  slipshod  observer,  and  when  he  happens  to  mention  a 
distinctive  feature  I  have  no  doubt  the  animal  observed  possessed 
it.  Thus  when  he  distinguishes  C.  maximus  from  C.  larus  by 
its  dorsal  bristles  of  equal  length,  we  must  give  him  the  credit 
of  supposing  that  his  animal  looked  like  that,  unless  naturalists 
agree  that  no  such  animal  exists — a  difficult  thing  to  prove. 
There  are  species  with  the  dorsal  bristles  approximately  of  equal 
length,  and  so  Gosse  is  not  justified  in  identifying  as  C.  maximus 
a  species  having  the  posterior  bristles  much  longer. 

In  the  separation  into  larger  groups,  sub-orders,  or  families, 
the  group  has  been  equally  unfortunate.  The  classification  by 
Fraulein  Griinspan  (26)  recognises  three  sub-orders  : 

Suborder  I.  Euwhthtdina,  having  a  forked  tail. 

II.  Pseudopodisa,  having  an  apparently  forked  tail. 
III.  Apodixa,  without  a  forked  tail. 


55 
55 


I  am  unable  to  grasp  the  distinction  between  a  forked  tail  and 
an  apparently  forked  tail,  and  the  Apodina  include  one  genus 
(Stylochaeta)  which  has  a  forked  tail ;  minute  certainly,  but  is  a 
small  tail  not  a  tail  ? 

Zelinka's  (71)  classification  is  consistent,  but  the  more  puzzling 
genera  were  not  discovered  when  he  wrote.  He  recognises  two 
sub-orders,  and,  I  should  suppose,  three  families,  though  he  only 
names  two  : 

I.   Sub-order  :  Euichthydina,  having  a  "furca." 

1.  Family  Ichthydidae,  without  bristles. 
Genera  Ichthydiu'ni  and  Lepidoderma. 

2.  Family  Chaetonotidae,  with  bristles. 
Genera  Chaetonotus  and  Chaetura, 

II.   Sub-order:  Apodina,  without  a  "furca." 
Genera  Dasydytes  and  Gossea. 

Collin  (9)  follows  Zelinka's  classification,  naming  the  family 
Dasydytidae,  which  includes  all  the  Apodina,  and  allocating 
all  the  genera  described  since  Zelinka's  work  to  places  in  the 
three  families. 

All  this  is  very  unsatisfactory.  The  anomalies  of  these  systems 
I  have  pointed  out  as  exemplified  in  that  of  Fraulein  Griinspan. 

Journ.  Q.  M.  C.,  Series  II.— No.  73.  15 


218  J.    MURRAY    ON    GASTROTRICHA. 

I  have  no  better  to  offer,  so  I  suggest  that  we  leave  classification 
on  broad  lines  till  we  know  more,  and  classify  in  genera  only. 

These  have  also  been  badly  handled.  Ehrenberg's  two  genera, 
Ichthydium  and  Chaetonotus,  will  serve  as  a  beginning  of  classi- 
fication till  we  find  something  better.  The  distinction  between 
hairy  and  smooth  is  not  important,  and  in  many  genera  of 
animals  both  types  occur — -e.g.  Macrobiotus  among  Tardigrada, 
but  among  Gastrotricha,  if  we  are  to  have  divisions  at  all, 
we  must  be  satisfied  with  very  trivial  characters.  Miiller's 
Cercaria  poduva,  which  became  the  type  of  Ichthydium,  was 
probably  a  composite  diagnosis,  as  some  of  his  figures  show 
bristles.  I  have  shown  the  unsatisfactory  treatment  of  his  genus 
Lepidoderma  by  Zelinka,  but,  if  his  generic  characters  were 
regarded  in  allotting  species  to  it,  it  might  serve  as  a  temporary 
artificial  genus  till  we  see  our  way  out  of  the  muddle. 

Ehrenberg's  obsession  for  symmetry  in  classification  led  to 
many  obviously  false  associations  of  species,  and  tyrannised  over 
naturalists  till  a  late  period,  even  as  late  as  1864  affecting 
Gosse.  It  is  curious  now  to  regard  the  genera  once  included 
in  the  Gastrotricha — Ptygura,  Glenojihora — and  to  think  that 
Sacculus  and  Taphrocampa  were  originally  described  by  Gosse 
as  Gastrotrichs. 

Key  to  the  Genera. 

A.  Without  a  furca. 

1.  Body  with  long  bristles       ....  Dasydytes. 

2.  Body  without  long  bristles  .  Anacanthoderma. 

3.  Head  with  antennae  .       Gossea  (G.  antennigera). 

B.  Furca  minute  or  obscure. 

4.  Furca  minute,  large  barbed  bristles     .        Stylochaeta. 

5.  Furca  obscure,  short    .....     Setopus. 

6.  Head  with  antennae    .  .         .  Gossea  (two  species). 

C.  Furca  conspicuous,  body  with  bristles. 

7.  Furca  simple,  bristles  pointed      .         .        Chaetonotus. 

8.  Furca  simple,  bristles  expanded  at  apex  Aspidiophorus. 

9.  Furca  twice  furcate    .....    Chaetura. 

D.  Furca  conspicuous,  body  without  bristles. 

10.  Body  with  scaly  armour      .  .  .      Lepidoderma. 

11.  Body  without  scales    ....         Ichthydium. 


J.    MURRAY    ON    GASTROTRICHA.  219 

Note. — Anacanthoderma  can  hardly  be  separated  from  Dasy- 
dytes,  as  the  only  species  is  described  as  having  some  bristles. 
Aspidiophorus  is  a  Chaetonotus,  having  the  bristles  enlarged  at  the 
apex,  scarcely  a  generic  distinction,  as  those  having  enlarged 
bases  are  not  considered  generically  distinct.  Gossea  is  usually 
put  in  the  Apodina,  but  Daday's  two  species  possess  the  furca, 
and  Gosse's  antenniger  with  its  caudal  bundles  of  setae  may  be 
said  to  possess  the  homologue  of  the  furca.  Setopus  primus 
is  scarcely  distinguishable,  even  as  a  species,  from  Dasydytes 
bisetosus  Thomp.,  yet  from  the  possession  of  a  slight  medial 
depression  at  the  posterior  end  it  has  technically  a  furca,  and 
becomes  a  distinct  genus. 

List  of  all  Species  which  have  been  Described. 

In  alphabetical  order,  and  under  the  original  generic  names, 
with  critical  notes  on  synonymy  and  specific  values. 

1910.   Anacanthoderma  punctatum  Marcolongo  (40). 

1902.  A sp)idonotus  paradoxus  Yoigt.  (65).     Now  a  genus  Aspidio- 

phorus. 
1865.  Cephalidium  longisetosum  Met.  (41).     Is  a  Dasydytes. 
1773.  Cercaria  podura  Mull.  (42).     Now  the  type  of  Ichthydium 

Ehr. 
1887.   Chaetonotus  acanthodes  Stokes  (57). 
1887.  C.  acanthophorus  Stokes  (57). 

1903.  C.  arquatus  Voigt.  (67). 
1832.  C.  breve  Ehr.  (16). 
1889.  C.  brevispinosus  Zel.  (71). 
1901.  C.  chuni  Voigt.  (64). 

1887.  C.  concinnus  Stokes  (57).     Is  a  Lejndoderma. 

1910.  C.  decemsetosus  Marco.  (40). 

1905.  C.  dubius  Dad.  (14). 

1887.  C.  enormis  Stokes  (57). 

1905.   C.  erinaceus  Dad.  (14). 

1887.  C.formosus  Stokes  (59). 

18(54.  C.  gracilis  Gosse  (24). 

1905.  C.  heterochaetus  Dad.  (14). 

1910.  C.  hirsutus  Marco.  (40). 

1865.  C.  hystrix  Met.  (41). 


220  J.    MURRAY    ON    GASTROTRICHA. 

1910.   G.  larvides  Marco.  (40). 

1902.   C.  linguaeformis  Voigt.  (66). 

1867.  G.  longicaudatus  Tatem  (61).     Is  an  Ichthydium. 

1887.   G.  longisjnnosus  Stokes  (57). 

1887.   G.  loricatus  Stokes  (57).     Is  a  Lepidoderma. 

1893.  G.    macracanthus    Laut.     (35).       Is    probably    G.    entzii 

(Dad.). 
1889.  C.  macrochaetus  Zel.  (71). 

1904.  G.  mwrinus  Giard.  (22). 

1832.  G.  maximus  Ehr.  (18).  1 

1910.  G.  minimus  Marco.  (40). 

1908.  C.  multispinosus  Griin  (26).     Is  C.  tabnlatum  Schm. 
1901.   G.  nodicaudus  Voigt.  (63).      Very  like  G.  entzii  (Dad.). 
1910.   C.  nodifurca  Marco.  (40).     Very  like  G.  entzii  (Dad.). 
1887.  G.  octonarius  Stokes  (57). 

1897.  G.  ornatus  Dad.  (12). 

1910.  C.  paucisetosus  Marco.  (40). 

1889.  C.  persetosus  Zel.  (71).  j 

1909.  C.  ploenensis  Voigt.  (69). 

1905.  C.pusillus  Dad.  (14).  ] 
1887.  C.  rhomboides  Stokes  (57).     Is  probably  0.  entzii  (Dad.). 
1865.  C.  schidtzei  Met.  (41). 

1901.  C.  serraticaudus  Voigt.  (63). 

1889.  C.  similis  Zel.  (71).  | 

1909.  C.  simrothi  Voigt-  (69). 

1887.  C.  spinifer  Stokes  (57).  ] 

1887.  C.  spinidosus  Stokes  (57). 

1864.  C.  slackiae  Gosse  (24). 
1841.  C.  squammatus  Dnj.  (16). 

1902.  C.  snccinctus  Voigt.  (66). 

1887.  C.  sulcatus  Stokes  (57).     Is  an  Ichthydium. 

1908.  C.  tenuis  Griin.  (26). 

1902.  C.  uncinus  Voigt.  (66). 

1908.  C.  zelinhai  Griin.  (26), 

1865.  Chaetura  capricornia  Met.  (41). 
1913.  C.   piscator   Murray.      (Described   in   this  paper  for  first 

time.) 
1851.  Dasydytes  antenniger  Gosse  (23).     Now  the  genus  Gossea. 
1891.  D.  bisetosus  Thomp.  (62). 
i909.  D.  dubiiis  Voigt.  (69). 


J.    MURRAY    ON    GASTROTRICIIA.  221 

1909.  B.festhians  Yoigt.  (69). 

1851.  D.  goniathrix  Gosse  (23). 

1909.  D.  ornatus  Voigt.  (69). 

1910.  D.  pa ucisetosus  Marco.  (40). 
1887.  D.  saltitans  Stokes  (59). 

1901.  D,  stylifer  Yoigt.  (64).     Is  a  Stylochaeta. 

1893.  D.  zelinkai  Laut.  (35).     Seems  to  be  D.  goniathrix  Gosse. 

1886.  Ichthydium  bogdanovii  Schim.  (51).      Is  a  Chaetonotus. 

1905.  /.  crassum  Dad.  (14). 

1908.  /.  cyclocephalum  Griin.  (26). 

1882.  /.  entzii  Dad.  (11).     Is  a  Chaetonotus. 

1901.  I.forcipatum  Voigt.  (64). 

1861.  I .  jamaicense  Schin.  (52).     Is  a  Chaetonotus. 

1897.  /.  macrurum  Collin.  (8). 

1865.  /.  ocellatum  Met.  (41). 

1861.  /.  tabulatum  Schm.  (52).     Is  a  Chaetonotus. 

1908.  /.  tergestinum  Griin.  (26). 

1905.  Gossea  fasciculata  Dad.  (14). 

1905.  G.  pauciseta  Dad.  (14). 

1897.  Lepidoderma  biroi  Dad.  (12).     Is  probably  C.  entzii  (Dad.). 

1905.  L.  elongatum  Dad.  (14).     Is  probably  C.  entzii  (Dad.). 

1910.  L.  hystrix  Dad.  (15).     Is  probably  C.  entzii  (Dad.). 

1890.  Polyarthrafusiformis  Spencer  (56).    Now  genus  Stylochaeta. 

1908.  Setopus  primus  Griin.  (26).   Scarcely  differs  from  Dasydytes. 

1776.  Trichoda  larus  Mull.  (43).     Now  Chaetonotus  larus. 

Identification  of  Species. 

It  was  my  ambition  to  accompany  this  paper  by  a  key  to  all 
the  species  hitherto  described,  so  that  the  student  might  identify 
them  all,  or  at  least  know  what  characters  they  were  supposed 
to  have.  I  found  the  task  beyond  my  powers,  for  not  only  are 
there  a  number  of  descriptions  which  I  have  been  unable  to 
consult,  but  many  of  the  diagnoses  are  such  that  to  make  use 
of  the  characters  given  in  them  would  be  actually  misleading. 

This  is  especially  true  of  negative  characters.  Certain  species 
are  described  as  having  the  body  covered  with  scales,  others  as 
having  some  or  all  of  the  bristles  barbed  or  with  supplementary 
points.  It  must  not  be  assumed  that  species  not  thus  character- 
ised  do   not    possess    those    characters.      Both     are    structures 


222  J.    MURRAY    ON    GASTROTRICHA. 

excessively  difficult  to  see,  and  the  authors  of  species  may  have 
overlooked  them. 

There  is  no  more  definite  character  for  distinguishing  species 
of  Chaetonotus  than  the  form  of  the  dorsal  plates,  if  one  could 
only  see  them,  but  nothing  has  astonished  me  more  than  the 
utter  invisibility  of  those  plates,  till  some  accident,  such  as  finding 
an  empty  skin  or  mutilated  specimen,  has  revealed  them. 

As  I  have  put  some  work  into  the  preparation  of  this  key,  and 
do  not  wish  to  throw  it  away,  I  have  made  some  use  of  the 
material  by  indicating  for  the  genus  Chaetonotus  certain  groups 
of  species  characterised  by  the  possession  of  some  common 
feature. 

Chaetonotus. 

Body  covered  by  Plates  or  Scales. 

G.  acanthodes,  acanthophorus,  arquatus,  brevispinosits,  chuni, 
entzii,  erinaceus,  heterochaetus,  hystrix,  larus,  linguaeformis,  macro- 
chaetus,  maximus,  octonarius,  ornatus,  persetosus,  ploenensis, 
pusillus,  schultzei,  serraticaudits,  similis,  simrothi,  spinifer,  squam- 
matus,  succinctus,  tabidatus,  tenuis,  uncinus,  zelinkai. 

Stated  to  have  no  Plates. 
G.  enormis,  formosus. 

Nothing  said  about  Plates. 

G.  bogdanovii,  dubius,  gracilis,  jamaicense,  longispinosus, 
marinus,  slackiae,  spi?iulosus. 

With  Cephalic  Shield. 

C.  entzii,  erinaceus,  formosus,  maximus,  ornatus,  persetosus, 
pusillus,  schultzei,  tenuis,  zelinkai.  Not  noted  for  the  other 
species. 

Head  not  Lobed. 

G.  bogdanovii,  dubius,  jamaicense,  marinus,  ornatus,   slackiae, 

tabidatus. 

Head  Three-lobed. 

G.  brevispinosits,  chuni,  erinaceus,  formosus,  heterochaetus, 
hystrix,  larus,  linquaeformis,  macrochaetus,  pusillus,  schultzei, 
serraticaudus. 


j.  murray  on  gastrotricha.  223 

Head  Five-lobed. 

C.  acanthophorus,  arquatus,  eno?"mis,  gracilis,  longispinosus, 
maximus,  octonarius,  persetosus,  ploenensis,  similis,  simrothi, 
spinulosus,  squammatus,  succinclus,  tenuis,  uncinus,  zelinkai. 

All  Bristles  with  Supplementary  Points  (Barbs). 
C.  chuni,  erinaceus,  hystrix,  schultzei,  similis,  spinifer. 

Some  Bristles  Barbed. 

C.  acanthophorus,  enormis,  heterochaetus,  longispinosus,  macro- 
chaetus,  octonarius,  persetosus,  spinulosus,  zelinkai.  All  the 
others  are  supposed  to  have  simple  unbranchecl  bristles. 

Having  Series  of  Larger  Thicker  Bristles. 

C.  acanthodes,  acanthophorus,  bogdanovii,  brevispinosus,  dubius, 
enormis,  heterochaetus,  longispinosus,  macrochaetus,  octonarius, 
ornatus,  ploenensis,  persetosus,  similis,  spinifer,  spinulosus,  suc- 
cinctus,  tenuis,  uncinus,  zelinkai. 

Posterior  Bristles  Progressively  Longer  (exclusive  of 
the  larger  bristles  above  noted). 

C.  arquatus,  chuni,  entzii,  erinaceus,  hystrix,  larus,  macro- 
chaetus, ornatus,  pusillus,  schultzei,  similis,  tenuis,  zelinkai. 

Bristles  equal  or  not  Noticeably  Longer  Posteriorly. 

C.  brevispfinosus,  dubius,  formosus,  gracilis,  heterochaetus, 
jamaicense,  linquaeformis,  marinus,  maximus,  serraticaudus,  sim- 
rothi, slackiae,  squammatus,  tabulatus. 

Notes  on  Some  Species  I  have  Seen. 

I  have  in  some  of  my  faunistic  lists  noted  Chaetonotus  larus 
and  Ichthydium  podura,  but  these  records  have  the  same  value 
as  nearly  all  such  records — i.e.  none. 

At  various  times  I  have  made  studies  of  species  which  I  could 
not  identify  with  the  assistance  of  the  literature  at  my  disposal. 
After   reviewing   nearly   all   the  literature,   and    taking  all  tha 


224  J.    MURRAY    ON    GASTROTRICHA. 

diagnoses  at  their  face  value,  it  appears  that  several  of  these 
species  differ  from  any  of  those  described  in  the  works  known 
to  me. 

I  would  have  dealt  with  these  in  the  usual  way  and  described 
them  as  new  species,  but  just  as  I  was  finishing  this  paper  Mr. 
Harring  of  Washington  was  good  enough  to  call  my  attention 
to  a  paper  by  Marcolongo  which  I  had  overlooked  (40).  In  that 
paper  there  are  described  a  number  of  new  species  of  Chaetonotus, 
as  well  as  a  new  family  and  genus. 

Mr.  Harring  has  kindly  transcribed  the  descriptions,  which 
appear  to  be  better  than  such  things  usually  are,  but  as  they 
are  unaccompanied  by  figures  no  certain  identification  is  possible. 
I  consider  all  descriptions  of  animals  in  this  group  unaccompanied 
by  figures  as  insufficient,  but  we  are  promised  figures  in  a  forth- 
coming work  by  the  same  author. 

In  the  circumstances  I  have  no  alternative  but  to  withdraw 
my  new  species  in  the  meantime,  but  there  can  be  no  harm  in 
figuring  and  describing  them  as  animals  I  have  actually  seen. 

Several  of  these  are  figured  on  the  plate,  in  company  with 
others  which  I  do  nob  suppose  to  be  new  species. 

The  species  of  Chaetura  I  can  describe  with  an  easy  mind,  as 
no  one  since  Metchnikoff  has  ever  described  a  species  of  this 
genus. 

Ichthydium  sp.  (PL  19,  fig.  23). 

A  graceful  little  animal,  with  very  slender  neck,  deeply 
trefoliate  head  and  long  furca.  The  branches  of  the  furca 
are  close  together  at  the  base,  and  diverge,  tapering  to  points. 
No  tactile  setae  are  noted,  but  the  animal  probably  had  them. 
Length  about  130  fx. 

Habitat. — Amongst  Sphaynum,  Fort  Augustus,  Scotland,  1904. 

It  is  a  good  deal  like  Joblot's  "  poisson  a  la  tete  faite  en  trefle," 
which  some  have  identified  as  /.  podura.  But  what  was  /.  podura 
like  ?  Various  animals  have  been  figured  by  authors  under  that 
name,  stout  animals  and  thin  animals,  with  long,  slender  furca 
or  with  little  blunt  knobs.  Usually  they  do  not  appear  to  have 
gone  back  to  Miiller,  or  even  to  Ehrenberg,  to  find  what  podura 
was  like.  If  they  had  they  would  have  found  it  was  like  various 
things.     Miiller's  podura  possessed  bristles  (in  some  figures),  and 


J.    MURRAY    ON    GASTROTRICHA.  225 

so  ought  to  go  into  Ehrenberg's  genus  Chaetonotus.  Its  furca 
was  somewhat  like  the  animal  I  have  figured.  Ehrenberg's  had 
a  different  furca. 

Lepidoderma  sp.  (PI.  10,  fig.  29). 

A  very  small  animal,  with  five-lobed  head,  apparently 
rhomboid  scales,  and  a  short  furca  with  diverging  branches. 
Long,  tactile  setae  on  the  head.     Length,   50  to  60  /x. 

The  small  size  might  lead  to  the  supposition  that  the  animal 
is  young.  In  the  only  instance  in  which  I  have  seen  a  Gastrotrich 
hatch  out  of  the  egg  the  young  was  of  the  full  adult  length  of 
the  species.  It  had  only  to  eat  and  fill  out.  From  this  I  suppose 
that  Gastrotricha,  like  many  Rotifera,  do  not  grow  appreciably 
in  length. 

I  say  the  scales  are  "  apparently '  rhomboid,  because  the 
regular  double  diagonal  arrangement  in  rows  might  give  rise 
to  this  appearance  although  the  scales  were  of  some  other 
form. 

Chaetonotus  sp.  (PI.  19,  figs.  SlaSlb). 

Of  medium  size  ;  trunk  oval,  neck  well  marked,  head  slightly 
elongated,  five-lobed,  without  cephalic  shield.  Mouth  nearly 
terminal,  with  tuft  of  hairs. 

The  bristles  on  the  head  and  neck  are  excessively  short  and 
fine.  At  the  front  of  the  trunk  they  become  abruptly  longer 
and  thicker  (though  still  short)  and  progressively  longer 
posteriorly.  Near  the  base  of  the  furca  there  are  some  half- 
dozen  bristles  longer  and  thicker  than  any  others.  None  of  the 
bristles  are  barbed. 

The  scales  from  which  the  hairs  spring  are  elongate  hexagons, 
with  the  angles  so  rounded  off  that  they  are  almost  oval.  They 
are  arranged  in  regular  diagonal  rows,  and  are  separated  at 
their  bases  by  spaces  about  equal  to  the  width  of  the  scales. 

The  furca  is  short,  the  branches  diverging,  then  converging 
(enclosing  a  rhomboid  place),  obtuse. 

No  plates  can  be  seen  on  the  head  or  neck.  It  is  the  only 
species  I  have  seen  in  which  the  scales  are  visible  and  conspicuous 
in  a  specimen  in  good  condition. 

Habitat. — Scotland. 


226  J.    MURRAY    ON    GASTROTRICHA. 

t 

Chaetonotus  entzii  (Dad.)?  (11)  (PL  19,  fig.  26). 

A  large  animal,  250  to  300  jul  and  upwards  in  length.  Head 
obscurely  3-lobed,  with  two  anterior  processes,  and  two  others  at 
posterior  angles.  Body  long,  nearly  parallel-sided,  covered  with 
apparently  rhomboid  scales,  in  diagonal  rows,  and  fine  short  hairs, 
gradually  becoming  longer  posteriorly.  Furca  very  long,  nodose 
(about  twenty  nodes  in  the  length),  widely  divergent  at  base  where 
separated  by  small  sulcus,  less  widely  divergent  above  base. 

Habitat. — Pond  in  the  Praca  Republica,  Rio  de  Janeiro,  Brazil  ; 
several  specimens. 

About  eight  species  of  long-furcate  nodose  Gastrotrichs  have 
been  described,  which  have  all  a  suspiciously  strong  family  likeness. 
Some  of  these  are  certainly  synonymous,  their  authors  being 
unaware  of  the  existence  of  the  other  species.  Daday,  who  is 
responsible  for  the  greater  number  of  them,  professes  to  draw 
distinctions,  but  he  is  not  very  convincing,  and  moreover  I  have 
found  the  animal  here  described  to  be  extremely  variable. 

Daday  first  described  entzii  as  an  Ichthydium,  although  it  had 
the  characters  of  Chaetonotus.  Later  he  described  similar  forms 
as  Lepidoderma,  although  some  of  them  at  any  rate  did  not  fit  his 
genus.  Some  he  compared  with  entzii  and  with  rhomboides  Stokes, 
noting  that  some  had  not  the  spines  on  the  head,  some  had  the 
furca  hairy,  others  smooth,  etc.  I  cannot  pretend  to  sort  oat  all 
of  these  here,  but  content  myself  with  pointing  out  the  family 
resemblance. 

Those  I  found  in  Rio  had  the  hairs  extremely  variable,  in  some 
very  short,  in  others  not  visible  at  all.  I  could  not  doubt  that 
these  were  all  one  species,  as  I  could  see  no  other  differences 
whatever.  The  various  species  having  long  nodose  furca  will  be 
found  noted  in  the  list  of  all  described  species. 

Chaetonotus  sp.  (PI.  19,  fig.  30). 

Large.  Head  short,  5-lobed,  with  cephalic  shield,  neck  slightly 
marked.  Body  clothed  with  simple  hairs  in  about  fifteen  or 
sixteen  longitudinal  rows,  progressively  longer  posteriorly.  Scales 
like  spear-heads,  very  like  those  of  C.  larus  (fig.  9).  The  outline 
of  the  body  appears  crenulate,  with  very  prominent  papillae  in 
the  narrow  part  above  the  furca.     About  eight  longer  setae  close 


J.    MURRAY    ON    GASTROTRICHA  .  227 

to  the  furca,  springing  from  the  papillae.  Fnrca  longish,  widely 
divergent,  obtuse  pointed. 

Habitat. — Praca  Republica,  Rio  de  Janeiro.  The  original  larus 
is  probably  not  now  recognisable,  but  modern  authors  have 
defined  it  as  an  animal  with  scales  as  in  fig.  9,  and  about  eleven 
longitudinal  rows  of  them.  This  has  more  numerous  rows.  As 
far  as  can  be  judged  from  the  description  without  a  figure,  this 
species  is  very  like  C.  laroides  Marco.,  but  that  is  said  to  have  the 
scales  truncate  posteriorly. 

It  is  to  be  noticed  that  these  very  destinctive  scales  are  quite 
invisible  in  living  or  well-preserved  specimens.  I  have  only 
managed  to  see  them  in  empty,  partly  shrivelled  skins. 

Chaetonotus  sp.  (PI.   19,  fig.  34). 

Of  moderate  size.  Head  obscurely  3-lobed,  with  large  cephalic 
shield.  Body  covered  with  long,  widely  out-curved  bristles,  all 
barbed,  in  few  rows  (six  seen  in  dorsal  view)  springing  from 
obscure  but  large  hemispherical  scales.  Close  to  the  furca  nine 
very  long,  recurved,  barbed  bristles,  three  dorsal,  six  lateral. 
Branches  of  furca  long,  separated  by  sulcus  at  base,  outcurved, 
knobbed. 

Habitat. — Sydney  and  New  Zealand  ;  a  very  similar  form  in 
Rio,  Brazil. 

The  most  obvious  character  is  the  widely  spreading  bristles. 
Even  those  nearest  the  cephalic  shield  are  long,  but  they  are 
progressively  longer  posteriorly  till  near  the  furca,  when  a  few 
quite  short  bristles  intervene  between  the  longest  dorsal  bristles 
and  the  special  large  ones  at  the  furca. 

Chaetonotus  sp.  (PI.  19,  fig.  35). 

Of  moderate  size,  relatively  broad  and  squat.  Head  rounded, 
5-lobed.  Neck  well-marked,  short.  Trunk  parallel-sided.  Body 
covered  with  apparently  rhomboid  scales,  each  bearing  a  short 
spine  or  scale.  Furca  short,  diverging,  then  converging  (enclosing 
a  rhomboid  space),  the  basal  portion  scaly,  the  apical  portion 
smooth.     There  are  long  tactile  setae  on  the  head. 

The  general  form  is  like  that  of  Ichthydium  ocellatum  Met. 
[Lepidodei'ma  ocellatum  Zel.).  I  saw  nothing  like  the  eye-spots 
ascribed  to  both  those  animals. 


228  J.    MURRAY    ON    GASTROTRICHA. 

As  there  are  no  type  specimens,  and  only  MetchnikofTs  descrip- 
tion to  go  by,  there  is  no  justification  for  transferring  his  species 
to  the  genus  Lepidoderma,  as  Zelinka  does.  It  is  either  an 
Ichthydium  Ehr.  or  insufficiently  described  and  unrecognisable. 

Zelinka's  animal  may  be  the  one  which  I  here  figure.  If  so 
it  seems  to  me  that  the  little  triangular  scales  or  spines  are 
homologous  with  the  bristles  of  Chaetonotus,  and  not  with  the 
scales  of  Lepidoderma,  and  so  it  should  be  placed  in  the  former 
genus. 

Habitat. — Summit  of  Ben  Lawers,  Scotland,  among  moss,  1905. 

Chaetura  piscator  sp.  now  (PI.   19,  fig.  33). 

Specific  characters. — Small ;  head  elongate,  egg-shaped,  fringed 
with  long  setae ;  neck  moderately  constricted ;  body  spindle- 
shaped  ;  each  branch  of  furca  forked,  branches  equal ;  trunk 
bearing  at  least  four  longitudinal  series  of  fine  bristles  shaped  like 
fish-hooks,  and  some  straight  setae  near  the  furca. 

General  description. — Length  150  /x,  head  50  /x  long  by  36  /x 
wide,  trunk  30  fx  wide,  branches  of  furca  about  12  jx  ;  hooks 
project  about  15  fx  above  the  surface. 

The  head  is  the  widest  part  of  the  body.  It  is  fringed  by  long 
straight  hairs  or  setae,  and  bears  some  larger  movable  setae  which 
appear  to  have  a  tactile  function.  The  neck  is  slightly  constricted, 
but  has  a  swelling.  The  dorsal  hairs  are  shaped  exactly  like  fish- 
hooks, without  their  barbs.  They  spring  out  at  nearly  right 
angles  to  the  skin,  curve  round  in  the  posterior  direction,  and 
nearly  touch  the  skin  at  their  tips.  I  distinguished  four  rows 
of  them,  but  in  dealing  with  such  excessively  fine  structures 
it  is  not  well  to  state  hard-and-fast  numbers.  Four  of  the 
straight  setae  could  be  seen  dorsally,  close  by  the  tail ;  the  four 
branches  of  the  furca  are  nearly  equal,  slightly  curved,  and  have 
blunt  tips. 

Technically  this  is  a  Chaetura,  having  the  branches  of  the  furca 
furcate,  although  in  MetchnikofTs  type  species,  G.  capricornia, 
they  are  not  properly  furcate,  but  bear  little  branches  on  the 
inner  side.  As  in  the  type,  the  head  is  broader  than  the  trunk 
and  there  are  stiff  bristles  over  the  tail.  The  fishhook-like  setae 
distinguish  it  from  all  other  known  Gastrotrichs. 

Habitat. — Amongst  moss,  Shetland  Islands,  1906. 


j.  murray  on  gastrotricha.  229 

Bibliography. 

An  asterisk  *  indicates  works  in  which  new  species  are  described. 

The  works  of  any  importance  number  scarcely  more  than  a 
dozen.  They  are  Ehrenberg,  1838  (19);  Gosse  1851  (23),  and 
1864  (24);  Metcbnikoff  1865  (41);  Stokes  1887  (57);  Daday 
1882  (11),  1901  (13),  1905  (14),  1910  (15);  Zelinka  1889  (71); 
Giard  1904  (22);  Yoigt  1904  (68);  Griinspan  1909  (26);  Collin 
1912  (9). 

With  these  works  the  student  will  have  everything  he  requires, 
except  a  few  descriptions  of  doubtful  new  species. 

Ehrenberg,  1838,  summarises  the  work  of  the  pioneers,  and 
originates  a  classification.  Fraulein  Griinspan,  1909,  gives  the 
fullest  systematic  account  of  the  group.  Zelinka,  1889,  is  far  and 
away  the  best  work  on  the  subject,  being  a  painstaking  and 
minute  study  ;  but  much  has  been  added  to  our  knowledge  since  his 
memoir  appeared.  Collin,  1912,  is  simply  a  compilation,  but  a 
useful  one.  The  others  noted  above  are  the  principal  systematic 
works,  containing  descriptions  of  many  species. 

1.  Archer,  W.     In  Quart.  Joum.  Micr.  ScL,  14,  p.  106,  1874. 

Exhibited  at  Dubl.  Micr.  Club,  C.  maximus,  C.  gracilis, 
and  D.  antenniyer ;  all  found  in  Ireland.  Note  that  the 
last  species  can  elevate  and  depress  its  antennae. 

2.  Barrois,  T.     Comptes  rendus,  July  1887.     Trans,  in  Ann. 

Mag.  Nat.  Hist.,  xx.,  p.  365,  1877. 

A  segmental  worm,  having  the  appearance  of  Ichthy- 
dium,  but  differing  much  in  structure.  Probably  related 
to  Hemidasys,  Turbanella,  Zelinkia,  Philocyrtis,  which  are 
not  Gastrotricha. 

3.  Bory  de  St.  Vincent.     Encycl.  method.,  Paris,  1824. 

Furcocerca  podura  ( =  Ichthydium)  ;  Zeucophrya  larus 
( =  Chaetonotus). 

4.  Ibid.     Essai  des  micr.,  1826. 

Diceratella  larus  (  =  Chaeto?iotus). 

5.  Bryce,   D.     In  letter  to  Fraulein  Griinspan  (vide  26,  p.  228). 

Records  C.  zelinkai  for  England  and  Scotland. 

6.  Butschli,  O.     Freilebende  Nematoden  u.  d.  Gattung  Chae- 

tonotus.    Zeit.  fur  wiss.  Zool.,  26,  pp.  385,  390,  etc.,  1876. 
Classification  and  Anatomy.     Good  structural  figures  of 
C.  maximus  and  C.  larus. 


230  J.    MURRAY    ON    GASTROTRICHA. 

7.  Claparede,  E.     Misc.  zool.  III.  nouveau  genre   de  Gastero- 
triches.     Ann.  Sci.  Nat.,  Ser.  5,  vol.  8,  p.  18,  1867. 

Hemidasys  agaso  gen.  et  sp.  nov.  Not  a  Gastrotrich,  I 
think. 

*8.  Collin,  A.     Rot.  Gastro  u.  Entoz.  Deutsch  Ost-Afrika,  4,  p.  9, 
1897. 

/.  macrurum  sp.  n.  A  somewhat  meagre  description, 
from  figure  drawn  by  Stuhlman. 

9.  Ibid.       Gastrotricha.       In    Susswasserfauna     Deutschlands, 
pp.  240-65,  figs.  475-507. 

A  good    account   of   thirty-two   German    species,   with 
many  useful  figures.     No  new  species. 
10.  Corti.     Osser.  micr.  sulla  Tremetta,  p.  89,  PI.  2,  1774. 

Ehrenberg  thirks  the    "  animaluzzo  molle  "   may   have 
been  C.  maximus.     I  have  not  seen  the  work. 
*11.  Daday,  E.     Ichthydium  entzii. 

Termes.  Fiiz.,  pp.  231-52,  PI.  3,  1882. 

New  species  ;  full  description  and  good  figures.  Seems 
to  be  the  first  appearance  of  a  much-described  animal 
which  is  almost  certainly  the  same  as  Stokes'  C.  rhom- 
boides,  and  is  probably  also  Yoigt's  C.  nodicaudus 
and  Daday's  own  L.  hystrix,  L.  elongatum  and  L.  biroi, 
as  well  as  C.  macracanthus  Laut.  I  found  the  animal 
in  Rio  de  Janeiro,  and  noted  that  the  dorsal  hairs 
vary  greatly  in  length  and  may  be  absent,  so  that 
the  species  is  both  Chaetonotus  and  Lepidoderma  on 
occasion  ! 

*12.  Ibid.     Uj-Guineai  Rotatoriak.      Math.   es.    Termes.  Ertes., 
vol.  15,  pp.  145-48.     (In  Hungarian.)     1897. 
New  species — C.  orno.tus  and  L.  biroi. 

13.  Ibid.      Mikr.     Siisswasserthiere   aus    Deutsch   Neu-Guinea. 
Termes.  Filz.,  24,  56  pp.,  3  plates,  1901. 

Description  and  figures  of  the  two  new  species  of  his 
previous  paper  (1897). 

*14.  Ibid.     Susswasser-mikrofauna    Paraguays.      Zoologica,    18, 
pp.  72-86,  Pis.  5-6,  1905. 

Eight  new  species — I.crassum,  L.  elongatum,  C.pusillus, 
C.  dubius,  C.  erinaceus,  C.  heterochaetus,  G.  fasciculata, 
G.  paaciseta. 


J.    MURRAY    ON    GASTROTRICHA.  231 

*15.  Ibid.      Susswasser-mikrofauna   Deutsch   Ost-Afrikas.     Zoo- 
logica,  23,  pp.  56-9,  PI.  3,  1910. 
New  species — L.  hystrix. 
*16.  Dujardin,  F.     Hist.  nat.  des  Zoophytes  Infusoires,  pp.  515- 
69,  PL  18,  figs.  7-8,  1841. 

New  species — C.  squamniatus. 
17.  Ibid.      Sur  un  petit  animal  marin  (l'Echinodere).     Ann.  Sci. 
Nat.,  Ser.  3,  vol.  15,  p.  158,  PI.  3,  1851. 
Once  classed  with  the  Gastrotricha. 
*18.  Ehrenberg,  C.  J.     Organ,  in  d.  Richtuny  d.  kleinsten  Raumes, 
2nd  Part,  Berlin,  1832. 

Descriptions   (perhaps    not    his   earliest)   of   /.  podura, 
C.  maximus,  C.  larus,  C.  breve. 

19.  Ibid.     Die  Infusionsthierchen,  pp.  386-90,  1838. 

Redescribes  the  same  four  species  as  in  1832. 

20.  Eichhorx,  I.  C.     Naturgeschichte  der  kleinsten   Wasserthiere, 

p.  35,  PI.  2,  fig.  r,  1781. 
Probably  a  Chaetonotus. 

21.  Florentin,  R.     Faune   des   mers    salees.      Ann.    Sci.    Nat. 

(Ser.  8),  10,  p.  272,  1899. 

Records  Lepidoderma  ocellatam  from  salt  water. 
*22.  Giard,  A.     Faunule  caracteristique  des  sables  a  Diatomees. 
C.  R.  Soc.  Biol,  pp.  1061-5,  1904. 

New  species — C.  marinus.     Also  new  genera  Zelinkia 
(sp.  Z.  plana)  and   Philocyrtis  (sp.    P.  monotoides),  which 
are  very  doubtful  Gastrotricha. 
*23.  Gosse,  P.  H.     A  Catalogue  of  Potifera  found  in  Britain. 
Ann.  Mag.  Nat.  Hist.,  Ser.  2,  vol.  8,  p.  198,  1851. 

New  genus  Dasydytes,    and  new  species  D.   goniathrix 
and  D.  antenniger ;  no  figures.     Saccidus  viridis  described 
as  a  Gastrotrich. 
*24.  Ibid.       The   hairy-backed    Animalcnli.       Intell.    Obs.,    V., 
pp.   387-406,  2  plates,   1864. 

New  species — C.  slackiae,  C.  gracilis. 
Taphrocampa  new  genus,  described  as  a  Gastrotrich. 
25.  Grimm,  O.  A.     Fauna  im   baltischen   Meere  (is   a   German 
rendering  of  the  Russian  title).     Arb.  d.  St.  Peter.  Naff 
Ges.,  8,  p.  107,  1877. 

Gastrochaeta  ciliata  new  genus  and  species.     No  figure 
given.     In  a  footnote  he  compares  the  animal  with  various 


232  J.    MURRAY    ON    GASTROTRICHA. 

species    of    Desmoscolex,    so   it    is     probably  not   a  true 
Gastrotrich. 
*26.  Grunspan,  Therese.     Systematik  cler  Gastrotrichen.     Zool. 
Jahrb.,  pp.  214-56,  1908. 

A  comprehensive  synopsis  of  all  known  species.  Seventy 
admitted  species  ;  six  new  species  and  a  new  genus — /.  terges- 
tinum,  I.  cyclocephalum,  C.  zelinkai  (and  var.  gra.censis),  C. 
tenuis,  C.  midtispinosas,  Setoptcs  primus(gen.  et  sp.  nov.). 

27.  Ibid.  Die  SUsswasser-Gastro-trichen  Europas.     Eine  zusam- 

menfassende  Darstellung  ihrer  Anatomie,  Biologie  und  Sys- 
tematik. Ann.  Biol.  Lacustre,  Bruxelles,  vol.  4,  pp.  21 1— 365? 
61  figs. 

28.  Hartog,     M.        Rotifera    Gastrotricha    and    Kinorhynchia. 

Cambridge  Nat.  Hist.,  vol.  2,  p.  232,  etc.,  1896. 

A  good  account  and  figures  of  seven  known  species. 

29.  Heinrich  u.  Ehrenberg.     Symbolae  physicae.     Evertebrata. 

I.  Phytozoa,  Plates.     Berlin,  1828;  text,  1831. 

PI.  I.,  fig.  11,  Diurella  podura  (=  Ichthydium). 
*30.  Hlava,    S.     Syst.    Stell.   v.   Polyarthra  fusiformis  Spencer. 
Zoo.  Anz.,  28,  pp.  8-9,  December  1904. 

New  genus  Stylochaeta  (sp.  S.  fusiformis  Spencer). 

31.  Imhof,  0.     Tiefseefauna — SUsswasserbecken.     Zoo.  Anz.,  8, 

p.  325,  1885. 

Found  C.  maximus  as  an  abyssal  species  in  lakes. 

32.  Joblot.     Nouvelles  Observations,  p.  79,  PI.  10,  fig.  22,  1718. 

"  Poisson  a  la  tete  faite  en  trefle  "  ( =  /.  podura). 

33.  Kojevnikof,    G.        Faune    de    la    mer    Baltique    orientale. 

•  Congres  intern.  Zool.  II.,  Moscow,  pp.  132-57,  1892. 
I  have  been  unable  to  find  this  work. 

34.  Lamarck.     Hist.  nat.  des  Animaux  sans  vertebre,  p.  447,  1850. 

Furcocerca  podura  (  =  Ichthydium). 
*35.  Lauterborn,   R.      Rot. -Fauna  d.   Rheins  u.   s.   Altwasser. 
Zool.  Jahrb.,  7,  Syst.,  pp.  1^54-73,  PI.  11,  1893. 

New  species — Dasydytes  zelinkai,  C.  mawacanihus .  The 
description  shows  D.  zelinkai  as  a  not  very  distinct  variety 
of  D.  goniathrix  Gosse.  No  figure  is  given.  C.  macra- 
canthus  appears  to  be  C.  entzii  Dad. 
36.  Ibid.  Die  sapropelische  Lebewelt.  Zoo.  Anz.,  24,  pp.  50-55, 
1901. 

Dasydytes  zelinkai  (see  previous  paper). 


J.    MURRAY    ON    GASTROTRICHA.  233 

37.  Lucks,  R.   Linaugebiet    micr.-Wasserbewohner.    Jahrb.  West- 

preuss.  Lehrver.f.  Naturk.,  pp.  20-23  (1905),  1906. 
List  of  eight  known  species  in  West  Prussia. 

38.  Ibid.     Neues  aus  d.  Mikrofauna  Westpreussens.     Ber.  West- 

preuss.  Bot.-Zool.  Ver.,  31,  pp.  141-2,  1909. 

Three  additional  known  species  in  West  Prussia. 

39.  Ludwig,   K.     TJ.   d.   Ordnung  Gastrotrichs.     Zeit.  far  iviss. 

Zool.,  26,  pp.  219-25,  1875. 

A  general  work,  dealing  with  systematic  position,  etc. 
List  of  thirteen  known  species. 
*40.  Marcolongo,  I.     Primo  contributo  alio  studio  dei  Gastro- 
trichi  del  lago-stagno  craterico  di  Astroni.     Monitore  Zool. 
Ital.  Firenze,  21,  pp.  315-18,  1910. 

He  gives  no  figures,  but  describes  a  new  family 
Anacanthodermidae,  a  new  genus  linacanthoderraa,  and 
eight  new  species — Chaetonotus  laroides,  C.  hirsutus,  C. 
minimus,  C.  nodifarca,  C.  decemsetosus,  C.  2)aucisetosus, 
Dasydytes  imucisetosus,  Anacanthoderma  punctatum. 

I  have  not  seen  this  paper,  but  received  these  particulars 

by  favour  of  Mr.  Harring,  of  Washington.    (Vide  No.  72.) 

*41.  Metchnikoff,  E.       Wenig-bekannte  niedere    Thierformen. 

Zeit.  fur  wiss.  Zool,  4,  pp.  450-8,  PI.  15,  1865.     English 

trans,  in  Journ.  Jlicr.  Sd.  (N.S.  6),  pp.  241-52,  1865. 

New   genera — Chaetura    (sp.    capr worms),    Cephalidium 
(=  Dasydytes)  (sp.  longisetosum).       New   species — Ichthy- 
dium  oceUatum,  C.  hystrix,  C  schultzei. 
*42.  Muller,  O.  F.      Verm.  terr.  etfluv.,  pp.  66  and  79,  1773. 

New  species — Cercaria  podura  (=  Ichthydiam),  Trichoda 
acarus  and  T.  anas  (both  now  =  C.  larus). 
*43.  Ibid.     Prod.  Zool.  Dan.,  1776. 

Trichoda  lai'us  (  =  Chaetonotus). 

44.  Ibid.     Anim.  infus.fluv.  et  marina,  1786. 

Trichoda  larus  (—  Chaetonotus). 

45.  Nitzsch.     Infusorienkunde,  1817. 

Enchelys  podura  ( =  Ichthydium). 

46.  Norrikov,  A.    Y.     K.   sistematikie   Gastrotiicha    (Russian). 

Triid.  Obs.  Ahklim.  Moskau,  6,  1907,  pp.  309-47,  PI.  10. 

I  have  not  seen  this  paper,  but  Mr.  Harring,  who  kindly 
furnished  the  reference,  says  it  is  largely  a  translation  of 
Zelinka's  paper  (71)  and  contains  little  that  is  new. 
Journ.  Q.  M.  C.,  Series  II.— No.  73.  16 


234  J.    MURRAY    ON    GASTROTRICHA. 

47.  Parsons,   F.   A.     In  the  Quekett  Journal    for  1896-7  there 

occur  some  records  of  Gastrotricha  found  at  the  excursions 
of  the  Club.  I  do  not  know  who  made  the  actual  iden- 
tifications, but  the  records  are  referred  to  in  Mr.  Parsons's 
name  by  various  authors. 

48.  Perrier,  E.     Traits  de  Zoologie,   Fasc.  4,  pp.    1534-9,  figs. 

1103-5,  1897. 

A  general  account  of  six  species,  with  some  figures. 

49.  Perty,  M.     Kleinste  Lebensfovmen  dev  Schweiz,  p.  47,  1852. 

A  few  remarks  on  the  group  and  several  known  species. 

50.  Pritchard,  A.     History  of  Infusoria,  1861. 

The   earlier   editions  of  Pritchard  contain  a  few  notes 
after  Ehrenberg.     In   1861   there  is  a  fair  account  of  the 
group. 
*51.   Schimkewitsch,  W.  M.     Neue  Species  Ichthydium.     Nachr. 

K.  Ges.  Freunde  d.  Natuv.,  50,  1886  (/.  bogdanovii). 
*52.  Schmarda,  L.  K.     Neue  wivbellose  Thieve,  i.  2,  1861. 

Describes  two  new  species  as  Ichthydium — /.  jamaicense 
and  /.  tabulatum — which  are  technically  Chaetonotus, 
according  to  his  own  generic  definition  of  Ichthydium. 

53.  Schrank,  P.  v.  P.     Beitvdge  ficv  Natuvgeschichte,  1776. 

His  Bvacliionus  pilosus  (Part  III.,  PI.  4,  fig.  32)  is, 
according  to  Dujardin  (16,  p.  570,  footnote),  Chaetonotus 
lav  us. 

54.  Ibid.     Fauna  Boica,  hi.,  pp.  90-91,  1803. 

Tvichoda  lavus  (  =  Bvacliionus  pilosus),  T.  anas. 

55.  Schultze,    M.      Ueber    Chaetonotus  mid    Ichthydium    Ehr. 

Avcli.  f.  Anat.  u.  Phys.,  vi.,  pp.  241-54. 

New    genus     Tuvbanella,    which     I     believe    is    not    a 
Gastrotrich. 
*56.  Spencer.     On  a  new  Rotifer,  Polyavthva  fusifovmis. 

This  is  a   Gastrotrich,   since   made   the   type  of  a  new 
genus,  Stylochaeta,  by  Hlava  (30).    J.  Q.  M.  C,  1890,  p.  59. 
*57.  Stokes,  A.   C.     Observations  on  Chaetonotus.     The  Micro- 
scope (American),  vol.  7,  two  parts,  January  and  February, 
1887,  pp.  1-9,  PI.  1  ;  pp.  33-43,  PI.  2. 

One  of  the  most  considerable  works  on  the  group,  in 
which  a  great  many  new  species  are  described.  They  are 
all  regarded  as  Chaetonotus,  the  earlier  generic  distinctions 
not  being  admitted. 


J.    MURRAY    OX    GASTROTRICHA.  235 

New  species — 0.  sulcatus,  C.  concinnus,  C.  loricatus, 
C.  rhomboides,  C.  spinifer,  C.  acanthodes,  C.  octonarius, 
C.  spinulosus,  C.  longispinosus,  C.  enormis,  C.  acantho- 
jjhorus. 

Apparently  good  figures  are  given  of  all  of  these  species, 
and  of  species  of  other  authors,  but  Stokes  claims  indul- 
gence for  inaccuracies  in  all  his  figures. 
58.  Ibid.  Observations  sur  les  Chaetonotus.  Journ.  de  Microg., 
II,  3  parts,  February,  April,  December,  1887,  pp.  77-84, 
150-3,  560-6,  PI.  1  and  2. 

Simply  a  translation  of  the  American  paper,  with  the 
same  plates. 
*59.  Ibid.       Observation    on    a    new    Dasydytes     and    a    new 
Chaetonotus.  The  Microscope,  vol.  7,  pp.  261-5,  1  PI.,  1887. 
New  species — D.  saltitans,  C.  formosus. 
60.  Ibid.     Observations  sur  les  Chaetonotus  et  les   Dasydytes. 
Journ.  de  Microg.,  12,  2  parts,  January,  1888. 
A  translation  of  the  preceding  paper. 
*61.  Tatem,  T.  G.     New  Species  of  Microscopic  Animals.     Quart. 
Journ.  of  Micr.  Sci.,  N.S.  7,  pp.  251-2,  1867. 
New  species — Chaetonotus  longicaudatus. 
*62.  Thompson,   P.  G.     A   new   species   of   Dasydytes.     Science 
Gossip,  No.  319,  1891. 
New  species — D.  bisetosus. 
*63.  Yoigt,    M.       Bisher    unbekannte      Siisswasserorganismen. 
Zool.  Anz.,  xxiv.,  No.  640,  pp.  191-4,  1901. 

New  species — Chaetonotus  serraticaadus,  C.  nodicaudus. 
*64.  Ibid.      Unbesehriebene '  Organ.     Plon.    Gewassern.       Zool. 
Anz.,  xxv.,  No.  660,  pp.  35-9,  1901. 

New  species — Ichthydium  forcipatum,  Chaetonotus-  chuni, 
Dasydytes  stylifer. 
*65.  Ibid.     Rot.  u.  Gast.  d.  Umgebung  v.  Plon.  Zool.  Anz.,  xxv., 
No.  692,  pp.  673-81,  1902. 

He  names  nine  species  as  new,  but  gives  no  descriptions 
or  figures  except  of  one.  Eight  of  them  had  been  de- 
scribed in  earlier  papers.  The  nine  names  are  Ichthydium 
forcijxitum,  Aspidonotus  paradoxus  (n.  gen.,  n.  sp.),  Chae- 
tonotus linguaeformis,  C.  nodicaudus,  C.  serraticaudus,  C. 
uncinus,  C.  succinctus,  C.  chuni,  Dasydytes  stylifer.  He 
describes  Aspidonotus  and  (p.  681)  figures  one  scale. 


236  J.    MURRAY   ON    GASTROTRICHA. 

*66.  Ibid.     Drei  neue  Ohaetonotus-Arten  a.   Plon.   Gew'assern. 
Zool.  Anz.,  xxv.,  No.  662,  pp.  116-18,  January,  1902. 
New  species — C.  linguaeformis,  C.  succinctus,  C.  uncinus. 

*67.  Ibid.  Erne  neue  Gastrotrichenspecies  (Chaetonotus  arquatus) 
aus  dem  Schlossparkteiche  zu  Plon.  Forschber.  Biol.  Stat. 
Plon.,  x.,  pp.  1-4,  1903. 

68.  Ibid.  Rotatorien  u.  Gastrotrichen  d.  TJmgebung  von  Plon. 
Ploner  Forsch.-ber.,  xi.,  180  pp.,  1904. 

He  records  twenty-three  species  and  describes  nine  as 
new,  but  these  have  been  described  in  earlier  papers.  He 
renames  the  genus  he  had  called  Aspidonotus,  making  it 
Aspidiophorus,  as  he  found  that  the  former  name  was 
preoccupied. 

*69.  Ibid.  Nachtrag  zur  Gastrotrichen-Fauna  Plons.  Zool. 
Anz.,  xxxiv.,  No.  24/25,  pp.  717-22,  1909. 

New  species — Chaetonotus  ploenensis,  C.  simrothi,  Dasy- 
dytes  dubius,  D.  festinans,  D.  ornatus. 

70.  Wagner,  F.  Der  Organismus  der  Gastrotrichen.  Biol. 
Centralb.,  3,  No.  7/8,  1893. 

•71.  Zelinka,  C.  Die  Gastrotrichen.  Zeit.  f.  iviss.  Zool.,  49, 
pp.  299-476,  PI.  11-15,  1889. 

An  important  paper,  the  most  careful  and  scientific 
that  has  appeared  on  the  subject.  He  gives  a  good  and 
full  account  of  the  anatomy,  a  good  bibliography,  and  a 
good  resume  of  all  the  systematic  work  on  the  group, 
quoting  most  of  the  authors'  original  descriptions.  Some 
previously  described  species  escaped  his  notice,  as  Ichthy- 
dium  entzii  Dad.  Two  new  genera  and  four  new  species 
are  described.  The  genus  Gossea  is  framed  to  contain 
Gosse's  Dasydytes  antenniger,  Lepidoderma  for  Dujardin's 
Chaetonotus  squammatus,  with  C.  rhomboides  Stokes, 
Ichthydium  ocellatum  Metch.,  and  C.  concinnum  Stokes. 
Lepidoderma  is  an  unfortunate  genus,  as  the  type  species 
(C.  squammatus  Duj.)  is  spiny  and  a  true  Chaetonotus.  C. 
rhomboides  Stokes  is  usually  spiny,  and  /.  ocellatum  Metch. 
is  not  stated  or  figured  by  its  discoverer  to  have  scales. 

The  new  species  are— Chaetonotus  similis,  C.  brevi- 
spinosus,   C.  Qiiacrochaetus,   C.  persetosus. 

72.   Marcolongo,  Ines.     I  Gastrotrichi  del  lago-stagno  craterico 
di  Astroni.     Atti  Ace.  Sci.  Fio.  e  Nat.  Napoli,  vol.  14. 


J.    MURRAY    ON    GASTROTRICHA.  237 


Explanation  of  Plate  19. 

Scale  and  hair  of  : 
Fig.    1.     G.  macrochaetus  Zel.     (After  Zelinka.) 


55 
?5 
55 
55 
?5 
55 
55 
55 
55 
55 

55 

55 
55 
55 
55 
55 
?> 
fl 
55 
55 
)5 
55 


9 


6'.  hystrix  Metsch. 

3.  C.  si?nilis  Zel.     (After  Zelinka.) 

4.  C.  maximus  Ehr.     (After  Zelinka.) 

5.  G.  persetosus  Zel.     (After  Zelinka.) 

6.  G.  pusillus  Dad.     (After  Daday.) 

7.  C  heterochaetus  Dad.     (After  Daday.) 

8.  C.  schidtzei  Metch.     (After  Zelinka.) 

9.  G.  larus  Miill.     (After  Ludwig.) 
10.     C.  erinaceus  Dad.     (After  Daday.) 

11  a.  G.  succinctus  Voigt,   one  of  the  long   bristles.      (After 

Voigt.) 
116.   C.  succinctus  Yoigt,  scale  from  posterior  part.     (After 

Voigt.) 

12.  G.  hystrix  Metsch.     (After  Zelinka.) 

13.  C.  nodicaudus  Voigt.      (After  Voigt.) 

14.  Aspidiophor us  paradoxus  Voigt.     (After  Voigt.) 

15.  Lepidoderma  ehngata  Dad.     (After  Daday.) 

16.  C.  brevispinosus  Zel.     (After  Zelinka.) 

17.  C.  arquatus  Voigt.     (After  Voigt.) 

18.  G.  simrothi  Voigt.     (After  Voigt.) 

19.  G.  zelinkai  Grim.      (After  Griinspan.) 

20.  C.  uncinus  Voigt.     (After  Voigt.) 

21.  G.  chuni  Voigt.     (After  Voigt.) 

22.  C.  linyuaeformis  Voigt.     (After  Voigt.) 


23.  Ichthydium  sp.  (?). 

24.  Lepidoderma  loricata  Stokes.     (After  Stokes.) 
25a.  Dasydytes  goniathrix  Gosse.     Drawn  from  nature. 
256.   D.  goniathrix  Gosse.     A  single  seta. 

26.  C.  entzii  Dad.  (?).     Differs  from  Daday's  in  having  the 
furca  without  hairs. 

27.  Dasydytes  bisetosus  Thomp.     Drawn  from  nature. 
28a.  Gossea  antennigera  Gosse.     Drawn  from  nature. 
286.   G.  antennigera  Gosse.     Scale  and  hair. 

?,  29.     Lepidoderma,  very  small  species.     Drawn  from  life. 


238  J.    MURRAY    ON    GASTROTRICHA. 

Fig.  30.     Chaetonotus  sp.  (?).     Scales  as  in  C.  larus  (fig.  9),  but 
rows  more  numerous. 
31«.   Chaetonotus  sp.  (?).  With  very  distinct  rhomboid  scales. 
316.    Chaetonotus  sp.  (?).     Three  of  the  scales. 

32.  Setopus  primus  Griin.     (After  Griinspan.) 

33.  Chaetura  piscator  sp.  n. 

34.  Chaetonotus  sp.  (?).     All  hairs  long,  widely  spreading. 

35.  Chaetonotus  or  Lepidoderma.  Like  the  animal  figured 
by  Zelinka  as  L.  ocellatam  Met.,  but  I  saw  no 
eyelike  bodies.  Metchnikoff  did  not  describe  his 
animal  as  scaly. 

,,    36.     Scales  of  C.  tenuis  Griin.     (After  Griinspan.) 


Journ.  Qvekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  73,  November  1913. 


Ser.  2,  Vol.  XII.,  PI.   19. 


J.  Murray,  del.  adnat. 


Gastrotricha. 


239 


NOTES 

ON    A    NEW    METHOD    OF   MEASURING    THE 
MAGNIFYING  POWER  OF  A  MICROSCOPE. 

By  Edward  M.  Nelson,  F.R.M.S. 

{Read  June  2Wi,  1913.) 

Many  microscopists,  at  one  time  or  another,  will  have  experienced 
some  trouble  about  the  determination  of  the  combined  magni- 
fying powers  of  their  objectives  and  eyepieces.  Some  never 
measure  them  at  all,  and  rely  upon  the  manufacturer's  catalogues 
for  the  results.  This  is  not  very  satisfactory,  for  neither 
objectives  nor  eyepieces  turn  out  to  be  at  precisely  their  nominal 
foci  ;  and  if  both  these  should  happen  to  be  either  in  excess  or 
deficit  the  actual  magnifying  power  will  differ  considerably  from 
that  given  in  the  catalogue.  Therefore  it  will  be  better  for  every 
one  to  measure  the  magnifying  powers  of  the  lenses  of  their 
microscope. 

There  are  two  well-known  methods  of  doing  this.  The  first, 
and  perhaps  the  simplest,  is  to  employ  a  photomicrographic 
camera  to  measure  the  magnified  image  of  the  stage  micro- 
meter when  projected  on  to  the  ground  glass  at  a  distance  of  ten 
inches.  The  second  is  to  project  the  magnified  image  of  the 
stage  micrometer,  by  means  of  some  sort  of  a  camera  lucida,  on  to 
a  scale,  distant  ten  inches  as  before. 

All  this  appears  delightfully  simple,  but  w^hen  examined  more 
carefully  it  is  not  really  so.  First,  the  photomicrographic-camera 
method  requires  a  dark  room,  or  the  measurement  must  be  made 
at  night,  and  of  course  it  is  sure  to  happen  that  when  the 
camera  is  most  wanted  it  is  not  available.  This  is  just  what  has 
occurred  to  me.     My  photomicrographic  camera  and  stand,  which 


240     E.  M.  NELSON  ON  A  NEW  METHOD  OF  MEASURING  THE 

are  large  and  heavy,  are  packed  away ;  it  would  take  some 
hours  to  unpack  them,  clear  out  a  room  for  their  reception, 
bring  them  in  and  set  them  up,  so  I  have  to  be  content  with 
some  other  means  of  measuring  magnifying  powers. 

The  second  method,  viz.  that  of  employing  a  camera  lucida, 
also  appears  to  be  very  simple,  and  so  it  is  when  a  Powell  No.  1 
stand  is  used,  which  has  its  optic  axis  ten  inches  from  the  table, 
when  inclined  horizontally ;  a  Beale's  neutral  tint  fitting  on  the 
"  capped"  eyepieces  answers  perfectly — some  attention,  however, 
is  necessary  to  regulate  the  illumination,  both  in  the  tube  and  on 
the  rule,  otherwise  the  coincidences  of  the  lines  cannot  be 
observed.  But  suppose  a  continental  eyepiece  is  used,  what 
then  ?  The  Beale  camera  will  not  fit,  and  all  the  simplicity  of 
one's  arrangements  and  apparatus  fails.  If  the  microscope  is 
not  a  Powell's  No.  1,  then  it  must  be  placed  upon  a  box,  and  the 
distance  of  the  rule  adjusted  by  means  of  other  boxes,  books, 
etc.  With  a  Continental  microscope  matters  are  no  better.  One 
has  the  simplicity  of  the  Abbe  camera,  with  its  cleverly  planned 
device  for  regulating  the  illumination  of  the  stage  micrometer 
and  of  the  rule,  but  suppose  the  eyepiece  is  of  the  positive  com- 
pensating type,  what  is  to  be  done  ?  The  camera  will  not  fit 
and  cannot  be  used.  There  are  other  cameras,  both  of  the  right- 
angled  and  of  the  oblique  type  ;  some  eyepieces  they  fit  and 
others  they  do  not.  These  difficulties  are  not  imaginary,  for 
I  have  experienced  all  of  them  at  one  time  or  another.  The 
apparatus  I  now  use  is  the  old-fashioned  Wollaston's  camera, 
mounted  on  a  table  screw  clamp.  This  can  be  used  with  every 
kind  of  eyepiece  ;  it  is,  however,  troublesome  to  work  with,  and 
it  requires  some  practice  to  obtain  a  coincidence  of  the  scales — 
how  anybody  can  execute  a  drawing  with  such  an  apparatus  is, 
to  me,  quite  incomprehensible  ! 

I  have  devised  an  entirely  new  method  by  which  all  these 
worrying  little  troubles  may  be  avoided.  First,  it  is  necessary 
to  determine  the  "  constant  "  of  the  eyepiece  with  a  given  tube 
length.  This  is  easily  done,  and  when  done  it  should  be  recorded, 
or  better  still  engraved  on  the  eyepiece  tube.  To  find  the 
"  constant "  of  an  eyepiece  with  a  given  tube  length,  first 
determine  the  combined  magnifying  power  of  that  eyepiece  on 
the  given  tube  length  with  any  objective,  say  one  of  medium 
power,  sudh  as  a  |-in.  or  J-in.  or  |%-in.  focus.     Secondly,  measure 


MAGNIFYING    POWER    OF    A    MICROSCOPE.  241 

the  exact  diameter  of  the  field  by  means  of  the  stage  micro- 
meter. The  product  of  these  two  quantities  is  the  constant  of 
that  eyepiece  with  the  given  tube  length. 

Example :  objective  §-in.,  eyepiece  compensating  x  8,  tube 
length  170  mm.,  measured  magnifying  power  280  diams.  : 
measured  field  0-023  in.  Product  is  6'44,  which  is  the  constant 
of  that  eyepiece  for  170-mm.  tube. 

The  power  of  any  other  objective  with  this  eyepiece  and  tube 
length  can  be  determined  by  merely  measuring  the  diameter  of  its 
field  by  the  stage  micrometer  ;  for  the  magnifying  power  will  ob- 
viously be  the  eyepiece  constant  divided  by  the  diameter  of  the  field. 

Thus,  the  problem  of  measuring  the  combined  magnifying 
power  is  brought  down  to  the  bed-rock  of  simplicity.  No  camera, 
no  regulation  of  illumination,  no  ten  inches  to  measure ;  in  brief, 
nothing  to  do  but  to  count  the  number  of  divisions  of  the  stage 
micrometer  in  a  diameter  of  the  field  and  then  divide  this  into 
the  eyepiece  constant. 

Example  1.     With  the  same    x8  compensating  eyepiece  and 

170-mm.    tube    a   |--in.    objective   gave   a    diameter  of   field    of 

6-44 
0*0165  in.     The  magnifying  power  therefore  is  rw  =  390. 

Example  2.     With  the  same  x  8  compensating  eyepiece  and 

1 70-mm.  tube  a  1  J-in.  objective  gave  a  diameter  of  field  of  0*185  in. 

„  6-44 

The  magnifying  power  therefore  is  ....  =  35. 

The  determination  of  the  constant  is  scarcely  any  more  trouble 

than  the  measurement  of  the  magnifying  power  of  one  objective, 

and  when  once  found  need  not  be  determined  again  ;  it  would 

ndeed  be  most  helpful  if    manufacturers  would   measure   these 

constants  and  engrave  them  upon  the  tubes  of  their  eyepieces. 

Obviously  the  diameter  of  the  field  can  be  measured  while  the 
microscope  work  in  hand  is  being  carried  on,  for  it  disturbs  neither 
the  microscope  nor  its  adjustments. 

This  method  has  been  tested  with  thirty- three  object  glasses, 
ranging  from  a  3-in.  to  a  yTrth  of  1'4  IS". A.,  by  fourteen  different 
makers,  and  with  various  eyepieces,  on  three  different  microscopes 
with  different  tube  lengths,  and  it  has  been  found  correct. 

My  best  thanks  are  due  to  Mr.  Grundy  for  his  kind  assistance  and 
notes.  Further  experience  has  shown  that  in  determining  the 
"  constant "   it  is  better  to   measure   the  magnifying  power   by 


242  E.    M.    NELSON    ON    A    NEW    METHOD    OF    MEASURING    THE 

direct  projection  on  to  a  scale,  without  the  intervention  of  any 
camera  lucida  or  drawing  instrument ;  the  position  of  the 
Ramsden's  disc,  from  which  the  10-in.  projection  distance  is 
measured,  is  easily  found  by  means  of  a  piece  of  ground  glass. 
An  excellent  scale  for  the  measurement  of  low  powers  is  a 
Lufkin  3-in.,  No.  2111,  price  Is. 

[Practical  members  ma}7,  by  this  time,  be  ready  to  ask,  "  What 
is  the  practical  use  of  this  system  ? '  As  a  general  answer  it 
might  be  said  that  it  shows  how  the  materials  for  an  important 
microscopical  measuring  tool  can  be  easily  determined. 

But  another  practical  reason  for  my  taking  interest  in  our 
veteran  member's  paper  is  the  hope  that  it  will  stimulate  some 
of  us  to  take  an  increased  interest  in  microscopical  measurements. 

I  hardly  need  to  impress  on  members  the  value  of  actually 
measuring  objects,  beyond  offering  a  reminder,  that  measurements 
are  the  fundamental  basis  of  microscopical  science,  and  of  every 
branch  of  science.  Some  would,  perhaps,  claim  to  put  mathe- 
matics in  this  honourable  position,  but  mathematics  would  be  in 
a  most  sorry  plight  without  measurements  in  various  forms. 

Mr.  Nelson,  in  a  letter,  says :  "  The  combined  magnifying 
power  is  wanted  for  drawings.  Beale's  method  of  exhibiting  a 
drawing  of  the  stage  micrometer  with  the  picture  is  quite  the 
best,  but  it  is  adopted  by  only  a  few  authors."  And  he  mentions 
an  instance  of  great  trouble  being  caused  by  some  drawings  in 
books  on  microscopical  subjects  having  the  magnifications  wrongly 
stated  in  the  legend. 

It  will  have  been  noticed  that  Mr.  Nelson  has,  hitherto,  con- 
fined the  use  of  the  "eyepiece  constant," for  one  eyepiece,  to  one 
definite  tube  length  for  one  constant ;  but  used  it  for  getting 
the  total  magnification  with  varying  powers  of  objectives. 

Tests  have,  however,  shown  that  the  total  magnification  can  be 
determined,  by  his  method,  for  different  tube  lengths  just  in  the 
same  way  as  for  different  powers  of  objectives.  Mr.  Nelson 
himself  says  that  "  increase  of  tube  length  increases  the  power 
and,  of  course,  diminishes  the  field,  and  is  just  the  same  as 
putting  a  higher-power  objective  on  the  nosepiece ;  the  constant 
of  the  eyepiece  remains  the  same."  In  support  of  this  statement, 
I  give  belowr  a  few  of  the  results  of  experiments  made  by  Mr. 
Nelson  not  many  days  ago. 


MAGNIFYING    POWER    OF    A    MICROSCOPE. 


243 


Tests  with  Powell  &  Lealand's  Low-angled  ^in.  Objective. 


Eyepiece. 

Tube  length. 

Diameter  of  field. 

Magnifying  power. 

Eyepiece  constant. 

No.  1 

12  in. 
♦5  ., 

0-036 
0-0675 

103 
56 

3-708 
3-7N 

No.  2 

12  in. 

6  „ 

0-031 
0-0615 

135 

7(> 

4-185 
4-305 

No.  4 

12  in. 

6  „ 

0-0267 
0-052 

267 
135 

7-129 
7-02 

Other  Tests  with  ^-in.  Objective. 


Eyepiece  constants. 

Eyepiece. 

Tube  length,  8*75  in. 

Tube  length,  6-7  in. 

A(E) 
Z  12  C 

W  1 
2 

K3 

613 

5-2 
3-69 
413 
5-64 

6-04 

51 

3-54 

4-10 

5-6 

Tube  length,  14*6  in. 

Tube  length,  5 -3  in. 

K3 

5-62 

5-64 

Magnifications         .         .     250 

94 

Notice  how  nearly  alike  the  eyepiece  constant  is  for  each  pair 
of  tests  when  different  tube  lengths  are  used,  but  the  same  eye- 
piece and  objective.  The  last  pair  are  practically  the  same, 
although  the  tube  lengths  vary  to  an  extraordinary  extent. 
Mr.  Nelson  says  that  "they  are  all  done  with  extreme  accuracy 
by  projection.  In  every  case  the  Ramsden's  disc  was  found  and 
the  screen  placed  ten  inches  from  it."  The  magnifications  were 
250  and  94  diameters. 

There  is  another  easy  way  in  which  the  information  given  by 
the  "  eyepiece  constant  "  may  be  used  for  determining  the  total 
magnification  for  any  tube  length.  Suppose,  for  example,  the 
eyepiece  constant  has  been  obtained  with  a  given  objective,  eye- 
piece, and  tube  length,  a  record  being  made ;  then  it  is  only 
necessary  to  work  a  very  simple  proportion  sum  to  determine — at 
any  time — the  total   approximate  magnification   with   any   tube 


244  E.  M.    NELSON    ON    MAGNIFYING    POWER    OF    A    MICROSCOPE 

length.     All    other  conditions  being  the  same,  the    total   mag- 
nification will  be  proportional  to  the  tube  lengths  used. 

Take  the  extraordinary  difference  of  tube  length  shown  by  the 
figures  given  below  : 

Tube  length.  Magnification. 

14-6  in.  250 

5-3  in.  94 

Then 

Magnifica- 
Magnification  with  long  tube  x  short  tube  length       250  x  5-3         tion  for 

short  tube 
length. 

Magnifica- 
tion for 

Snort  tube  length.  5#3         '  long  tube 

length. 

It  is  also  worth  mentioning  that  the  diameter  of  the  field  may 
be  measured  in  millimetres,  instead  of  inches,  if  millimetres  are 
used  when  determining  the  value  of  the  eyepiece  constant.  And 
members  will  probably  find  this  a  great  convenience. 

J.  Grundy.] 


Long  tube  length 

14-6 

And 

Magnification  with  short  tube  x  long  tube  length 

94  x  14-6 

Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII. ,  No.  73.  November  1913. 


245 


PROCEEDINGS 

OF    THE 

QUEKETT   MICROSCOPICAL   CLUB. 

At  the  meeting  of  the  Club  held  on  March  25th,  1913,  the 
President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair,  the 
minutes  of  the  meeting  held  on  February  25th  were  read  and 
confirmed. 

Messrs.  J.  T.  Cook,  David  Henry  Shuckard  and  W.  E. 
Ford-Fone  were  balloted  for  and  duly  elected  members  of  the 
Club. 

The  Hon.  Secretary  announced  that  Mr.  G.  T.  Harris,  of 
Sidmouth,  a  former  member  of  the  Club,  had  made  a  very 
handsome  donation  in  the  form  of  a  type  collection  of  Hydrozoa, 
numbering  72  preparations.  These  had  been  collected  on  the 
south-west  and  west  coasts  of  England,  and  should  prove 
very  useful  to  any  member  making  a  systematic  study  of  the 
group,  especially  as  the  slides  are  accompanied  by  a  resume  as 
a  help  in  diagnosing  the  more  difficult  species.  Mr.  Harris 
also  sent  a  paper  which  will  be  read  at  the  next  meeting,  on 
"The  Collection  and  Preservation  of  the  Hydrozoa." 

A  vote  of  thanks  to  Mr.  Harris  for  his  valuable  donation 
was  proposed  by  the  President,  and  carried  by  acclamation. 

Mr.  A.  A.  C.  Eliot  Merlin,  F.R  M.S.,  sent  for  exhibition  five 
photomicrographs,  taken  at  x  320,  of  diatoms  from  a  slide 
prepared  by  the  late  C.  Haughton  Gill  (see  Journal  R.M.S., 
1890,  p.  435).  They  were  of  Epithemia  turgida,  Stauroneis 
phoenice7ite?'07i,  Pinnularia  major,  under  surface  showing  per- 
forations on  ribbing  partly  filled  with  the  mercurous  sulphide, 
and  two  others. 

A  paper  by  Messrs.  Heron-Allen  and  Earland,  "On  some 
Foraminifera  from  the  Southern  Area  of  the  North  Sea,  dredged 
by  the  Fisheries  cruiser  '  Huxley ,'"  was  read  by  Mr.  Earland. 
Mr.  Earland  said  that  after  the  reading  of  the  paper  by  Mr. 
Heron-Allen  and  himself,  "  On  the  Occurrence  of  Saccammina 


246  PROCEEDINGS    OF    THE 

sphaerica  and  Psammosphaeria  fitsca,"  before  the  "  Challenger  " 
society  in  October  of  last  year,  Mr.  J.  0.  Borley,  of  the  Fisheries 
Department  of  the  Board  of  Agriculture,  suggested  that  it  would 
be  interesting  if  they  continued  their  investigations  in  the 
southern  area  of  the  North  Sea  with  a  view  to  determining  the 
distribution  of  the  two  species  in  that  area.  This,  after  some 
hesitation,  they  agreed  to  do ;  but  with  little  expectation  that 
any  observations  of  interest  would  result,  as  Mr.  Borley  had 
already  confirmed,  from  his  personal  experience,  the  generally 
held  opinion  that  Foraminifera  of  all  kinds  were  of  extremely 
rare  occurrence  in  these  waters.  The  shallowness  of  the  sea, 
and  consequent  disturbance  due  to  wave  and  tidal  action,  were 
considered  to  be  factors  limiting  the  possibilities  of  Khizopodal 
distribution.  Material  was  examined  from  six  stations  repre- 
senting two  widely  separated  areas  of  the  North  Sea,  three 
stations  being  far  to  the  north-east  of  the  Dogger  Bank  near  the 
Great  Fisher  Bank,  while  the  other  three  stations  were  in  the 
belt  of  deep  water  which  lies  to  the  west  of  the  Dogger,  close  in 
to  the  Northumberland  coast.  The  depths  ranged  between  31 
and  45  fathoms. 

A  number  of  photomicrographs  were  projected  upon  the  screen, 
and  briefly  described  by  Mr.  Earland.  Nubecidaria  lucifuga 
(Def ranee),  a  southern  form,  has  an  extended  range  as  far  as 
the  English  Channel.  It  is  common  at  Bognor  and  Selsey,  and 
a  few  specimens  had  been  found  near  the  Orkneys  and  in  Moray 
Firth.  Miliolina  seminulum  (Linne)  occurs  at  every  station  in 
both  areas.  It  is  the  dominant  miliolid  of  the  North  Sea,  and 
is  of  world-wide  distribution.  Of  the  two  species  especially 
searched  for  Psammosphaera  fusca  (Schulze)  was  found  to  occur 
at  all  stations  except  one  in  the  inshore  area.  Saccammina 
sphaerica  (Sars)  does  not  occur  in  any  of  the  outer,  or  Great 
Fisher  Bank,  collections,  but  does  occur  at  two  inshore  stations. 
The  specimens  found  were  extremely  small.  The  dominant 
arenaceous  form  was  Eeophax  scorpiurus  (Montfort).  The 
dominant  Textularian  was  Verneuilina  polystropha.  It  occurred 
in  great  numbers  and  variety  at  every  station.  The  genus 
Lagena  is  abundantly  represented  in  the  inshore  station  dredg- 
ings,  twenty-eight  species  being  recorded,  while  at  the  outer 
stations  only  eight  species  were  found.  Truncatidina  lobatula 
(W.  and  J.),  Nonionina  depressula  (W.  and  J.),  and  Polystomella 


QUEKETT    MICROSCOPICAL    CLUB.  247 

striato-punctata  (F.  and  M.)  occur  abundantly  everywhere,  and 
form  the  bulk  of  all  the  cleaned  material. 

The  President,  in  proposing  a  vote  of  thanks  for  the  paper, 
said  he  much  admired  the  photographs  shown,  which  were  the 
best  of  the  kind  he  had  seen.  He  would  like  to  ask  Mr.  Ear- 
land,  with  regard  to  the  criteria  of  specific  characters,  How 
could  one  tell  one  species  from  another,  seeing  that  there  is  so 
much  variation  within  the  same  species  ? 

The  vote  of  thanks  was  carried  unanimously. 

In  replying,  Mr.  Earland  said  he  had  to  thank  Mr.  A.  E. 
Smith  for  making  the  negatives,  and  Mr.  Lovegrove  for  the 
lantern  slides.  Regarding  specific  differences,  probably  Prof. 
Dendy  would  have  no  difficulty  in  identifying  sponges  which  he 
(Mr.  Earland)  would  not  be  able  to  tell  one  from  another. 
There  are  constant  points  always  present  which  make  it  more 
or  less  easy  to  diagnose  within  certain  limits.  As  regards  specific 
features  in  Foraminifera,  there  are  none  such  as  we  find  between, 
say,  a  cat  and  a  dog.  Probably  generic  differences  in  Fora- 
minifera are  about  equal  to  specific  differences  in  higher  forms. 

Mr.  D.  Bryce  gave  a  resume  of  a  paper  he  had  contributed 
on  "  Five  New  Species  of  Bdelloid  Rotifers."  Four  of  the  new 
species  belong  to  that  important  section  of  the  Philodiniclae  in 
which  the  food  is  formed  into  pellets  after  passing  through  the 
mastax,  and  are  assigned  to  the  genus  Habrotrocha.  The  new 
species  are  IT.  munda,  H.  torquata,  U.  spicida,  and  H.  ligula. 
The  fifth  species,  Callidina  Bilfingeri,  belongs  to  the  more 
numerous  section  of  the  same  family  in  which  the  food  is  not 
at  any  time  agglutinated  into  pellets,  and  being  oviparous,  and 
possessed  of  three  toes,  is  a  member  of  the  genus  Callidina,  as 
now  restricted. 

The  President  said  they  were  all  much  indebted  to  Mr.  Bryce 
for  bringing  these  interesting  details  before  them. 

A  vote  of  thanks  to  Mr.  Brvce  for  his  communication  was 
carried  unanimously. 


At  the  meeting  of  the  Club  held  on  April  22nd,  1913,  the 
Vice-President,  E.  J.  Spitta,  L.R.C.P.,  M.R.C.S.,  in  the  chair, 
the  minutes  of  the  meeting  held  on  March  25th  were  read  and 
confirmed. 


248  PROCEEDINGS    OF   THE 

Messrs.  F.  J.  Cheshire,  Henry  Edwards,  and  H.  D.  Rawson 
were  balloted  for  and  duly  elected  members  of  the  Club. 

The  List  of  Donations  to  the  Club  was  read  and  the  thanks  of 
the  members  voted  to  the  donors. 

Mr.  C.  D.  Soar,  F.R.M.S.,  read  a  note  describing  two  new 
species  of  water-mites.  These  were  Arrhenurus  Scourfeldi  sp. 
now  and  Acercus  longitarsus  sp.  nov..  The  first  was  taken  by 
Mr.  Scourfield  in  Cornwall,  in  fresh  water,  in  the  autumn  of 
1912.  It  belongs  to  the  sub-genus  Megalurus,  female  unknown. 
The  new  species  of  Acercus  is  named  from  the  unusually  long 
tarsi  found  in  the  fourth  pair  of  legs.  Locality,  South  .Devon- 
shire, female  unknown.  Mr.  Soar  also  said  that  Mr.  Williamson, 
F.R.S.E.,  in  working  out  the  material  on  the  genus  Sperchon 
had  found  two  species  new  to  Britain,  and  two  that  have  only 
been  recorded  for  Ireland.  These  were  Sperchon  clupeifer  Pier, 
sub-genus  Hispidosperchon,  from  Oban  and  Norfolk  Broads. 
Sperchon  tenuabllis  Koen,  sub-genus  Hispidosperchon,  from 
Oban.  Recorded  by  Halbertin  Clare  Island  Survey  for  Ireland. 
Sperchon  papillosus,  Sig.  Thor,  sub-genus  Squamosus,  Oban, 
recorded  by  Halbert  for  Ireland ;  and  Sperchon  Thienemanni, 
Koen,  sub-genus  Rugosa,  from  Derbyshire.  Drawings  of  the 
two  new  species  were  exhibited. 

The  Chairman  said  they  were  all  deeply  indebted  to  Mr.  Soar 
for  bringing  these  new  species  of  Hydrachnidae  before  them,  and 
they  would  be  able  to  appreciate  the  value  of  the  paper  more 
when  in  print.  The  drawings  in  illustration  of  the  species 
described  were  very  tine  indeed. 

The  thanks  of  the  meeting  were  unanimously  voted  to  Mr.  Soar 
for  his  paper. 

In  the  absence  of  the  author,  the  Hon.  Treasurer,  Mr.  F.  J. 
Perks,  read  a  paper  on  "  The  Collection  and  Preservation  of  the 
Hydroida,"  by  Mr.  G.  T.  Harris,  of  Sidmouth,  a  former  member 
of  the  Club.  The  author  said  that  the  Hydroida  are  too  well 
known  as  affording  both  beautiful  and  interesting  objects  to  need 
any  eulogy  at  his  hands.  Bearing  in  mind  that  this  paper  is 
written  more  for  the  help  of  the  novice  than  as  a  communication 
offering  original  matter,  the  writer  wished  to  safeguard  himself 
from  any  charge  of  carelessness  by  warning  the  uninitiated  that 
collecting,  say,  rotifers  and  collecting  hydroids  are  two  totally  and 
very  dissimilar  things. 


QUEKETT    MICROSCOPICAL    CLUB.  249 

A  hearty  vote  of  thanks  was  given  to  Mr.  Harris  for  his 
interesting  paper,  which  was  well  illustrated  by  about  twenty 
preparations  from  those  which  he  had  presented  to  the  Club  at 
the  March  meeting.  The  preparations  were  arranged,  mostly 
with  dark-ground  illumination,  under  microscopes  kindly  lent  by 
Messrs.  H.  F.  Angus  &  Co. 

The  Chairman,  in  moving  a  vote  of  thanks  to  Messrs.  Angus, 
which  was  carried  bv  acclamation,  said  that  in  London  members 
took  for  granted  that  there  was  never  any  difficulty  in  getting 
their  optician  friends  to  lend  the  Club  any  reasonable  number  of 
microscopes  ;  but,  as  he  had  found  by  recent  experience,  outside 
of  London  such  a  thing  was  practically  an  impossibility  ;  even  in  a 
large  town  the  number  of  microscopes  available  was  very  small. 
By  being  reminded  of  this  he  hoped  they  would  more  fully  appre- 
ciate their  good  fortune. 


At  the  meeting  of  the  Club  held  on  May  27th,  1913,  the 
President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair,  the 
minutes  of  the  meeting  held  on  May  22nd  were  read  and  con- 
firmed. 

Messrs.  Stanley  Hall  and  Reginald  Hook  were  balloted  for  and 
duly  elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks  of 
the  members  were  voted  to  the  donors. 

The  President  said  that  for  many  years  past  a  number  of 
pamphlets,  etc.,  had  been  received  by  the  Club,  which,  not  being 
considered  of  sufficient  value  to  bind,  had  bden  allowed  to 
accumulate  and  were  stored  in  a  room  downstairs.  These  had 
long  been  a  kind  of  white  elephant  to  the  Committee,  who  had  at 
length  decided  to  deal  with  them,  and  had  appointed  a  sub-com- 
mittee for  this  purpose.  These  gentlemen  had  gone  through 
them  and  had  come  to  the  conclusion  that  a  large  mass  of  this 
material  must  be  disposed  of,  and  the  question  arose  as  to  how 
this  was  to  be  done,  and  it  had  been  resolved  to  offer  the  bulk  to 
some  dealer  in  second-hand  books,  but  first  of  all  to  offer  them  to 
the  members  of  the  Club.  For  this  purpose,  lists  would  be  pre- 
pared and  laid  upon  the  table  at  the  next  Gossip  meeting  and 
again  at  the  next  Ordinary  meeting,  for  members  to  inspect  and 
to  make  offers  for  any  which  they  might  care  to  possess.     The 

Journ.  Q.  M.  C„  Series  II.— No.  73.  17 


260  PROCEEDINGS    OF   THE 

Librarian  was  empowered  to  receive  such  offers  for  them  and  to 
accept  those  which  he  deemed  satisfactory.  It  was  not  possible 
to  bring  them  up  for  inspection,  as  there  was  about  a  ton  and 
a  half  of  them. 

A  visitor,  Mr.  J.  Watson,  exhibited  multiple  images  formed  by 
the  cornea  of  the  eye  of  a  hive  bee  mounted  dry. 

Mr.  J.  Watson  said  the  slide  was  that  of  the  eye  of  a  honey 
bee  prepared  so  as  to  show  the  portrait  of  the  bee-keeper  in  every 
facet  just  as  the  bee  would  see  it.  He  had  been  told  it  could  be 
done  with  the  eye  of  a  beetle,  but  that  the  hairs  on  the  eye  of  the 
bee  made  it  a  difficult  matter  to  accomplish;  but  by  mounting  the 
object  in  the  way  he  described,  so  that  the  hairs  were  free  from 
pressure  on  the  under  side  of  the  slide,  he  had  succeeded  in 
obtaining  the  desired  result,  and  he  had  obtained  a  good  photo- 
graph of  it  with  half  an  hour's  exposure. 

The  President  said  that  at  a  Society  such  as  theirs  it  wras 
needless  to  explain  that  this  was  not  the  view  which  the  bee  got, 
as  no  doubt  in  some  way  it  saw  a  single  image,  but  he  just  men- 
tioned this  to  prevent  any  mistake,  as  he  thought  he  heard  it 
stated  that  this  was  how  the  bee  saw  the  bee-master.  Multiple 
images  such  as  were  shown  could  be  got  in  a  variety  of  ways,  and 
he  remembered  that  exactly  the  same  thing  was  done  at  one  of 
the  Royal  Society's  soirees  with  the  epidermic  cells  of  a  plant. 
They  were,  however,  much  obliged  to  Mr.  Watson  for  bringing 
and  explaining  his  exhibit. 

Mr.  E.  Inwards  had  found  that  a  small  knob  fitted  near  the 
hinge -joint  of  the  stop-carrier  of  substage  condensers  was  more 
convenient  in  working  than  having  to  feel  on  the  right  for  the 
usual  long  projecting  end,  which  is  very  often  in  close  proximity 
to  the  iris-handle. 

Mr.  T.  A.  O'Donohoe  read  a  paper  illustrated  by  a  number  of 
lantern  photographs,  at  various  degrees  of  magnification,  of  the 
"  Minute  Structure  of  Coscinodiscus  asteromjrfialus  and  of  the  two 
species  of  Plenrosigma,  P.  angulatium  and  P.  balticum.  Mr. 
O'Donohoe  then  showed  an  interesting  series  of  photographs,  at 
various  magnifications,  of  P.  balticum,  some  showing  fine,  hair- 
like,  bent  fibrils  breaking  away  from  the  valve.  Others  showed 
the  outer  membrane  breaking  up  into  fibrils,  and  sometimes 
isolated  dots. 

Mr.  W.  E.  Brown  said  that  the  fibrils  shown  by  Mr.  O'Donohoe 


QUEKETT    MICROSCOPICAL    CLUB.  251 

had  been  known  to  him  for  a  long  time,  but  lie  had  never 
regarded  them  as  structure,  but  rather  as  salt  which  had 
crystallised  out  after  mounting.  All  these  fibrils  consisted  of 
rows  of  dots  connected  by  bars,  and  there  always  seemed  to  him 
to  be  some  difference  between  these  and  the  general  structure. 

Mr.  E.  Pitt  exhibited  and  described  the  Cambridge,  Minot  and 
Spencer  microtomes,  and,  after  the  adjournment  of  the  meeting, 
gave  a  demonstration  of  ribbon  section-cutting. 

A  vote  of  thanks  was  accorded  Mr.  Pitt  for  his  exhibition. 


At  the  meeting  of  the  Club  held  on  June  24th,  1913,  the 
President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair,  the 
minutes  of  the  meeting  held  on  May  27th  were  read  and  con- 
firmed. 

Messrs.  Frank  Deed,  C.  Tierney,  D.  L.  Newmarch,  E.  L. 
Fen  wick,  and  H.  H.  Dean  were  balloted  for  and  duly  elected 
members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks 
of  the  members  voted  to  the  donors. 

The  Hon.  Secretary  read  a  note  from  Mr.  E.  M.  Nelson 
describing  Koristka's  new  loup.  The  writer  said  that  in  1885 
he  brought  to  the  notice  of  the  Club  the  then  new  Zeiss-Steinheil 
loups,  which  had  just  arrived  from  Jena.  These  lenses  have  been 
very  popular,  and  have  since  been  copied  by  every  maker,  both 
here  and  on  the  Continent. 

There  is  now  a  new  form  of  loup  with  which  the  Club  should  be 
acquainted;  it  is  the  achromatic  doublet  of  Koristka.  The  following 
are  the  measured  particulars  (not  taken  from  a  catalogue) : 

Doublet,  power  10,     field  1|  cm.,  working  distance  2  cm. 

Top  lens  alone,  ,,        5|,     ,,     2     „  „  ,,        4    „ 

Bottom  lens  alone,      ,,        3|,     „     4      ,,  „  ,,         5    „ 

The  defining  powrer  of  this  loup  is  excellent,  and  prolonged 
work  with  it  seems  easier  than  with  a  Steinheil ;  somehow  or 
other  work  with  a  Steinheil  is  tiring  to  the  eye.  The  price  of 
this  fine  lens,  in  a  wooden  box,  is  only  12s.,  but  although  the 
price  is  so  low,  the  quality  of  workmanship  is  particularly  high. 
Among  cheap  loups  we  so  often  find  that  the  lenses  are  im- 
perfectly polished,  the  threads  of  the  screws  badly  cut,  so  that 
they  do  not  engage   readily,  and  the  quality  of   materials  used 


252  PROCEEDINGS    OF    THE 

inferior.  But  this  new  loup  exhibits  none  of  these  defects,  and 
Koristka  is  to  be  congratulated  on  having  brought  out  at  a  low- 
figure  a  loup  which  compares  favourably  in  the  quality  of  its 
finish  with  the  most  expensive  grades  of  work  in  this  line.  This 
high  standard  of  workmanship  extends  also  to  Koristka's 
objectives,  eye-pieces  and  other  apparatus. 

Mr.  A.  A.  C.  Eliot  Merlin,  F.R.M.S.,  sent  a  note  on  "  Secondary 

Hairs  on  Foot  of  a  Ceylon  Spider."     The  main  hairs  on  the  foot 

of  a  very  large  species  of  Ceylon  spider,  the  name  of  which  is 

unknown,   have   proved  to   be  densely   covered  with  small  short 

spines  or  hairs  so  transparent  as  to  be  observable  with  difficulty 

even    by    means   of   an    oil-immersion    objective.     The  specimen 

examined   was  obtained    and   mounted    in    balsam    by   the  late 

Staniforth  Green,  who  was  for  many  years  resident  at  Colombo. 

When  the  main  hairs  are  viewed  with  a  dry  lens,  of  moderately 

large  aperture  they  plainly  exhibit  a  regular  clotted   structure, 

this  being  composed  of   the  ring  root  sockets  of  the   secondary 

spines,  which  are  themselves  so  transparent  in  the  balsam  mount 

as  to  require  great  aperture  to  define  properly.     It  is  suggested, 

however,  that  hairs  from  this,  or  similar,  large  species  of  spider 

might  be  mounted  in  glycerine  jelly  and  might  then  exhibit  the 

spines  more  easily.     The  preparation  in   which  the  spines  have 

been    noted    happens    to    be,    like    most    entomological    mounts 

intended  for  examination  under  low  or  medium  powers,  provided 

with  a  cover-glass  of  considerable  thickness,  while  the  foot  itself 

is   large    and    by   no    means    flat.       Under  these    conditions   an 

ordinary    oil-immersion    objective    could    not   be    employed,    but 

fortunately  a  Powell  one-twelfth  achromatic,  of  measured  N.A. 

1*27,  obtained  some  fifteen  years  ago,  possesses  quite  abnormal 

working  distance  compared  with  recent  productions  of  similar,  or 

slightly  greater,   aperture,    and  is  to  oil-immersion  lenses   what 

the  new  one-sixth  moderate  aperture  objectives  of  great  working 

distance  are  to  dry  systems.     The  lens  in  question  has  on  several 

occasions  proved   invaluable    for    the    examination    of    minute 

structure   in    ordinarily    mounted    entomological    specimens.      A 

photomicrograph  at  x  60  accompanied  the  paper  for  identification 

purpose,  and  was  exhibited. 

Mr.  Nelson  sent  for  exhibition  a  section  of  Green  Trap,  basic 
igneous  rock,  a  crystalline  aggregation  of  serpentine.  This,  he 
wrote,  might  easily  be  mistaken  for  a  piece  of  fossil  nummulite,  or 


QUEKETT    MICROSCOPICAL    CLUB.  253 

wood.      Xt  is  probable  that  the  fossil  known  as  Eozoon  cauadense, 
from  the  Laurentian  serpentine,  is  of  a  similar  nature. 

Mr.  H.  Sidebottom  contributed  a  valuable  paper  on  "The 
Lagenae  of  the  South- West  Pacific."  Mr.  A.  Earland,  F.R.M.S., 
in  introducing  this  paper,  said  it  was  a  very  lengthy  and  valuable 
one,  and  the  Club  would  be  proud  to  include  it  in  the  Journal. 
It  is  Part  2  of  a  paper  published  in  the  April  1912  issue  of 
the  Journal.  By  the  kindness  of  Mr.  H.  F.  Angus,  who  arranged 
an  exhibition  frame  for  the  drawings,  he  was  able  to  exhibit 
some  of  Mr.  Sidebottom  s  beautiful  drawings.  The  majority  of 
the  stations  from  which  the  specimens  dealt  with  were  derived 
(if  not  all)  lie  within  the  region  of  the  South  Pacific  known  to 
oceanographers  as  the  "  Aldrich  Deep."  This  area  lies  to  the 
east  of  New  Zealand,  between  15°  and  47°,  and  covers  about 
613,000  square  miles.  Three  soundings  exceeding  5,000 
fathoms  have  been  recorded  in  this  area  by  Commander  Balfour 
in  H.M.S.  "Penguin"  in  1895.  The  deepest  sounding  yet 
made,  however,  is  one  in  the  "Challenger"  Deep,  near  Guam, 
in  the  Ladrone  Islands.  This  is  5,269  fathoms,  nearly  six  miles. 
The  Aldrich  Deep  has  the  second  deepest  record,  5,155  fathoms. 
None  of  the  material  discussed  in  this  paper  comes  from  the 
deepest  parts  of  the  area.  The  depths  given  by  Mr.  Sidebottom 
range  between  328  fathoms  and  4,278  fathoms,  but  the  majority 
are  under  2,000  fathoms.  No  details  are  given  of  the  nature 
of  the  material  from  which  the  specimens  were  derived,  and 
possibly  the  information  was  not  in  the  author's  possession,  as 
the  majority,  at  any  rate,  of  the  specimens  had  been  picked  out 
by  Mr.  Thornhill  prior  to  his  death,  when  the  type  slides  passed 
into  the  hands  of  Mr.  Sidebottom  for  classification  and  description. 
It  may,  however,  be  fairly  surmised  that,  owing  to  the  distance 
of  the  area  from  any  land,  none  of  the  samples  would  be  terri- 
genous deposits,  but  would  be  true  oceanic  deposits.  Globigerina 
and  Pteropod  oozes  in  the  lesser  depths,  passing  into  pure 
Globigerina  ooze,  and,  beyond  the  2,000-fathom  line,  into  Red 
Clay.  The  presence  of  a  varied  and  rich  fauna  of  Lagenaa  in 
the  deep  water  of  the  South  Pacific  has  been  recorded  by  the 
"  Challenger"  Some  of  the  stations  of  that  ship  lie  within  the 
same  area  as  the  "  Penguin  "  material  worked  by  Mr.  Sidebottom, 
but  the  "  Challenger  "  material  was  either  very  poor  in  specimens 
compared   with   the    "Penguin"   or   it   was    very   incompletely 


254  PROCEEDINGS    OF    THE 

worked  out.  The  genus  Lagena,  while  of  world-wide  distribution 
and  occurring  at  all  depths,  presents  some  rather  curious 
anomalies  as  regards  its  occurrence  in  any  abundance.  It 
would  probably  be  almost  impossible  to  make  a  dredging  or  a 
shore  gathering  in  any  part  of  the  world  without  finding  the 
genus  represented  in  the  material.  But,  Mr.  Earland  said, 
from  practical  experience,  both  of  deep  and  shallow  water 
dredging  and  of  shore  collecting,  he  knew  that  in  one  sample 
the  genus  may  be  extremely  rare,  while  in  another  of  similar 
material  taken  a  few  miles  away,  under  similar  conditions  of 
depth,  the  genus  may  be  abundant  and  varied.  The  reason  for 
such  a  difference  is  obscure,  but  is  possibly  based  on  the  pro- 
portion of  mud  in  the  deposit.  Legena  as  a  genus  is  a  lover  of 
still  and  muddy  bottoms.  Globigerina  oozes  are,  as  a  general 
rule,  singularly  poor  in  Lagenae  :  hence  the  greater  wonder  at 
the  richness  of  the  fauna  in  these  "  Penguin "  oozes.  Mr. 
Sidebottorn  states  that  the  late  Mr.  Thornhill  had  picked  out 
over  12,000  specimens,  and  had  commenced  to  arrange  them  on 
a  scheme  which  he  had  devised  but  did  not  live  to  carry  out. 
Personally,  Mr.  Earland  said,  he  regretted  that  Mr.  Sidebottom 
had  not  found  time  or  opportunity  to  use  the  unique  material 
which  came  into  his  possession  at  Mr.  Thornhill's  death,  as  a 
centre  around  which  to  build  up  a  complete  monograph  of  this 
beautiful  genus.  Perhaps  he  may  yet  find  himself  able  to  deal 
with  this  task.  But,  in  any  case,  it  is  a  matter  for  congratula- 
tion that  Mr.  Thornhill's  work  did  not  perish  and  disappear 
unrecognised  on  his  death,  as  so  often  happens  when  a  worker 
dies,  but  that  his  material  has  fallen  into  the  hands  of  Mr. 
Sidebottom,  whose  beautiful  drawings  will  make  it  accessible  to 
all  interested  in  the  group. 

One  of  the  most  noticeable  features  of  this  group  is  the  very 
large  proportion  of  decorated  forms.  Many  of  the  recognised 
species  are  very  hard  to  identify  on  account  of  the  almost  in- 
finite variety  and  variation  of  the  minute  spines  and  markings 
which  characterise  them.  The  object  of  such  markings  seems 
to  be  quite  beyond  speculation.  They  are  quite  invisible  to  the 
naked  eye,  and,  unlike  the  markings  of  diatoms,  do  not  appear 
to  have  any  physiological  significance.  Mr.  Earland  thought 
the  Club  was  to  be  congratulated  on  obtaining  two  such  notable 
papers  for  publication  in  its  Journal, 


QUEKETT    MICROSCOPICAL    CLUB.  255 

The  President  said  that  he  was  afraid  he  was  not  able  to 
throw  any  light  on  the  significance  of  the  markings  and  char- 
acters of  the  kind  Mr.  Earland  had  mentioned.  He  thought 
they  were  quite  inexplicable  at  present.  It  must  be  admitted 
that  a  great  number  of  specific  characters  are  not  due  to  adapta- 
tions, and  one  may  go  further  and  ask  how  far  the  origin  of 
species  is  affected  by  natural  selection.  What  proportion  of 
specific  characters  are  adaptations  at  all  ?  How  often  can  one 
say  that  any  character  is  really  adaptive  ?  He  would  like  the 
opinion  of  some  of  the  Club  workers.  Would  Mr.  Rousselet, 
for  instance,  say  that  all  the  specific  characters  of  rotifers  were 
adaptations  ?  He  would  not  say  an  organism  wras  not  adapted 
to  its  environment,  but  he  would  say  that  many  organisms 
exhibit  a  whole  host  of  characters  not  due  to  environment. 
They  could  not  explain  everything  as  due  to  natural  selection. 
Darwin  laid  great  stress  on  "  The  Origin  of  Species  by  Means 
of  Natural  Selection,"  and  thought  that  specific  characters  came 
first,  and  then  natural  selection  came  in  and  weeded  out  any 
not  suited  to  the  environment. 

Mr.  C.  F.  Rousselet  thought  it  was  impossible  to  determine 
what  characters  were  really  adaptive  in  the  Rotifera. 

Mr.  D.  Bryce  said  natural  selection  did  not  apply  to  his 
Bdelloids,  as  they  were  all  females.  It  was  a  real  case  of  sur- 
vival of  the  fittest.  Occasionally  a  specific  character  must  be 
an  absolute  hindrance,  and,  in  the  case  of  long  spines,  must 
sometimes  be  positively  dangerous. 

The  President  said  it  was  very  difficult  to  put  oneself  in  the 
position  of,  for  instance,  a  sponge.  But  take  the  case,  say,  of  a 
small  protuberance  on  a  spicule,  which  spicule  is  quite  sur- 
rounded and  embedded  in  the  general  protoplasmic  mass  of  the 
animal,  and  then  assume  another  similar  spicule  which  is  without 
such  protuberance.  It  is  not  possible  to  conceive  that  either 
the  presence  or  absence  of  such  a  minute  speck  of  silica  could 
be  of  any  use  to  the  individual,  and  yet  such  a  difference  is  often 
absolutely  characteristic  of  a  species.  We  have  had  instanced 
this  evening  elaborate  decoration  and  markings  on  Foraminifera. 
These  animals  certainly  cannot  appreciate  them  visually,  as  they 
have  no  organs  of  vision  ;  and,  again,  in  life  the  markings  would 
be  concealed  under  the  usual  gelatinous  mass  of  exterior  proto- 
plasm.    The  markings  are  so  minute  that  it  is  quite  impossible 


256  Proceedings  of  the 

that  the  organisms  could  be  cognisant  of  their  existence  in  any 
way.  The  markings  are  of  such  a  nature  as  to  be  quite  without 
use  to  the  organism,  and  we  may  take  it  that  the  possession  of 
one  particular  pattern  is  of  just  as  much,  or  little,  use  to  the 
organism  as  the  possession  of  any  other  pattern.  Have  we  any 
right  to  say  that  any  one  of  the  patterns  is  an  adaptation  ? 

Mr.  A.  E.  Hilton  cited  the  case  of  the  Mycetozoa,  where  the 
specific  nomenclature  is  based  on  minute  markings  on  the  capil- 
litium.  These  markings  are  really  the  waste  products  of  the 
protoplasm  which  is  purifying  itself  in  spore-formation.  It  is 
quite  certain  that  the  cause  of  the  different  markings  must  be 
in  the  protoplasm  itself.  The  protoplasm  of  different  species 
makes  deposits  in  different  shapes,  and  these  must  be  largely 
dependent  on  the  condition  of  the  air,  as  regards  temperature 
and  moisture,  at  the  times  of  spore-formation.  The  real  seat 
of  the  difference  lies  in  the  protoplasm  itself. 

Mr.  W.  It.  Traviss  exhibited  and  described  a  simple  apparatus, 
for  use  in  pond-hunting,  for  collecting  water  from  depths  which 
cannot  be  reached  with  the  usual  dipping-tube  and  stick.  It 
consisted  of  a  light  metal  cylinder  closed  at  one  end.  At  the 
other  a  light  frame  is  fixed  in  a  sort  of  handle-shape.  This 
frame  serves  as  support  to  a  stout  metal  rod,  which  is  fastened 
at  the  other  end  centrally  to  the  bottom  of  the  cylinder.  On 
the  rod  slides  loosely,  first,  an  easily  fitting  cap  to  the  cylinder, 
and,  next,  several  lead  discs.  A  string  is  attached  to  the  bottom 
of  the  cylinder — actually  to  an  eye  formed  by  bending  the  end 
of  the  central  rod  which  is  projecting  outside.  Another  string 
is  attached  to  the  opposite  end  of  the  rod.  In  use  the  weight 
of  the  lead  discs  is  so  adjusted  that  they  will  take  the  cylinder 
down  to  the  bottom,  upside  down  and  full  of  air,  the  contrivance 
being  lowered  by  the  string  attached  to  the  bottom,  the  other 
string  hanging  slack.  On  reaching  the  bottom,  or,  if  desired, 
some  particular  depth  which  could  be  marked  on  the  string,  the 
second  string  is  gently  pulled,  bringing  the  mouth  of  the  cylinder 
away  from  the  bottom,  and  permitting  some  of  the  contained 
air  to  escape.  Two  or  three  tugs  at  the  string  will  allow  all  the 
air  to  rush  out,  and  at  the  same  time  fill  the  cylinder  with 
bottom-water.  It  will  now  be  right  side  up,  and  the  lead  weights 
which  carried  it  down  will  keep  the  loosely  fitting  lid  in  position 
as  the  apparatus  is  drawn  up  by  the  top  string.     Practically  no 


QUEKETT    MICROSCOPICAL    CLUB.  257 

exchange  of  water  takes  place.     Mr.  Traviss  also  exhibited   a 
very  convenient  and  portable  form  of  siphon-strainer. 

Several  members  testified  as  to  the  efficiency  of  Mr.  Traviss's 
apparatus,  which  he  used  at  the  last  excursion  of  the  Club 
(June  21st). 

A  paper  "  On  a  New  Method  of  Measuring  the  Magnifying- 
power  of  a  Microscope,"  communicated  by  Mr.  E.  M.  Nelson, 
F.R.M.S.,  was  read  by  Mr.  J.  Grundy. 

After  reading  Mr.  Nelson's  paper,  Mr,  Grundy  offered  a  few 
remarks  of  his  own. 

Mr.  Grundy  exhibited  a  modification  of  the  photomicrographic 
camera  projection  method.  A  light  cardboard  tube  of  about 
24  in.  diameter  and  about  12  in.  in  length  fits  loosely  over  the 
eye-piece  ;  the  other  end  is  supported  by  a  clamp-stand.  (The 
microscope  may  be  in  any  position;  inclined  is  most  convenient.) 
At  a  distance  of  about  10  in.  from  the  lower  end  a  circle  of  fine 
ground-glass  is  fitted.  This  is  carried  in  a  "  draw-tube,"  per- 
mitting correction  for  the  position  of  the  Ramsden  disc  for 
various  eye-pieces  or  for  different  tube-lengths.  If  a  micrometer 
is  placed  on  the  stage  the  projected  image  may  be  observed  on 
the  ground-glass,  and  the  divisions  gauged  with  dividers,  and 
compared  directly  with  an  ordinary  rule.  Mr.  Grundy  also 
exhibited  microscopes  fitted  with  Beale's  neutral-tint  camera- 
lucida,  Ashe's  modification  of  Beale's  form,  and  a  Wollaston 
model. 

The  President  said  they  were  much  indebted  to  Mr.  Nelson 
for  his  paper,  and  to  Mr.  Grundy  for  reading  it.  He  had  himself 
very  often  to  make  microscopical  measurements,  and  though  no 
doubt  the  method  described  was  very  good  in  theory  he  did  not 
know  how  it  would  work  out  in  practice  as  compared  with  the 
very  simple  method  which  he  was  accustomed  to  adopt — namely, 
by  drawing  the  object  with  a  Beale's  camera,  and  then  in  the 
same  way  drawing  the  micrometer  scale  when  placed  on  the 
stage  in  place  of  the  object.  By  applying  these  to  one  another 
he  could  measure  a  thing  in  a  very  short  time,  and  did  not  see 
how  he  could  possibly  go  wrong  in  so  doing,  although  there  might 
be  a  slight  distortion  caused  by  the  eye-piece. 

A  cordial  vote  of  thanks  was  accorded  to  Mr.  Nelson  for  his 
useful  paper,  and  to  Mr.  Grundy  for  the  interesting  way  in 
which  he  had  brought  the  paper  before  the  Club. 

Journ.  Q.  M.  G,  Series  II.— No.  73.  18 


258 


OBITUARY   NOTICE. 

THE   RIGHT   HON.   SIR    FORD   NORTH, 
P.C.,    F.R.S.,    F.R.M.S. 

Bom  January  \§th,   1830;    died  October  12th,   1913. 

We  regret  to  record  the  death  of  Sir  Ford  North,  one  of  our  well- 
known  members.  He  died  at  his  estate  in  Morayshire,  in  his  eighty- 
fourth  year.  He  was  the  son  of  a  solicitor,  and  became  a  barrister 
practising  in  the  Chancery  Courts  (1856).  He  was  made  a  Q.C. 
in  1877,  and  afterwards  a  judge,  at  first  in  the  Queen's  Bench 
division  (1881),  and  then  in  the  Court  of  Chancery  (1883),  He 
was  a  Fellow7  of  the  Royal  Society,  and  a  well-known  entomologist. 
He  was  elected  a  member  of  the  Q.M.C.  in  June  1894,  and  in  the 
same  year  F.R.M.S. ;  hewasamember  of  our  Committee  in  February 
1899,  and  was  one  of  our  Vice-Presidents  from  February  1901. 
His  unassuming  and  cordial  manner  and  the  interest  he  displayed 
in  the  objects  exhibited  by  members  produced  a  feeling  of  friend- 
ship towards  him  in  all  those  who  had  the  pleasure  of  meeting 
him,  while  his  patience  and  experience  in  directing  a  meeting 
when  he  occupied  the  chair,  as  was  frequently  the  case,  made  him 
a  most  valuable  member  of  the  Club,  and  one  whose  loss  we  all 
greatly  regret. 


259 


THE    PRESIDENT'S    ADDRESS. 

ORGANISMS    AND     ORIGINS. 

By  Prof.  Arthur  Dendy,  D.Sc.,  F.R.S. 

(Delivered  February  2ith,  1914.) 

I  have  in  my  library  a  copy  of  a  posthumous  edition, 
published  in  1732,  of  a  remarkable  work  by  John  Ray,  entitled 
"  Three  Physico-Theological  Discourses,  concerning  I.  The  Primi- 
tive Chaos,  and  Creation  of  the  World.  II.  The  General  Deluge, 
its  Causes  and  Effects.  III.  The  Dissolution  of  the  World,  and 
Future  Conflagration."  The  second  of  these  discourses  contains  a 
very  long  discussion  on  the  origin  of  fossils,  which  begins  as 
follows  :  "  Another  supposed  Effect  of  the  Flood,  was  a  bringing 
up  out  of  the  Sea,  and  scattering  all  the  Earth  over,  an  innumer- 
able Multitude  of  Shells  and  Shell-Fish ;  there  being  of  these 
Shell-like  Bodies,  not  only  on  lower  Grounds  and  Hillocks,  but 
upon  the  highest  Mountains,  the  Apennine  and  Alps  themselves. 
A  supposed  Effect,  I  say,  because  it  is  not  yet  agreed  among  the 
Learned,  whether  these  Bodies,  formerly  called  petrified  Shells,  but 
now-a-days  passing  by  the  Name  of  formed  Stones,  be  original 
Productions  of  Nature,  formed  in  imitation  of  the  Shells  of 
Fishes ;  or  the  real  Shells  themselves,  either  remaining  still 
entire  and  uncorrupt,  or  petrified  and  turned  into  Stone,  or,  at 
least,  Stones  cast  in  some  Animal  Mold.  Both  Parts  have  strong 
Arguments  and  Patrons.  I  shall  not  balance  Authorities,  but 
only  consider  and  weigh  Arguments." 

In  the  end  Ray  pronounces  in  favour  of  the  view  that  the 
fossils  are  real  shells  and  not  mere  sports  of  nature,  but  he  adopts 
a  most  singular  hypothesis  as  to  how  they  found  their  way  into 
their  present  situations.  It  is  only  fair  to  add  that  this  hypothesis 
did  not  originate  with  him,  but  was  the  offspring  of  the  fertile 
brain  of  his  "  learned  and  ingenious  Friend,  Mr.  Edward  Lhwyd."* 

*  1  am  indebted  to  rny  friend,  Mr.  A.  W.  Sheppard,  the  Editor  of  this 
Journal,  for  the  information  that  Mr.  Edward  Lhwyd,  M.A.,  F.R.S. ,  was 
keeper  of  the  Ashmolean  Museum  from  1690  to  1709,  and  published  a 
catalogue  of  fossils  in  1699. 

Journ.  Q.  M.  C  ,  Series  II.— No   74.  19 


260  the  president's  address. 

Mr.  Lhwyd  appears  to  have  been  much  impressed  by  the 
alleged  fact  that  marine  shells  are  sometimes  generated  in  the 
bodies  of  men  and  other  animals,  though  at  the  present  day  it  is 
difficult  enough  to  understand  how  such  statements  could  ever 
have  gained  credence.  He  observes  :  "  For  to  me  it  appears  a  far 
less  Wonder,  that  Shells  and  other  Marine  Bodies  should  be  pro- 
duc'd  in  the  Bowels  of  the  Earth,  than  their  Production  in  the 
Bodies  of  Men  or  Animals  at  Land,  And  that  they  have  been 
so  found,  is  sufficiently  attested,  both  by  Ancient  and  Modern 
Authors,  of  a  Credit  and  Character  beyond  all  Exception." 
Obviously  the  universal  deluge  could  hardly  be  held  responsible 
for  the  occurrence  of  marine  shells  in  human  bodies,  and  there- 
fore why  hold  it  responsible  for  the  occurrence  of  similar  things 
in  the  bowels  of  the  earth  % 

The  ingenious  Mr.  Lhwyd  proceeds  as  follows :  "  I  therefore 
humbly  offer  to  your  Consideration,  some  Conjectures  I  have  of 
late  Years  entertain'd  concerning  the  Causes,  Origine,  and  Use 
of  these  surprising  Phenomena.  I  have,  in  short,  imagin'd  they 
might  be  partly  owing  to  Fish  Spawn  received  into  the  Chinks 
and  other  Meatus' s  of  the  Earth  in  the  Water  of  the  Deluge,  and 
so  be  deriv'd  (as  the  Water  could  make  way)  amongst  the 
Shelves  or  Layers  of  Stone,  Earth,  &c.  and  have  farther  thought 
it  worth  our  Enquiry,  whether  the  Exhalations  which  are  raised 
out  of  the  Sea,  and  falling  down  in  Rains,  Fogs,  &c.  do  water 
the  Earth  to  the  Depth  here  required,  may  not  from  the 
Seminium,  or  Spawn  of  Marine  Animals,  be  so  far  impregnated 
with,  as  to  the  naked  E}^e  invisible,  animalcida,  (and  also  witli 
separate  or  distinct  Parts  of  them)  as  to  produce  these  Marine 
Bodies,  which  have  so  much  excited  our  Admiration,  and  indeed 
baffled  our  Reasoning,  throughout  the  Globe  of  the  Earth.  I 
imagin'd  farther,  that  the  like  Origine  might  be  ascribe!  to  the 
Mineral  Leaves  and  Branches,  seeing  we  find  that  they  are  for 
the  most  part  the  Leaves  of  Ferns,  and  other  Capillaries ;  and  of 
Mosses  and  such  like  Plants,  as  are  called  less  perfect ;  whose 
Seeds  may  be  easily  allow'd  to  be  wash'd  down  by  the  Rain  into 
the  Depth  here  required." 

You  will  note  that  the  Deluge  has  not  completely  disappeared 
from  the  hypothesis  after  all,  but  we  may  gather  from  what  follows 
that  it  has  crept  in  rather  by  force  of  habit,  and  that  the  author 
really  relies  principally  upon  the  clouds  and  rain  for  conveying 


THE    PRESIDENT'S    ADDRESS.  261 

the  "  Seininium "  into  the  crevices  of  the  rocks  where  it  is 
supposed  to  develop.  Indeed,  he  accounts  in  this  manner  for  the 
fact  that  so  many  of  the  fossil  shells  found  in  Great  Britain 
belong  to  species  not  found  in  the  adjacent  seas.  The  "  Seininium" 
has  been  brought  from  distant  regions  in  the  rain-clouds. 

In  order  to  make  his  argument  more  convincing,  Mr.  Lhwyd, 
who  is  quite  aware  of  some  of  its  weakest  paints,  adopts  the 
well-known  method  of  answering  possible  critics  in  advance. 
"  First"  he  says,  "It  will  be  questioned  whether  the  supposed 
Seminium  can  penetrate  the  Pores  of  Stones."  To  this  he  replies 
"  That  it's  manifest  from  Experience,  upon  which  all  solid 
Philosophy  must  be  grounded,  that  the  Spawn  of  Animals  may 
insinuate  itself  into  the  Mass  of  Stone.  And  this  plainly  appears 
from  Live  Toads,  found  sometimes  in  the  middle  of  Stones  at 
Land,  and  those  Shell-fish  called  Pholacles  at  Sea."  In  other 
words,  facts  are  facts,  and  there  is  no  getting  away  from 
them.  " Secondly,  'It  will  scarce  seem  credible'  that  such  Bodies, 
having  no  life,  should  grow,  especia'ly  when  confined  in  so 
seemingly  unnatural  a  Place  as  the  Earth,  &c."  The  answer 
to  this  is  again  supplied  by  the  voice  of  authority,  supplemented 
by  an  original  observation  on  the  part  of  the  author  which  in- 
dicates clearly  enough  the  amount  of  reliance  that  is  to  be  placed 
upon  his  conclusions.  "  That's  not  so  great  a  Wonder,"  he  says, 
"  as  that  Shells  should  be  sometimes  generated,  and  even  grow, 
tho'  they  contain  no  Animals,  within  humane  Bodies ;  and  within 
the  Mass  of  those  thick  Shells  of  our  large  Tenby  Oysters, 
which  I  formerly  mentioned  to  you,  as  first  shown  me  by  Mr. 
William  Cole  of  Bristol,  and  have  since  observ'd  myself.  For 
we  must  grant,  that  the  Earth,  even  in  any  Part  of  the  Inland 
Country,  is  much  fitter  for  their  Reception  and  Augmentation 
than  humane  Bodies ;  especially,  if  we  reflect,  that  when  the 
Spat  or  Seminium  here  suppos'd  meets  with  saline  Moisture 
in  the  earth,  living  Animals  are  sometimes  produced,  as  is  before 
attested."     And  so  on  to  ninthly  and  lastly. 

Evidently,  in  the  year  1698,  when  this  was  written,  the 
problem  of  how  the  apple  got  into  the  dumpling  had  not 
yet  been  solved  by  the  philosophers.  It  is  a  little  surprising, 
however,  that  such  views  should  have  been  accepted  by  so 
experienced  an  observer  as  John  Bay,  who  has  been  called 
the    Father    of    modern    zoological    science.      Nevertheless,    he 


262  the  president's  address. 

quotes  them  at  length,  and  adds  :  "  For  my  part  (if  my  Opinion 
be  considerable)  I  think  that  my  learned  Friend  hath  sufficiently 
proved  that  these  Fossil-shells  were  not  brought  in  by  the 
universal  Deluge.  He  hath  made  it  also  highly  probable,  that 
they  might  be  originally  formed  in  the  Places  where  they  are 
now  found  by  a  spermatick  Principle,  in  like  manner  as  he 
supposes.  Why  do  I  say  probable  ?  It  is  necessary  that  at  least 
those,  which  are  found  in  the  Viscera  and  Glands  of  Animals,  be 
thus  formed  ;  and  if  these,  why  not  those  found  in  the  Earth  ? 
I  shall  say  no  more,  but  that  those  who  are  not  satisfied  with 
his  Proofs,  I  wish  they  would  but  answer  them."  Thus  even 
Kay,  who  was  turned  out  of  his  Fellowship  at  Cambridge  because 
he  refused  to  make  a  declaration  with  regard  to  the  Solemn 
League  and  Covenant  demanded  by  the  authorities,  allowed 
himself  to  be  completely  enslaved  by  his  own  credulity  with 
regard  to  unverified  and,  indeed,  absurd  statements  as  to  the 
occurrence  of  marine  shells  in  the  bodies  of  land  animals  ! 

I  suppose  that  Mr.  Lhwyd's  quaint  hypothesis  was  almost  the 
last  of  the  many  curious  attempts  that  were  made  to  explain 
the  existence  of  fossils  before  our  modern  views  on  the  subject 
came  to  be  generally  accepted.  It  affords  an  interesting  illustra- 
tion of  the  power  of  uncriticised  authority  to  lead  people  astray. 
Unfortunately,  however,  we  cannot  do  without  authority  in  science. 
No  man  has  either  time  or  opportunity  to  prove  all  things  for 
himself.  Progress  is  rendered  possible  only  by  the  accumulation 
of  the  labours  of  many  workers,  each  relying  upon  his  fellows. 
The  only  safeguard  against  error  is  the  free  exercise  of  our 
critical  faculty  and  the  due  restraint  of  our  natural  credulity — 
the  original  sin  of  the  scientific  man. 

Let  us  turn  now  to  another  hypothesis.  In  1875  Prof.  Huxley, 
in  one  of  his  extraordinarily  stimulating  essays,*  discussed  the 
relation  which  exists  between  the  composition  of  the  earth's 
crust  and  the  organisms  by  which  it  has  been  populated.  He 
points  out  that  the  great  Swedish  naturalist  Linmeus,  who  was 
born  in  1707,  only  two  years  after  the  death  of  Kay,  had  already 
enunciated  the  dictum  that  "fossils  are  not  the  children,  but  the 
parents  of  the  rocks  " — in  other  words,  that  rocks  originate  from 

*  "On  Some  of  the  Results  of  the  Expedition  cf  H.M.S.  Challenger" 

1875].     Collected  Essays,  vol.  viii. 


THE    PRESIDENT'S    ADDRESS.  263 

animals  and  not  animals  from  rocks  ("  sic  lapides  ab  animalibus, 
nee  vice  versa  "). 

.After  discussing  the  character  of  the  various  deposits  which 
form  the  floor  of  the  ocean,  Prof.  Huxley  remarks :  "  If  the 
Challenger  hypothesis,  that  the  red  clay  is  the  residue  left  by 
dissolved  Foraminiferous  skeletons,  is  correct,  then  all  these 
deposits  alike  would  be  directly,  or  indirectly,  the  product  of 
living  organisms.  But  just  as  a  siliceous  deposit  may  be 
metamorphosed  into  opal  or  quartzite,  and  chalk  into  marble, 
so  known  metamorphic  agencies  may  metamorphose  clay  into 
schist,  clay-slate,  slate,  gneiss,  or  even  granite.  And  thus, 
by  the  agency  of  the  lowest  and  simplest  of  organisms,  our 
imaginary  globe  might  be  covered  with  strata,  of  all  the  chief 
kinds  of  rock  of  which  the  known  crust  of  the  earth  is  composed, 
of  indefinite  thickness  and  extent.   .   .   . 

"  Accepting  it  provisionally,  we  arrive  at  the  remarkable  result 
that  all  the  chief  known  constituents  of  the  crust  of  the  earth 
may  have  formed  part  of  living  bodies ;  that  they  may  be  the 
;  ash'  of  protoplasm/' 

The  view  that  the  red  clay  which  forms  the  floor  of  the  ocean 
at  very  great  depths,  and  extends  over  an  area  of  about  fifty 
million  square  miles,  is  derived  from  the  decay  of  the  skeletons 
of  Foraminifera  from  which  the  lime  has  been  dissolved  out, 
has  not  been  substantiated  by  later  investigations.  According 
to  Sir  John  Murray,  the  greatest  authority  on  the  subject, 
it  has  been  formed  chiefly  by  the  disintegration  of  pumice  and 
other  volcanic  ejecta. 

It  thus  appears  that  the  "  ash  of  protoplasm  ''  does  not  play 
nearly  such  an  important  part  in  the  formation  of  the  earth's 
crust  as  that  suggested  conditionally  by  Huxley. 

My  indefatigable  friend,  Mr.  Kirkpatrick,  however,  has  for 
some  time  been  raking  in  all  sorts  of  ashes  for  evidence  of  their 
origin,  and  has  come  to  the  conclusion  that  even  in  the  most 
unlikely  situations  traces  of  simple  organisms  may  still  be 
found.*  He  has,  I  fear,  as  yet  met  with  but  little  success  in 
convincing  his  scientific  colleagues  of  the  correctness  of  his 
observations,  but  his  results  are  certainly  in  close  agreement 
with  the  conclusions  arrived  at  by  Linnaeus  and,  provisionally, 
by  Huxley.  If  these  conclusions  were  correct  we  should  have 
-*  Vide  The  Niimmulosphere,  by  K.  Kirkpatrick.     London,  1913. 


264  the  president's  address. 

to  conceive  of  the  solid  crust  of  the  earth  as  the  result  of  a 
constant  interchange  of  matter  between  the  living  and  the 
dead,  accompanied  by  physical  and  chemical  processes  of  endless 
complexity.  We  might  even  think  of  it  as  a  huge  composite 
organism,  alive  only  at  the  surface,  but  built  up  on  the  waste 
products  of  its  own  collective  metabolism,  like  a  world-embracing 
coral  reef.  I  fear,  however,  that  such  a  conception  would  be 
more  picturesque  than  accurate. 

Even  if  we  accepted  such  a  hypothesis  we  should,  of  course, 
have  to  remember  that  such  a  state  of  affairs  could  only  have 
arisen  through  a  slow  and  gradual  process  of  evolution. 
Whether  this  process  occupied  a  hundred  million  or  a  thousand 
million  years  would  be  a  matter  of  comparatively  small  import- 
ance. It  would  be  enough  for  our  present  purposes  to  recognise 
that  it  must  have  had  a  beginning  at  some  extremely  remote 
period  of  geological  time,  when  the  crust  of  the  earth  could  not 
by  any  possibility  have  been  composed  of  the  detritus  of  living 
things. 

It  is  generally  admitted  that  there  are  only  two  possibilities 
with  regard  to  the  origin  of  terrestrial  organisms.  Either  thev 
must  have  been  imported  from  some  other  planet  in  the  form 
of  germs,  or  they  must  have  developed  on  the  earth's  surface 
from  inorganic  materials  that  formed  part  of  the  earth  itself. 
Either  event  could  only  have  taken  place  after  the  earth  had 
cooled  sufficiently  to  permit  of  the  existence  of  those  peculiarly 
unstable  colloidal  compounds  of  which  living  bodies  are  composed. 

The  first  hypothesis  has,  as  you  are  aware,  received  the  sup- 
port of  no  less  eminent  a  man  of  science  than  the  late  Lord  Kelvin, 
who  believed  it  possible  that  the  germs  of  living  organisms 
might  have  been  brought  to  the  earth  by  meteorites.  The  chief 
objection  to  this  view  appears  to  be  the  difficulty  of  believing 
that  any  organism  could  withstand  the  heat  generated  by  the 
friction  of  the  meteorite  with  the  earth's  atmosphere. 

A  modification  of  the  same  hypothesis,  sometimes  known  as 
the  Theory  of  Panspermia,  is  maintained  by  Svante  Arrhenius 
and  others.  According  to  this  theory,  numerous  living  germs  of 
extremely  minute  size  occur  scattered  through  space,  derived 
from  various  planets  upon  which  life  is  supposed  to  exist, 
though  at  present  we  have  no  proof  whatever  that  life  does 
exist    upon   any   pi  met   except  the  earth  itself.     The  nature  of 


THE    PRESIDENT'S    ADDRESS.  265 

these  invisible  germs  is  enigmatical  in  the  highest  degree.  They 
are  supposed  to  be  propelled  through  space  by  the  pressure  of 
the  radiant  energy  streaming  from  the  sun — and  it  has  indeed 
been  demonstrated  that  very  minute  particles  can  be  propelled  in 
this  way  by  rays  of  light.  It  has  been  objected  to  this  view 
that  no  organisms  could  withstand  the  intense  cold  of  inter- 
planetary space,  but  we  know  that  living  organisms  withstand 
low  temperatures  much  better  than  they  withstand  high  ones, 
and  there  appears  to  be  no  known  minimum  at  which  all  life 
is  necessarily  destroyed.  A  more  serious  objection  is  to  be  found 
in  what  is  known  of  the  fatal  effects  of  ultra-violet  light  rays 
upon  micro-organisms.  At  the  surface  of  the  earth  such 
organisms  are  to  a  large  extent  screened  from  the  effects  of 
these  rays  by  the  earth's  atmosphere,  but  this  would  not  be  the 
case  in  interplanetary  space. 

Even  if  we  were  able  to  prove  that  living  organisms  first 
reached  the  earth  from  some  other  planet,  however,  it  would 
not  help  us  in  the  least  to  understand  how  they  first  originated. 
Such  a  hypothesis  can  only  serve  to  remove  the  scene  of  action 
from  the  earth  to  some  unknown  sphere  where  the  investigation 
of  the  problem  is  altogether  beyond  our  reach.  We  may  just 
as  well  assume  at  once  that  the  first  terrestrial  organisms  were 
generated  in  situ  upon  the  earth  itself  and  endeavour  to  find  out 
how  such  generation  may  have  occurred. 

This  brings  us  to  our  second  alternative,  which  we  may  speak 
of  as  the  hypothesis  of  spontaneous  generation,  or,  if  we  prefer 
Huxley's  term,  abiogenesis.  The  discussion  of  this  question  has 
unfortunately  been  greatly  prejudiced  by  the  hasty  conclusions 
of  various  observers  who  from  time  to  time  have  announced  that 
they  have  actually  witnessed  the  production  of  living  organisms 
from  not-living  matter,  a  claim  which  has  been  repeated  at 
intervals  ever  since  people  began  to  speculate  on  such  subjects, 
but  which  no  one  has  yet  succeeded  in  substantiating.  I  shall 
refer  presently  to  the  latest  efforts  in  this  direction,  but  in  the 
meantime  we  must  carefully  bear  in  mind  that  the  sudden 
appearance  of  recognisable  organisms  where  none  previously 
existed,  and  in  situations  to  which  no  living  things  can  have 
gained  access,  is  a  very  different  thing  from  the  gradual  evolution 
of  living  matter  from  inorganic  substances  by  slow  and  imper- 
ceptible steps,  which  are  at  first  purely  chemical  and  physical  in 


266  the  president's  address. 

nature  but  gradually  assume  a  character  which  distinguishes 
them  more  or  less  from  ordinary  physical  and  chemical  processes 
and  perhaps  justifies  us  in  speaking  of  them  as  vital. 

That  there  should  be  perfect  continuity  between  not-living  and 
living  matter  on  the  one  hand,  and  between  physico-chemical  and 
vital  processes  on  the  other,  is  clearly  demanded  by  the  doctrine 
of  evolution.  Moreover  we  know  that,  at  the  present  day, 
inorganic  matter  is  constantly  being  converted  into  living  proto- 
plasm, though  only  by  the  peculiar  organising  activities  of 
living  bodies.  All  organisms  assimilate  materials  derived  from 
their  environment  in  order  to  build  up  their  own  bodies,  and  it 
is  largely  this  power  of  assimilation  that  distinguishes  them  from 
bodies  that  are  not  alive.  Daring  life  the  organism  conquers  its 
environment  and  appropriates  such  portions  of  it  as  it  requires. 
Death  is  the  conquest  of  the  organism  by  the  environment, 
accompanied  by  re-annexation  on  the  part  of  the  inorganic  world 
of  all  that  the  organism  had  appropriated  during  its  lifetime. 

The  chemist  has  no  difficulty  in  analysing  the  complex  col- 
loidal constituents  of  dead  organisms  into  a  descending  series 
of  less  and  less  complex  substances,  ending  with  the  so-called 
elements  themselves.  He  has  also,  to  a  very  great  extent,  accom- 
plished the  reverse  process,  and  has  already  carried  his  constructive 
operations  as  far  as  the  synthesis  of  polypeptides,  from  which 
point  to  the  proteids  themselves  is  but  another  step.  He  has  no 
right  to  assume,  however,  that  when  he  has  actually  taken  this 
step  and,  further,  mixed  his  proteids  with  the  other  substances 
known  to  occur  in  living  protoplasm,  he  will  have  produced 
anything  that  is  actually  endowed  with  life.  We  may  even  say, 
without  much  exaggeration,  that  the  chemist,  as  such,  has  no 
knowledge  of  protoplasm  at  all,  for  it  is  impossible  to  analyse 
protoplasm  while  it  is  alive,  and  as  soon  as  you  kill  it  it  ceases 
to  be  protoplasm. 

Even  the  simplest  living  things  known  to  us  behave  in  a 
manner  which  cannot,  at  any  rate  in  the  present  state  of  our 
knowledge,  be  explained  entirely  in  terms  of  chemistry  and 
physics.  The  living  organism  itself  plays  the  part  of  the  chemist 
and  the  physicist,  and  we  cannot  explain  the  chemist  or  physicist 
in  terms  of  the  chemical  and  physical  operations  which  he  per- 
forms in  his  laboratory.  Out  of  a  multitude  of  possibilities  the 
living  organism  selects  those  materials  and  those  modes  of  action 


THE    PRESIDENTS    ADDRESS.  267 

which  are  consonant  with  its  requirements  as  a  living  organism, 
and  its  power  of  meeting  emergencies  as  they  arise  is  the 
measure  of  its  power  to  survive.  Moreover,  it  is  able  to  profit 
by  experience  and  to  learn  how  best  to  overcome  the  difficulties 
presented  by  its  environment.  This  being  so,  we  are  justified  in 
maintaining  that  even  the  simplest  living  thing  is  endowed  with 
a  certain  degree  of  intelligence,  for  intelligence  is  nothing  but 
the  power  of  learning  by  experience  how  to  perform  purposive 
acts. 

We  are  not  obliged,  however,  to  suppose  that  the  property 
which  distinguishes  the  living  from  the  not-living — intelligence, 
vitality,  or  whatever  we  choose  to  term  it — came  into  existence 
suddenly.  It  is  more  in  accord  writh  our  experience  in  other 
directions  to  believe  that  it  arose  by  imperceptible  degrees, 
pari  passu  with  the  evolution  of  organic  from  inorganic  matter. 
This,  however,  must  not  be  taken  to  imply  that  there  is  no 
essential  difference  between  living  and  not-living  bodies,  either  in 
structure  or  behaviour.  We  might  with  equal  justice  say  that, 
because  water  is  a  compound  of  oxygen  and  hydrogen,  there  is 
no  essential  difference  between  water  and  a  mixture  of  these  two 
gases.  We  are  told  that  to  speak  of  the  aquosity  of  water  is 
meaningless  pedantry,  and  that  to  speak  of  the  vitality  of  living 
organisms  is  no  less  so.  Of  course,  if  such  phrases  are  offered  as 
explanations  of  phenomena,  they  are  entirely  valueless ;  but  if 
used  merely  as  a  kind  of  shorthand  expression  of  the  fact  that 
water  and  living  organisms  possess  certain  properties  which  dis- 
tinguish them  respectively  from  all  other  bodies,  I  see  no  more 
harm  in  them  than  in  any  other  technical  descriptive  terms.  In 
neither  case  can  we  supply  a  final  explanation  of  the  phenomena 
to  which  we  refer. 

Every  stage  in  the  evolution  of  matter  is  accompanied  by  the 
development  of  new  properties  or  qualities  which  require  the  use 
of  new  descriptive  terms.  As  to  the  so-called  forces  which  lie 
behind  these  properties  wTe  know  nothing.  We  can  only  classify 
them,  as  a  matter  of  convenience,  according  to  the  effects  which 
they  produce.  We  speak  of  the  force  of  chemical  affinity,  of  the 
force  of  gravity,  of  electro-magnetic  force,  and  so  on ;  and  if 
we  choose  to  express  our  conviction  that  none  of  the  so-called 
chemical  and  physical  forces  are  adequate  to  explain  all  the 
phenomena  of  life,  there  is  no  logical  reason  why  we  should  not, 


268  the  president's  address. 

as  a  matter  of  mere  convenience,  speak  of  vital  forces  also. 
Indeed,  it  appears  to  me  more  in  accord  with  scientific  method 
to  do  this  than  to  ignore  the  existence  of  such  characteristic  vital 
phenomena  as  our  own  consciousness  and  intelligence  or  leave 
them  to  be  explained  by  supernaturalism. 

After  all,  the  quarrel  between  the  vitalist  and  the  mechanist  is 
chiefly  over  mere  terminology.  The  vitalist  knows  perfectly  well 
that  the  organism  may  to  a  very  large  extent  be  looked  upon  as 
a  machine  in  which  chemical  and  physical  processes  are  utilised, 
and  the  mechanist  knows  equally  well  that  he  cannot  hope  to 
explain  his  own  consciousness,  and  his  own  intelligent  action, 
in  terms  of  chemistry  and  physics.  If  we  recognise  these  two 
facts  it  is  a  matter  of  comparatively  small  importance  to  decide 
in  what  terms  the  unknown  factors  can  best  be  described. 

At  any  rate  I  see  no  reason  why  vitalists  and  mechanists  should 
not  agree  that  living  organisms  first  arose,  either  on  our  own 
planet  or  elsewhere,  by  means  of  a  complex  process  of  physico- 
chemical  synthesis,  in  which  the  electron,  the  atom,  the  molecule, 
the  colloidal  mult  i- molecule  and  the  simplest  protoplasmic  unit, 
may  be  taken  as  representing  the  chief  stages.  This  at  any  rate 
is  what  we  should  expect  from  the  study  of  those  analytical  and 
synthetical  processes  with  which  the  bio-chemist  has  familiarised 
us,  and  from  what  we  know  of  the  process  of  evolution  in 
general. 

What  may  be  the  nature  of  the  simplest  protoplasmic  unit  is  a 
question  still  under  discussion.  That  it  is  not  what  we  commonly 
call  a  cell  seems  certain,  for  a  cell  has  a  complex  structure  which 
must  have  been  preceded  by  something  very  much  simpler.  The 
differentiation  into  cytoplasm  and  nucleus,  and,  above  all,  the 
extraordinarily  complex  phenomena  of  mitotic  division,  which  are 
observable  in  nearly  all  cases  where  a  distinct  nucleus  is  present, 
can  only  have  been  attained  as  the  result  of  a  long  process  of 
evolution.  The  existence  of  the  Bacteria,  in  which,  although 
both  cytoplasm  and  chromatin  may  be  present,  there  is  still  no 
properly  defined  nucleus,  perhaps  indicates  one  phylogenetic  stage 
through  which  the  fully  developed  cell  may  have  passed. 

Possibly  few  biologists  of  the  present  day  conceive  of  the  most 
primitive  organisms  as  relatively  large  unnucleated  masses  of 
structureless  protoplasm,  such  as  some  of  Haeckel's  famous 
Monera    were    supposed    to    be.       "  The   entire    body   of    these 


THE    PRESIDENT'S   ADDRESS.  269 

Monera,"  says  Haeckel,  "is  throughout  life  nothing  more  than  a 
motile  lump  of  slime  without  constant  form,  a  small  living  bit  of 
an  albuminoid  carbon  compound.  We  agree  that  this  homogeneous 
mass  possesses  a  very  complex  minute  molecular  structure ;  but 
this  is  not  anatomically  or  microscopically  demonstrable.  Simpler, 
less  perfect  organisms  are  not  thinkable."  * 

Recent  researches,  unfortunately,  tend  to  throw  considerable 
doubt  upon  the  existence  of  such  Monera.  It  has  been  pointed 
out  that  the  failure  to  recognise  a  nucleus  may  have  been  due  to 
the  imperfections  of  microscopical  technique  at  the  time  when  the 
organisms  in  question  were  described.  Even  some  of  the  Bacteria, 
which  Haeckel  regarded  as  Monera  and  which  are  amongst  the 
smallest  recognisable  organisms,  are  now  known,  as  we  have  just 
seen,  to  exhibit  well-marked  differentiations  in  their  protoplasm, 
and  many  of  the  supposed  "  cytodes  "  or  unnucleated  cells,  have 
already  been  shown  to  possess  a  nucleus.  With  regard  to  others 
the  matter  must  be  regarded  as  still  sub  judice. 

Haeckel  himself,  it  must  be  remembered,  recognised  the  fact 
that  his  Monera  must  be  composed  of  ultra-microscopic  molecules 
or  groups  of  molecules,  which  he  spoke  of  as  Plastidules  or 
Micellae,  the  latter  term  having  been  coined  by  Naegeli. 

It  is  these  ultra-microscopic  and  indeed  purely  hypothetical 
particles  of  colloidal  proteid  that  the  modern  biologist  is  inclined 
to  regard  as  representing  the  most  primitive  living  organisms, 
and  Weismann  has  gone  so  far  as  to  assign  to  them  a  definite 
place  in  our  scheme  of  classification,  proposing  for  their  recep- 
tion the  so-called  family  Biophoridae  and  identifying  them  with 
the  biophors  or  ultimate  vital  units  of  his  well-known  theory 
of  heredity. 

It  has  further  been  pointed  out  that  such  minute  particles  of 
living  matter,  far  smaller  than  the  most  minute  Bacteria,  may  be 
arising  all  around  us  by  so-called  spontaneous  generation  at  the 
present  day,  without  our  being  able  to  recognise  the  fact.  It  is 
only  when,  in  the  course  of  evolution,  they  had  become  aggregated 
in  relatively  large  masses,  that  we  could  hope  to  see  them  even 
with  the  highest  powers  of  our  microscopes.  The  justice  of  this 
view  might,  however,  fairly  be  questioned.  When  chemical  mole- 
cules   arise  in  our   laboratories   by  combination   of  atoms  or  of 

*  Translated  from  Haeckel's  "  Schopfungsgeschichte,"  Edition  9  (1898), 
p.  165. 


270  the  president's  address. 

simpler  molecules,  they  usually  present  themselves  to  us  in 
aggregates  which  are  large  enough  to  be  at  once  recognisable, 
and  one  would  naturally  suppose  the  same  to  be  true  of  the 
multi-molecules,  biophors,  or  whatever  we  like  to  call  them,  of 
which  living  matter  consists.  As  a  matter  of  fact,  however,  the 
chief  objection  that  I  can  see  to  the  Monera  theory  is  the 
almost  ultra-microscopical  size  of  the  simplest  organisms  actually 
known  to  us.  Indeed,  it'  we  take  into  account  the  so-called  filter- 
passers,  or  Chlamydozoa,  which  are  believed  to  be  the  germs  of 
certain  diseases,  but  most  of  which  we  know  only  by  inference, 
we  are  justified  in  saying  that  the  simplest  known  organisms  are 
actually  ultra-microscopic. 

It  seems  impossible  to  obtain  any  precise  information  as  to  the 
size  of  the  smallest  particles  that  can  be  seen  with  the  microscope. 
Since  this  address  was  delivered,  Dr.  Spitta  has  been  kind  enough 
to  inform  me  that  he  has  been  able  to  see  and  photograph  a 
particle  only  1/9 7,000th  of  an  inch  in  diameter,  and  it  will  be 
remembered  that  at  a  recent  meeting  of  the  Club  Mr.  Brown 
claimed  to  have  seen  in  the  frustule  of  a  diatom  a  pore  the 
diameter  of  which  he  estimated  at  1/200, 000th  of  an  inch.  As  the 
filter-passing  organisms  are  ultra-microscopic,  they  must  be  smaller 
than  this.  Indeed,  most  of  them  have  never  yet  been  seen  even 
with  the  aid  of  the  ultra -microscope,  which,  by  a  special  method 
of  illumination,  enables  us  to  recognise  the  presence  of  particles 
having  a  diameter  of  certainly  not  more  than  1/2, 500,000th  of  an 
inch  and  possibly  a  good  deal  less,  though  such  particles  cannot 
be  seen  at  all  in  the  ordinary  way  by  transmitted  light. 

It  is  only  by  inoculation  experiments  that  we  can  prove  the 
existence  of  these  ultra-microscopic  parasites.  Thus  we  are  told 
that  if  even  so  small  a  quantity  as  0'005  of  a  cubic  millimetre  of 
lymph  from  an  animal  suffering  from  foot  and  mouth  disease 
be  inoculated  into  a  healthy  calf,  the  latter  will  in  due  course 
contract  the  same  disease,  although  the  lymph,  so  far  as  micro- 
scopic examination  enables  us  to  judge,  is  entirely  free  from 
organisms. 

Yellow  fever,  cattle  plague,  rabies  and  many  other  diseases  are 
believed  to  be  caused  by  ultra -microscopic  parasites.  That  such 
diseases  are  due  to  living  organisms  and  not  to  lifeless  toxins  is 
indicated  sufficiently  clearly  by  the  fact  that  a  period  of  incu- 
bation always  follows  infection,  during  which  the  poisonous  matter 


THE    PRESIDENT'S    ADDRESS.  271 

increases  in  amount  until  there  is  enough  to  produce  its  deadly 
effects,  when  the  characteristic  symptoms  of  disease  manifest 
themselves  in  the  patient. 

Buckmaster  considers  that  most  of  the  filterable  parasites  are 
Bacteria,  but  as  we  know  nothing  of  their  structure  it  seems  a 
little  premature  to  include  them  in  any  group  which  is  based  upon 
morphological  characters.  They  might  be  included  in  Weismann's 
hypothetical  Biophoridae,  although,  from  the  point  of  view  of  the 
higher  organisms,  ;' death -carriers"  would  certainly  be  a  more 
appropriate  name  for  them  than  "  life-carriers." 

Inasmuch  as  all  the  known  filter-passing  organisms  are 
parasitic,  it  might  be  argued  that  their  existence  implies  the 
pre-existence  of  higher  organisms,  and  that  therefore  they  cannot 
be  regarded  as  themselves  representing  the  most  primitive  living 
things.  Such  an  argument  would,  of  course,  be  entirely 
fallacious.  It  so  happens  that  at  the  present  time  the  only 
means  we  have  of  recognising  the  most  minute  of  these 
organisms  is  by  their  effects  upon  other  organisms.  There  may 
be  hosts  of  ultra-microscopic  organisms  living  freely  on  the  earth's 
surface  which  have  no  recognisable  effects  upon  the  higher  plants 
and  animals,  and  of  whose  existence  we  therefore  remain  in 
complete  ignorance.  This  would  be  quite  in  harmony  with  what 
we  know  of  the  microscopically  visible  Bacteria.  Some  of  these 
live  freely  in  the  soil  and  are  able  to  feed  upon  purely  inorganic 
substances,  while  others  are  far  more  familiar  to  us  on  account 
of  their  influence,  whether  beneficial  or  disastrous,  either  upon 
ourselves  or  upon  other  organisms  in  which  we  happen  to  be 
interested. 

Your  late  President,  Prof.  E.  A.  Minchin,  who  speaks  with 
great  authority  on  such  subjects,  in  his  last  address  to  the  Club, 
devoted  some  time  to  the  consideration  of  the  question  whether 
the  extremely  minute  organisms  which  we  have  be?n  discussing 
consist  of  cytoplasm  or  chromatin,  and  pronounced  in  favour 
of  the  latter  alternative.  For  my  own  part  I  must  confess  that 
I  prefer  the  view  that  at  this  stage  of  evolution  the  distinction 
between  cytoplasm  and  chromatin  has  not  yet  arisen,  a  view 
which,  as  Prof.  Minchin  pointed  out,  is  in  harmony  Avith  the 
hypothesis  of  the  evolution  of  living  matter  from  inorganic  sub- 
stances on  the  earth  rather  than  with  that  of  its  importation 
from  some  other  planet. 


272  the  president's  address. 

It  follows  inevitably  from  the  above  considerations  that  the 
frequent  failure  of  experimenters  to  demonstrate  the  occurrence 
of  spontaneous  generation  cannot  be  regarded  as  proof  that  it 
never  takes  place  even  at  the  present  day  ;  much  less  as  proof 
that  it  has  never  taken  place  in  the  past. 

The  classical  experiments  of  Pasteur,  Tyndall  and  other 
observers  of  the  nineteenth  century,  so  far  as  they  related  to 
spontaneous  generation,  seem  to  have  been  for  the  most  part 
confined  to  the  problems  involved  in  the  occurrence  of  organisms 
in  organic  infusions,  such  infusions  being  the  media  in  which 
most  of  the  known  micro-organisms  naturally  occur  and  from 
which  they  derive  their  food-supplies.  As  a  result  of  such 
experiments  it  is  generally  believed  to  have  been  demonstrated 
clearly  enough  that  if  adequate  measures  are  taken  in  the  first 
place  to  sterilise  the  culture  media  by  heat,  and  in  the  second 
place  to  prevent  the  access  of  living  germs  after  sterilisation 
has  been  effected,  such  infusions  may  be  kept  for  an  indefinite 
time  without  any  organisms  making  their  appearance  in  them, 
and,  consequently,  without  undergoing  putrefaction.  It  is  also,. 
I  believe,  generally  supposed,  though  with  little  justification, 
that  this  conclusion  applies  to  all  culture  media  whatever, 
whether  organic  or  inorganic. 

One  observer,  however,  Dr.  Charlton  Bastian,  whose  earlier 
experiments  were  contemporary  with  those  of  Pasteur  and 
Tyndall,  and  who  has  recently  been  again  engaged  in  similar 
investigations,  has  consistently  maintained  a  different  view. 
His  earlier  experiments,  like  those  of  other  observers,  were  con- 
ducted with  organic  infusions,  or  with  artificial  nutrient  solutions 
such  as  ammonium  tartrate  or  other  salts  of  ammonia.  The 
positive  conclusions  arrived  at  by  experiments  with  organic 
culture  media  may  be  considered  to  have  been  completely  nega- 
tived by  the  general  experience  of  bacteriologists  during  the 
subsequent  forty  years. 

With  regard  to  the  origin  of  living  things  from  the  inorganic 
world,  however,  the  negative  results  obtained  by  properly  con- 
ducted experiments  with  organic  infusions  are  of  comparatively 
little  value.  If  spontaneous  generation  takes  place  at  all  at 
the  present  day  it  probably  takes  place  as  it  must  have  done 
at  some  time  in  the  past,  when  no  organic  bodies  existed  to 
supply    food    for    the    first  living   things.     In    other  words,    we 


THE    PRESIDENT'S    ADDRESS.  273 

should  not  expect  to  be  able  to  observe  spontaneous  generation 
in  infusions  of  organic  matter,  but  should  conduct  our  experiments 
with  purely  inorganic  substances. 

Dr.  Bastian's  a  priori  position  is  a  very  strong  one.  If 
spontaneous  generation  took  place  once  upon  the  earth's  surface- 
there  is  no  known  reason  why  it  should  not  take  place  to-day, 
while  the  actual  existence  of  countless  hosts  of  extremely 
primitive  organisms  alongside  the  most  highly  finished  products 
of  organic  evolution  certainly  seems  to  support  the  view  that  such 
primitive  forms  are  constantly  arising  from  inorganic  constitu- 
ents and  emerging  from  the  obscurity  of  their  birth  only  when 
they  have  reached  a  stage  of  evolution  at  which  they  are  capable 
of  appealing  directly  or  indirectly  to  the  human  senses. 

Dr.  Bastian  employed  for  some  of  his  recent  experiments*  a 
very  dilute  solution  of  sodium  silicate,  to  which  was  added  either 
a  minute  quantity  of  pernitrate  of  iron,  or  a  small  quantity  of 
phosphoric  acid  and  ammonium  phosphate.  He  joints  outr 
however,  that  the  sodium  silicate  is  a  variable  commercial  product 
and  attributes  to  this  fact  certain  otherwise  unaccountable 
variations  in  the  results  obtained.  The  experiments  were  there- 
fore repeated  with  pure  colloidal  silica  in  place  of  the  sodium 
silicate,  and  positive  results  were  again  secured. 

The  method  of  procedure  is  as  follows.  The  solution  to  be 
experimented  upon  is  hermetically  sealed  up  in  a  glass  tube 
and  heated  to  about  130°  C.  for  ten  minutes  or  more.  After  the 
lapse  of  a  few  weeks,  or  in  some  cases  months,  during  which  time 
the  sealed  tubes  have  been  exposed  to  ordinary  atmospheric 
conditions,  they  are  found  to  contain  living  organisms,  Torulaey 
Bacteria  and  even  moulds  being  present  in  varying  quantities. 
Dr.  Bastian  claims  that  these  organisms  have  arisen  in  the 
tubes  by  spontaneous  generation,  or,  as  he  terms  it,  Archebiosis. 
He  supposes  that  the  living  matter  probably  originated  in 
the  first  place  in  the  form  of  ultra-microscopic  particles,  but 
maintains  that  in  the  course  of  a  few  weeks  or  months  these 
particles  developed  into  the  organisms  finally  found. 

To  a  certain  extent  these  results  are,  as  I  have  already  pointed 
out,  in  accord  with  purely  a  ])riori  expectations,  but  in  other 
respects  they  appear  improbable  to  the  last  degree.     Most  of  the 

*  For  a  full  account  of  these  experiments  the  reader  is  referred  to 
Dr.  Bastian's  recent  book  on  The  Origin  of  Life.  2nd  Edition,  1913. 


274  the  president's  address. 

organisms  produced  are  of  well-known  types,  and  one  of  the 
moulds  formed  appears  to  be  a  Peniciliium  producing  spores 
in  the  ordinary  way.  I  must  confess  that  I  myself  find  it 
impossible  to  believe  without  much  stronger  evidence  that  such 
comparatively  highly  organised  beings  can  have  been  evolved  so 
rapidly  from  ultra- microscopic  germs.  We  are  accustomed  to 
think  of  evolution  as  a  very  slow  and  gradual  process,  and  we 
know  that  Bacteria,  Torulae  and  moulds  may  be  cultivated  for 
an  indefinite  period  without  undergoing  any  recognisable  change ; 
indeed  many  industries,  such  as  brewing,  wine-making  and 
cheese-making,  depend  for  their  very  existence  upon  this 
fact.  May  we  suppose  that  all  these  organisms  have  reached 
the  limits  of  their  evolution?  If  so  we  have  the  answer  to 
the  question,  why  have  they  remained  stationary  while  other 
organisms  have  developed  into  the  higher  forms  of  plants  and 
animals  ?  If,  however,  we  are  asked  to  believe  that  the  Bacteria 
and  Torulae  are  stages  in  the  evolution  of  the  moulds,  why  does 
not  this  transformation  manifest  itself  in  our  everyday  experience  ? 
Dr.  Bastian  himself,  it  should  be  observed,  is  a  convinced 
upholder  of  the  doctrine  of  heterogenesis,  or  the  sudden  appear- 
ance of  one  kind  of  organism  as  the  offspring  of  another,  but 
it  may  be  doubted  whether  any  other  living  biologist  holds  similar 
views. 

Again,  are  we  to  believe  that  such  organisms  arise  in  nature 
under  many  different  conditions  and  from  many  different 
mixtures  of  chemical  compounds,  or  are  we  to  believe  that 
Dr.  Bastian  has  accidentally,  and  almost  at  the  first  attempt, 
hit  upon  just  the  right  materials  and  the  right  conditions  for  the 
production  of  well-known  living  things  1  His  own  observations, 
if  correct,  show  that  the  experimental  solutions  may  be  varied 
within  wide  limits,  but  this  is  hardly  what  we  should  expect  if 
the  origin  of  living  things  is  to  be  regarded  as  a  mere  stage  in  a 
series  of  chemical  and  physical  processes.  Another  criticism 
of  these  results  may  be  based  upon  the  fact  that  the  materials 
employed  do  not  (unless  accidentally)  contain  all  the  necessary 
ingredients  of  protoplasm.  Carbon  is  apparently  entirely 
wanting,  and  we  must  either  suppose  that  it  is  accidentally 
present  in  minute  but  sufficient  quantities  as  an  impurity,  or 
else  that  it  can,  as  Dr.  Bastian  actually  suggests,  be  replaced, 
to  a  greater  or  less  extent,  by  silica  in  his  organisms.     It  has 


THE    PRESIDENT'S    ADDRESS.  275 

been  suggested  that  the  colloidal  character  of  the  silica  employed 
is  especially  favourable  to  the  evolution  of  living  matter,  but 
unless  the  organisms  are  largely  composed  of  silica,  which  is 
highly  improbable,  it  is  difficult  to  see  exactly  what  the  colloidal 
silica  has  got  to  do  with  their  origin,  unless,  indeed,  it  may  be 
supposed  to  act  as  a  catalytic  agent. 

Altogether  I  think  we  may  fairly  say  that  the  acceptance 
of  Dr.  Bastian's  results  would  involve  us  in  so  many  difficulties 
that  it  is  preferable  at  present  to  believe  that  there  has  been 
some  error  in  his  mode  of  procedure,  some  unsuspected  loophole 
through  which  contamination  of  his  preparations  has  taken 
place.* 

The  whole  problem  looks  surprisingly  like  a  modern  version 
of  the  old  story  with  which  we  started.  The  question  "  What 
was  the  origin  of  the  fossils  in  the  rocks  ? "  is  replaced  by  the 
question  "  What  was  the  origin  of  the  organisms  in  the  glass 
tubes  1 ':  We  have  seen  how,  in  the  former  case,  certain 
statements,  made  apparently  in  perfectly  good  faith,  led  to 
entirely  wrong  and  absurd  conclusions.  We  are  all  agreed 
now  as  to  how  the  fossils  got  into  the  rocks,  but  I  am  not  aware 
that  anyone  has  ever  succeeded  in  explaining  the  mystery  of 
how  the  marine  shells  got  into  the  human  body,  or  even  how 
the  toads  got  into  the  stones  in  which  they  were  alleged  to  have 
been  found.  .No  one,  however,  whose  opinion  is  worth  con- 
sidering, believes  that  they  were  generated  there.  All  are 
agreed  that  there  must  have  been  something  wrong  with  the 
original  statements,  and  there  we  must  be  content  to  leave 
it.  It  is  doubtless  premature  to  say  that  Dr.  Bastian's 
organisms  are  merely  toads  in  stones,  but  I  do  not  see  much 
to  choose  between  the  difficulties  of  explanation  in  the  two 
cases.  The  decision  must  be  left  to  the  future,  and  in  the  mean- 
time we  may  console  ourselves  with  the  reflection  that  science 

*  Since  this  address  was  written  Dr.  Bastian  has  published  a  lengthy 
communication  in  Nature  (January  22nd,  1914)  in  which  he  tells  us  that  his 
results  have  been  confirmed  by  four  other  observers,  two  in  America  and 
two  in  France.  The  American  observers  say,  however,  "  We  have  no  sug- 
gestion to  make  other  than  your  interpretation,  and,  indeed,  we  desire  to 
be  entirely  non-committal  as  yet."  Prof.  Hewlett,  the  well-known  bac- 
teriologist, writing  at  the  same  time,  states  that,  although  he  has  made 
similar  experiments,  he  has  not  yet  been  able  to  confirm  Dr.  Bastian's 
results. 

Journ.  Q.  M.  C,  Series  II.— No.  74.  20 


276  the  president's  address. 

cannot  be  infallible,  but  can  progress  only  by  a  process  of  natural 
selection,  in  the  course  of  which  one  hypothesis  replaces  another 
in  the  struggle  for  existence.  The  buckets  in  which  we  draw  up 
truth  from  the  bottom  of  the  well  are  very  small  and  very  leaky, 
and  a  good  deal  that  is  not  truth  finds  its  way  into  them  before 
they  reach  the  surface.  Fortunately  the  impurities,  even  if  they 
cannot  be  eliminated  at  once,  sooner  or  later  sink  to  the  bottom 
and  leave  the  water  clear. 


Journ.  Quekctt  Microscopical  Club,  Scr.  2,  Vol.  XII.,  No.  74,  April  1914. 


277 


A    CHANGER    FOR    USE    WITH    SUB-STAGE 

CONDENSERS. 

By  S.  C.  Akehurst,  F.R.M.S. 
Bead  October  2Mb,  1913. 

Figs.  1  and  2. 

Petrological  microscopes  have  been  fitted  in  various  ways  to 
arrange  for  a  quick  change  of  sub-stage  condenser,  and  I  have 
frequently   felt   the    need    of   a    similar    method    applied    to    a 


Fig  1. 

biological  microscope.  I  found  the  revolving  nose-piece  to  carry 
three  condensers  did  not  work  satisfactorily,  therefore  adapted 
the  principle  employed  in  the  sliding  objective  changer  to  the 
sub-stage  fitting,  and  found  this  enabled  me  to  get  an  easy  and 
rapid  change  of  condensers. 

The  scheme  consists  of  a  metal  slide  2|  x  If,  with  bevelled 
edges,  on  which  the  condenser  is  mounted,  and,  when  necessary, 
a  throw-out  arm  for  stops,  and  an  iris  diaphragm.    Two  D-shaped 


278      S.    C.    AKEHURST    ON    A    CHANGER    FOR    SUB-STAGE    CONDENSERS. 

metal  plates,  the  flat  sides  of  which  are  set  1|  inch  apart,  form 
a  groove  for  the  slide  to  work  in.  These  plates  are  screwed  to  a 
metal  collar,  the  diameter  of  which  is  such  as  to  allow  the  slide- 
condenser  changer  to  be  fitted  to  any  microscope  that  has  a  sub- 
stage  made  to  the  R.M.S.  gauge.  Fig.  1  shows  a  plan  of  the 
slide  changer  in  position,  while  fig.  2  gives  a  sectional  elevation 
along  the  line  A  B,  fig.  1.  When  three,  or  more,  condensers  are 
used  it  is  desirable  to  have  each  mounted  on  a  separate  slide ; 
but  when  only  two  condensers  are  used,  one  slide  may  be 
sufficient,  as  the  optical  parts  can  be  made  interchangeable. 


Fig.  2. 

When  the  slide  with  condenser  has  been  pushed  home,  a  screw, 
working  through  one  of  the  plates,  holds  this  firmly  in  position. 

This  changer  does  away  with  the  necessity  of  a  throw-out 
sub- stage,  and  any  variation  of  centrality  in  the  condenser  can 
be  adjusted  by  the  centring  screws  in  the  regular  way. 

To  rack  down  the  sub-stage  fitting,  withdraw  and  insert  a  new 
slide,  are  all  the  movements  that  are  required  to  obtain  a  change 
of  condenser,  and  this  can  be  effected  as  readily  as  a  change  of 
objective  on  a  revolving  nose-piece. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  74,  April  1914. 


279 


A  TRAP   FOR    FREE-SWIMMING   ORGANISMS. 

By  S.  C.  Akehurst,  F.R.M.S. 

{Bead  October  2H(h,  1913.) 

Fig.  3. 

Simply  stated  this  is  an  arrangement  which  cuts  off  the  retreat 
of  the  creatures  after  they  have  been  attracted  into  a  small 
receptacle  by  light. 

The  first  trap  I  used  was  made  of  glass — in  two  pieces.  The 
top  is  funnel-shaped,  and  holds  about  5  ounces  of  water.  This 
is  attached  to  a  horizontally-placed  cylinder,  1  inch  in  diameter, 
and  1|  inch  long  — the  whole  being  mounted  on  a  stem  and  foot. 

Into  the  cylinder  is  fitted  a  glass  spigot,  which  has  been  ground 
in  to  avoid  water  passing.  There  is  a  hole  at  the  bottom  of  the 
funnel  flask  which  allows  free  access  of  the  water  to  a  small  well 
in  the  glass  spigot. 

When  the  trap  is  working,  this  well  opens  immediately  under 
the  hole  at  the  bottom  of  the  flask,  and  into  this  the  organisms 
can  enter  freely.  When  desiring  to  fix  the  catch,  give  the  spigot 
a  slight  turn — the  mouth  of  the  well  then  presses  against  the  side 
of  the  cylinder  and  the  contents  become  locked  in. 

To  set  the  trap,  fill  the  flask  with  pond  water,  cover  the  entire 
funnel-shaped  flask  with  some  light-proof  material,  and  direct  all 
the  light  that  can  be  gathered  by  a  bull's-eye  on  to  the  cylinder 
winch  contains  the  glass  spigot.  Any  swimming  phototactic 
organism  in  the  water  will  at  once  react  and  pass  into  the  well, 
which  is  brightly  illuminated — usually  10  to  15  minutes  is 
sufficient  to  allow  for  this,  but  longer  time  can  be  given  if 
necessary.  Give  the  spigot  half  a  turn,  and,  as  already  explained, 
this  locks  the  creatures  in  the  well.  The  water  can  then  be 
poured  off  from  the  flask,  the  spigot  withdrawn,  and  the  rotifers — 
or  whatever  may  have  been  trapped  in  the  well — can  be  taken 
up  with  a  pipette  and  transferred  to  the  slide  for  examination. 

After  the  first  catch  has  been  taken  the  trap  can  be  set  again  and 
a  second  lot  secured.  Work  can  therefore  be  carried  on  without 
interruption  or  loss  of  time  until  all  the  water  has  been  dealt  with. 

Should  there  be  any  sediment,  this  can  be  allowed  to  settle  and 
then  trapped  off  before  any  attempt  is  made  to  catch  the  organisms. 

There  is  difficulty  in  obtaining  this  trap  made  in  glass ;  I  have 
therefore  worked  out  another  in  metal  (fig.  3).  This  consists  of 
a  round  box,  1  inch  in  depth,  3|  inches  in  diameter — the  top  and 
bottom  slightly  convex — mounted  on  a  tripod.  A  hole  in  the 
bottom  allows  the  water  to  pass  through  a  short  tube,  which  is  in 
three  sections,  the  first  part  metal,  the  second  rubber  and  the 
third  glass.  A  pinch-cock  can  be  applied  to  the  rubber  con- 
nection, which  will  prevent  water  passing  when  the  glass  tube 
has  been  removed  for  examination  of  contents. 


280       S.    C.    AKEHURST    ON    A    TRAP    FOR    FREE-SWIMMING    ORGANISMS. 

I  have  departed  from  the  funnel  shape — making  the  metal 
box  to  hold  the  water  almost  flat,  which  will  allow  any  sediment 
to  settle  at  the  bottom.  If  the  water  is  very  muddy,  a  cork  can 
be  fitted  into  the  outlet  hole  and  left  until  the  debris  has  settled 
— first  filling  the  tube  with  clean  pond  water. 

If  the  cork  is  carefully  removed,  very  little,  if  any,  dirt  will 
pass  down  the  tube.  Should  some  slip  by,  this  can  be  trapped 
off,  the  tube  refilled  with  water,  when  a  perfectly  clear  gathering 
can  be  secured. 

A  strainer  is  provided,  to  be  used,  when  necessary,  for  removing 


Fio  3. 


larvae  or  any  of  the  entomostraca.     It  is  important,  that  as  much 
light  as  possible  should  be  concentrated  on  the  glass  tube. 

To  arrange  for  this  a  bi-convex  lens  1|  inch  diameter,  silvered  on 
one  side  and  mounted  in  a  metal  holder  with  a  movable  support 
allowing  it  to  be  tilted  at  an  angle,  is  placed  under  the  tube,  light 
from  a  bull's-eye  condenser  is  received  by  the  lens  and  a  bright 
beam  passed  up  the  tube.  This  method  of  transmitting  the  light 
is  very  effective,  and  the  trap  in  consequence  acts  more  rapidly 
and  effectively  than  when  the  bull's-eye  condenser  only  is  em- 
ployed. The  lens — placed  in  position — is  shown  in  the  illustration. 


Journ.  QueketL  Microscopical  Club,  Ser.  2,  Vol.  XII. ,  No.  74,  April  iyi4. 


281 


AN    IMPROVED   FORM   OF   CHESHIRE'S   APERTO- 

METER. 

By  Edward  M.  Nelson,  F.R.M.S. 

(Exhibited  and  described  by  James  Grundy,  F.R.M.S.,  October  28th,  1913.) 

Fig.  4. 

Of  the  value  of  Mr.  Cheshire's  form  of  Apertometer  there  can  be 
no  doubt.  The  aim  of  Mr.  Kelson  has  been  to  enable  the  N.A. 
of  an  objective  to  be  read  on  the  Apertometer  with  greater  ease 
and  accuracy. 

Distinctness  and    clearness  of  reading  have  been  effected  by 

APERTOMETER     OlAGRAM 
/S.    -  1    >nch. 


(ffcfj) 

Fig.  4. 

increasing  the  number  of  marked  values  of  N.A.  from  9  to  22, 
without  the  confusion  that  overcrowding  of  the  lines  would  entail. 
To  accomplish  this,  short  arcs  of  circles  are  used  instead  of  whole 
circles.  A  valuable  property  of  these  is  the  clear  visibility  of  the 
ends  or  edges  of  the  arcs ;  they  are  seen  more  distinctly  than 
complete  circles  would  be.  The  contrast  between  the  white 
ground  and  the  short  black  lines  favours  this. 

The  exterior  edges  of  the  arcs  denote  the  N.A.,  and  thus  give 
most  convenient,  accurate  and  definite  positions  for  reading. 


282    E.  M.  NELSON,  AN  IMPROVED  FORM  OF  CHESHIRE'S  APERTOMETER. 

The  first  or  lowest  marked  value  is  0'05  N.A.,  and  the  values 
increase  by  increments  of  0'05  up  to  0'5  N.A.  From  0*5,  the 
values  increase  by  0*033  up  to  0*9  N.A. 

The  apparatus  consists  of  an  Apertometer  diagram  (fig.  4) 
printed  on  a  small  card  about  the  same  size  as  Mr.  Cheshire's 
form,  another  card  of  explanations  and  instructions,  a  cubic  inch 
of  wood  and  a  metal  diaphragm  with  a  hole  not  more  than 
1*25  mm.  in  diameter.  Mr.  Nelson  lays  some  stress  on  the  hole 
in  the  diaphragm  being  not  more  than  1'25  mm.  in  diameter. 
He  says:  "If  the  hole  is  larger  than  that,  some  objectives, 
especially  low  powers,  will  read  a  great  deal  too  high.  And 
accuracy  is,  relatively,  more  important  with  the  small  apertures, 
because — for  example — an  error  of  O'Ol  or  0*02  will  make  a  far 
greater  percentage  of  difference  than  it  would  with,  say,  the 
N.A.  of  an  oil-immersion  objective.  If  1*25  and  1*27  be  com- 
pared with  the  N.A.  0*11  and  0*13  of  a  3-inch  objective,  the 
actual  difference  between  the  two  pairs  of  values  is  0*02  in  each 
case,  but  the  percentage  difference  with  the  higher  N.A.  is  only 
1*6  as  compared  with  18  in  the  case  of  the  low  values." 

In  this  connection,  Mr.  Nelson  has  made  another  important 
remark,  namely,  "  The  working  aperture  is  larger  than  the 
correctly  measured  true  aperture,  so  that  low  powers  resolve  more 
than  they  are  entitled  to  theoretically.  This  is  probabhy  due  to 
the  practically  enlarged  aperture  caused  by  the  rolling  motion 
of  the  eye  from  side  to  side." 

It  will  also  be  noticed  that  the  diaphragm  to  be  used  with  the 
apertometer  is  made  convex  on  one  side,  and  if  the  convex  side 
is  put  into  the  larger  aperture  of  an  eye-piece — or  other — 
diaphragm,  it  rests  steadily  in  position. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII. ,  Ko.  74,  April  1914. 


28 


n 


TWO  SIMPLE  APERTOMETERS  FOR  DRY  LENSES. 

By  Frederic  J.  Cheshire,  F.R.M.S. 

{Read  October  2$th,  1913.) 

Figs.  5  amd  6. 

In  dealing  with  questions  of  apertometry  it  is  very  important  to 
inquire,  in  the  first  place,  as  to  what  order  of  accuracy  it  is 
desirable  to  work.  No  useful  purpose  would  be  served  by  giving 
a  carpenter  a  foot-rule,  divided  to  hundredths  of  an  inch,  with 
which  to  measure  the  length  of  a  plank.  The  measurement, 
if  made  to  such  an  order  of  accuracy,  would  be  useless  and 
meaningless. 

Prof.  Abbe,  in  "  Some  Remarks  on  the  Apertometer"  {Journal 
of  the  Roy.  Jlic.  Soc.  1880,  p.  20),  after  stating  that  the  error  of 
measurement  in  his  well-known  apertometer  is  limited  to  about 
|  per  cent.,  goes  on  to  say  that  "an  exactness  of  reading 
to  this  extent  is  evidently  more  than  sufficient.  An  unavoidable 
amount  of  uncertainty  resulting  from  the  nature  of  the  object, 
and  many  other  sources  of  slight  error,  will  always  limit  the 
real  exactness  of  observation  beyond  1  per  cent,  of  the  unit, 
different  observers  and  different  methods  of  equal  reliability 
being  supposed.  In  low  powers  slight  variations  in  the  length 
of  the  tube,  in  high  powers  slight  alterations  of  the  cover- 
adjustment,  will  admit  of  much  greater  difference  than  the 
error  of  reading  will  introduce.  It  should  be  observed  that 
in  high-angled  objectives  the  aperture  has  not  the  same 
value  for  different  colours,  owing  to  the  difference  of  focal 
length  (or  amplification),  even  in  objectives,  which  are  perfectly 
achromatic  in  the  ordinary  sense.  In  the  case  of  very  large 
angles,  the  aperture,  angular  or  numerical,  will  be  greater  for 
the  blue  rays  than  for  the  red,  generally  by  more  than  i  per 
cent.  Last,  not  least,  there  is  no  possible  interest,  either 
practical    or   scientific,   appertaining    to    single    degrees,  or  half 


284     F.   J.   CHESHIRE,   TWO    SIMPLE    APERTOMETERS    FOR    DRY    LENSES. 

•degrees,  of  aperture  angles ;  for  no  microscopist  in  the  world  will 
be  able  to  make  out  any  difference  in  the  performance  of  objec- 
tives as  long  as  the  numerical  apertures  do  not  differ  by  several 
per  cent.,  other  circumstances  being  equal." 

"  For  these  reasons  I  consider  all  attempts  at  very  accurate 
measurements  of  this  kind  to  be  useless." 

No  one,  probably,  is  likely  to  have  the  temerity  to  question 
the  authority  of  Prof.  Abbe  on  such  a  question  as  Apertometry, 
so  that  we  can  accept  his  limit  of  1  per  cent,  with  confidence. 

Fig.  5  shows  a  plan  of  a  form  of  apertometer  for  dry  lenses 
which  for  simplicity  in  use  and  for  the  accuracy  of  its  results 
probably  leave  nothing  to  be  desired.  A  strip  of  vulcanite  A  * 
is  so  divided  that  the  distance  D  of  any  line  from  the  zero  of  the 
scale  is  given  by  the  equation 

D  =  2  A  tan  (sin-i  n.A.) 

set  out  in  this  Journal  for  April  1904  (Ser.  2,  vol.  ix.  p.  1),  in 
the  article  on  "  Abbe's  Test  of  Aplanatism,  etc."  The  graduations 
are  marked  with  the  corresponding  N.A.  values  for  a  value  of  A 
equal  to  25  mm.  In  use  the  apertometer  is  placed  upon  the 
.stage  and  the  object  plane  of  the  lens  to  be  tested  adjusted  at  a 
height  of  25  mm.  above  the  plane  of  the  scale.  The  upper  focal 
plane  of  the  objective  is  then  observed  in  any  known  way  and  the 
apertometer  adjusted  on  the  stage  until  the  inner  edge  of  the 
fixed  white  block  B  is  seen  on  one  edge  of  the  objective  opening. 
This  adjustment  effected,  the  sliding  white  block  C  is  slid  along 
the  strip  A  until  its  inner  edge  is  seen  on  the  opposite  edge  of  the 
objective  opening  to  that  on  which  the  block  B  is  just  seen. 
The  N.A.  value  found  opposite  to  the  inner  edge  of  the  block  0 
on  the  scale  is  that  of  the  lens  tested. 

The  graduations  from  0  to  0*9  N.A.  proceed  by  steps  of  0*02 
and  from  0-9  to  0*96  N.A.  by  steps  of  0-01. 

Fig.  6  shows  a  modification  of  the  form  of  apertometer 
described  in  my  original  paper  in  1904.  I  have  substituted  for 
the  concentric  circles  there  shown  curved  lines  which  project 
optically  into  the  upper  focal  plane  of  the  lens  being  tested  as  a 
number  of  equi-distant  straight  lines  of  equal  thickness.  The 
projected  image  of  the  apertometer  scale  is  thus  a  simple  linear 

*  The  right-hand  end  is  shown  broken  off. 


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286     F.   J.   CHESHIRE,    TWO    SIMPLE    APERTOMETERS    FOR    DRY    LENSES. 

scale  upon  which  N.A.  values  can  be  read  directly.  The  scale 
runs  from  00  to  0*9  N.A.  by  steps  of  0*05,  i.e.  the  divisions 
starting  from  the  centre  have  the  values  0,  0'05,  0"10,  015,  0-20, 
etc.,  of  N.A. 

The  short  curved  lines  of  the  scale  should  strictly  be  hyperbolas, 
but  such  curves  are  very  difficult  to  draw  accurately,  and  it  was 
not  until  my  son,  Mr.  R.  W.  Cheshire,  suggested  to  me  that  they 
might  be  replaced  by  arcs  of  circles  with  curvatures  equal  to 
those  of  the  corresponding  hyperbolas  at  their  vertices  that  the 
apertometer  described  became  a  practical  construction. 

I  may,  perhaps,  be  allowed  to  avail  myself  of  this  opportunity 
to  say  that  in  my  opinion  there  are  several  objections  to 
Mr.  Nelson's  form  of  the  Apertometer  which  was  introduced 
by  me  in  1904.  These  may  be  briefly  indicated.  In  the  first 
place,  no  advantage  can  result  from  the  use  of  the  outer  edges 
of  the  lines,  instead  of  the  middles,  as  is  usually  done,  as  the 
part  of  the  lines  from  which  distances  and  therefore  NA.'s 
must  be  estimated  by  eye.  Further,  in  Mr.  Nelson's  form  the 
thickness  of  the  lines  varies  in  different  parts  of  the  diagram, 
and  has  no  assigned  or  stated  thickness  in  terms  of  N.A.  This, 
I  think,  is  a  fatal  defect,  because  when  the  thickness  of  a  line 
has  a  N.A.  value  of  0-02,  say,  such  thickness,  especially  when 
dealing  with  low-power  lenses,  provides  an  invaluable  standard 
of  reference  when  estimating  by  eye  N.A.  values  intermediate 
to  those  represented  on  the  scale. 

In  apertometers  of  the  kind  in  question  the  further  the  sub- 
division of  the  scale  is  carried  the  greater  must  be  the  complexity 
of  the  image  presented  to  the  eye — the  advantage  of  one  is 
balanced  by  the  disadvantage  of  the  other.  Possibly,  however, 
most  people  would  prefer  the  simplicity  of  a  diagram  with  the 
larger  divisions  to  the  optical  Hampton-Court-maze  necessitated 
by  the  smaller  ones. 


Joum.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  74,  April  1914. 


287 


A  VARIATION   OF   CHESHIRE'S   APERTOMETER. 

By  M.  A.  Ainslie,  R.N.,  B.A.,  F.R.A.S. 
.(Read  October  2Sth,  1913.) 

Figs.  7  and  8, 

Experience  in  the  use  of  both  the  original  forms  of  Cheshire's 
Apertometer,  and  the  modification  thereof  recently  introduced 
by  Mr.  E.  M.  Nelson,  has  revealed  one  or  two  difficulties  in 
connection  with  the  reading  of  the  instrument — that  is,  if  any 
accuracy  in  the  second  place  of  decimals  is  required — and  the 
present  instrument  is  an  attempt  at  removing  these. 

The  first  difficulty  is  due  to  the  fact  that  in  Mr.  Cheshire's 
instrument  we  have  to  interpolate  or  estimate  between  two 
divisions  on  a  scale,  one  of  which  is  not  visible,  being  outside 
(apparently)  the  margin  of  the  back  lens  of  the  objective,  This 
renders  the  estimation  of  the  second  place  of  decimals  in  the 
N.A.  uncertain,  and  although  Mr.  E.  M.  Nelson's  modification 
of  the  original  instrument  is  somewhat  better  in  this  respect — 
yet  the  very  means  adopted  to  improve  the  reading,  namely, 
the  introduction  of  a  large  number  of  additional  circles — is 
likelv  to  confuse  the  diagram  and  bewilder  the  observer. 

In  either  the  old  form  or  the  new  of  Cheshire's  instrument, 
a  count  has  to  be  made  of  concentric  circles ;  a  thing  which, 
simple  as  it  may  seem,  is  peculiarly  liable  to  confuse  the  eye  ;  so 
that  it  is  only  after  counting  several  times  that  one  feels  certain 
that  the  number  is,  say,  eight  and  not  seven.  In  the  present 
instrument  a  totally  different  method  of  reading  is  adopted  ;  the 
diagram  is  simplified,  and  the  estimation  of  the  second  place  of 
decimals  is  merely  the  estimation  of  the  point  where  a  spiral 
curve  cuts  the  margin  of  the  back  lens  of  the  objective,  referred 
to  two  points,  one  on  each  side,  where  radial  lines  cut  the 
same. 

The   instrument,   which   consists,  in  the  form  for  dry  lenses, 


288     M.    A.    AINSLIE    ON    A    VARIATION    OF    CHESHIRE'S    APERTOMETER, 

of  a  card  diagram  placed  on  the  stage,  is  constructed  as  follows- 
(%  7): 

A  series  of  radial  lines  are  drawn  from  a  common  centre, 
making  equal  angles  with  one  another  ;  the  precise  number  is- 
immaterial,  but  it  has  been  found  convenient  to  divide  the  circle 
into  sixteen  equal  parts.  One  of  these  (preferably  that  lying^ 
horizontally)  is  selected  as  a  zero,  and  points  are  marked  off 
along  the  others  at  distances  equal  to  a  constant  length  (usually 
25  mm.,  or  1  inch)  multiplied  by  the  tangent  of  the  semi-angle 
of  aperture ;  i  e.  the  tangent  of  the  angle  whose  sine  is  the- 
numerical  aperture.  This  is  done  for  every  (H  of  N.A.,  and 
a  spiral  curve  drawn   through  the  points    thus  obtained  ;   this. 


Fig.  7. 


curve  being   repeated,   turned  through    180°.       The   curves  are 
shown  with  fair  accuracy  in  fig.  7. 

The  diagram  is  used  precisely  as  the  Cheshire  Apertometer  : 
either  the  objective  is  focused  on  the  upper  surface  of  a  cube  of 
wood  as  in  the  Cheshire  instrument ;  or  else  a  pinhole  in  the 
centre  of  the  diagram  is  focused,  and  the  body  racked  back 
25  mm.,  or  1  in.,  this  being  measured  easily  enough  with  a 
scale.  This  latter  method  is  preferable  for  objectives  of  high 
aperture.  A  |low-power  eye-piece  is  employed.  On  examining 
the  Ramsden  disc  with  a  hand  lens  (a  watch-maker's  eye-glass 
does  well)  the  appearance  in  fig.  8  is  seen,  and  the  method  of 
estimating  the  value  of  the  N.A  is  fairly  obvious  ;  we  have  only 
to  start  from  the  zero  and  count  in  the  direction  of  the  spiral, 


M.    A.    AINSLIE    ON    A    VARIATION    OF    CHESHIRE'S    APERTOMETER.     28i> 

(H  for  each  radial  line  passed  over  ;  the  second  figure  is  found  by 
estimating  the  position  between  two  adjacent  radial  lines  of  the 
point  where  the  spiral  cuts  the  margin  of  the  back  lens.  In 
tig.  8,  for  example,  the  N.A  is  about  0-73. 

The  procedure  is  the  same  with  the  form  suited  to  immersion 
lenses  ;  the  upper  surface  of  a  plate  of  glass  is  focused,  and  the 
diagram  is  balsamed  to  the  lower  surface.  It  might  be  pre- 
ferable to  have  12  radial  lines  instead  of  16,  and  read  like 
a  clock  ;  this  is  a  matter  for  experiment. 

Of  course  the  value  of  the  radius  vector  of  the  curve  for 
a  diagram  in  optical  contact  with  glass  will  not  be  quite  the 
same  as  before ;  instead  of  r  =  C  tan  <£,  where  sin  <£  =  N,  we 


8 


Fig.  8. 


shall  have  r  =  C  tan  <£'  where  /x  sin  <£'  =  N\  but  the  principle 

is  the  same.  » 

The  equation  to  the  curve  presents  some  interesting  features; 

aO 

where  C  is  the  distance  of   the   diagram 


it  is  r  =  C—r_ 


V  1  —  a202 

from  the  lower  focal  plane  of  the  objective  and  a  is  a  constant 
depending  on  ll  and  on  the  number  of  radial  lines  in  the  circle ; 

for  16  radial  lines,  and  /x  =  1   (dry  form),  a  =  ^— .      The  radius 

representing  N.A.  =  I/O  is  obviously  an  asymptote  to  the  curve  ; 
in  the  case  of  the  glass  form,  N.A.  =  /x  will  be  the  asymptote. 

It  is  of  interest  to  note  that  the  same  curve  will  serve  for  any 
refractive  index  of  the  medium  beneath  which  it  is  mounted  :  if 


290     M.    A.    AINSLIE    ON    A    VARIATION    OF    CHESHIRE'S    APERTOMETER. 

we  change  the  refractive  index  from  1  to  ju,  we  merely  have  to 
close  up  the  radial  lines  in  that  ratio,  leaving  the  curve  unaltered. 
For  instance,  if  we  had  16  radii  for  the  dry  form  we  could  use 
the  same  curve,  but  with  24  radii,  for  a  plate  of  glass  of 
fx  =  15. 

In  practice  the  instrument  proves  of  great  utility,  and  very 
reliable  and  easily  used.  All  that  is  necessary  is  to  be  accurate 
in  centring ;  this  is  easily  seen  to  be  correct  when  the  reading  of 
each  end  of  the  spiral  is  the  same. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  74,  April  1914. 


291  AfclC 


ON   THE   DISC-LIKE   TERMINATION    OF   THE 
FLAGELLUM    OF   SOME    EUGLENAE. 

By  James  Burton. 

(Bead  November  25th,  19130 

About  two  years  ago,  one  of  our  members — Mr.  Ellis — was 
exhibiting  here  living  Euglena  viridis.  During  the  evening  the 
creatures,  presumably  affected  by  the  light,  heat  and  confine- 
ment of  the  life-slide,  threw  off  their  flagella ;  it  was  perhaps  a 
preparatory  step  to  encystment,  or  even  to  their  death,  under 
the  unnatural  conditions  of  their  environment.  In  the  field  of 
the  microscope  there  were  numbers  of  these  organs  floating 
free,  and  in  the  case  of  many  of  them,  if  not  quite  the  ma- 
jority, they  were  terminated  by  what  appeared  to  be  a  small 
disc  or  bulb.  We  were  greatly  interested  in  the  phenomenon, 
and  decided  to  investigate  it.  Mr.  Ellis  soon  after  wrote  a 
letter  to  The  English  Mechanic,  describing  what  he  had  seen,  and 
inquiring  if  any  one  else  had  had  a  similar  experience.  There 
were  no  very  definite  answers,  no  one  claiming  to  have  noticed 
this  occurrence  before.     In  his  letter  he  says  : 

"  On  turning  on  the  one-sixth,  something  quite  out  of  the 
ordinary — at  least,  to  me — was  seen  in  the  shape  of  minute 
transparent  discs,  each  with  a  long,  thick,  but  motionless  fla- 
gellum,  and  apparently  associated  with  the  resting  Euglenae, 
around  which  they  appeared  most  plentiful.  For  some  time  I 
was  puzzled  to  account  for  these  objects,  until,  noting  the 
obvious  similarity  in  length  and  thickness  between  their  flagella 
and  those  of  the  motile  Euglenae,  I  became  convinced  they  were 
one  and  the  same,  they  having  been  thrown  off*  bodily  by  the 
exhausted  Euglenae,  and  not  retracted — as  is  usual,  I  under- 
stand." .  .  .  "  Now  here  comes  the  difficulty  :  What  is  the  little 
disc  to  which  the  flagellum  is  attached  ?  Is  it  the  '  knob-like 
inflated  distal  extremity  '  of  a  flagellum  belonging  to  'an  interest- 
ing local  variety  of  E.  vi?'idis'  described  by  a  writer  in  Science 
Gossip  for  October  1879,  and  referred  to  by  Saville-Kent  on 
p.    382   of   his    '  Manual    of    the   Infusoria,'    and   illustrated    on 

Jourx.  Q.  M.  C,  Series  II.— No.  ~±.  21 


292  J.    BURTON    ON    THE    DISC-LIKE    TERMINATION    OF    THE 

PI.  xx.  fig.  29  ? "  Saville-Kent  says,  in  the  paragraph  referred  to : 
"  An  interesting  local  variety  of  E.  viridis  has  been  recently 
described  by  Mr.  M.  H.  Robson,  of  Newcastle-upon-Tyne,  in 
which  the  distal  extremity  of  the  flagellum  presents  an  inflated 
knob-like  aspect,  as  shown  at  PI.  xx.  fig.  29.  Possibly  such 
modification  of  this  important  organ  represents  a  phase  pre- 
liminary to  its  entire  withdrawal,  and  antecedent  to  the 
entrance  of  the  animalcule  upon  the  encj7sted  or  resting  stage." 

In  Science  Gossip  (1879)  there  are  several  letters  about  the 
phenomenon,  one  on  p.  231  by  Mr.  Robson,  with  the  original 
drawing  from  which  Saville- Kent's  figure  is  taken,  and  also  two 
other  forms  of  Euglenae  with  identical  organs.  Referring  to 
them,  Mr.  Robson  says:  "These  may  be  of  interest,  as  I,  at  all 
events,  have  not  met  an  observer  who  has  previously  noted  this- 
peculiarity."  In  a  letter  on  p.  136  another  writer  mentions  a 
case  where  in  a  large  number  of  Euglenae  "  the  flagellum  was  in 
each  case  bulbed."  And  he  draws  the  singular  conclusion  that 
these  were  not  true  Euglenae,  but  suggests  they  may  have  been 
a  larval  form  of  the  rotifer  Hydatina  senta.  In  a  letter,  p.  159,. 
Mr.  Robson  writes  of  E.  viridis  and  its  "  sucker  bulb,"  and  of  the 
existence  of  "  the  bulb  siphon,  sucker,  or  whatever  it  is."  On 
p.  256  there  is  a  letter  from  Mr.  George  headed,  "  E.  viridis  and 
its  bulbed  flagellum,"  and  he  makes  reference  to  the  fact  that 
"  on  one  occasion,  whilst  closely  watching  the  contortive  move- 
ments of  a  full-grown  specimen,  I  was  much  surprised  to  see  the 
little  animal  '  bite  off",'  if  I  may  so  term  it,  the  flagellum,  which 
immediately  floated  away."  It  is  clear  at  least  from  all  this  that 
observers  a  good  many  years  ago  saw  the  structure,  and  that  it 
created  a  good  deal  of  interest  and  some  speculation  as  to  the  true 
interpretation  of  the  appearance. 

Now,  to  return  to  Mr.  Ellis's  question,  "  What  is  the  little 
disc "  attached  to  the  distal  end  of  the  flagellum  of  some 
Euglenae  ?  After  some  considerable  attention  to  the  subject,, 
and  observation  of  many  examples,  I  have  come  to  the  conclusion 
that  there  is  no  disc,  no  bulb  or  sucker,  or  anything  of  the  kind 
at  the  end  of  the  flagellum.  The  appearance  which  has  given 
rise  to  the  idea  can  be  correctly  accounted  for  in  another 
manner.  I  have  often  seen  the  disc  since  Mr.  Ellis  first  called 
attention  to  it,  but  do  not  remember  ever  seeing  it  on  a  flagellum 
in  active  use  by  a  healthy  Euglena ;  in  fact,  it  is  almost  impos- 


FLAGELLUM  OF  SOME  EUGLENAE  293 

sible  to  see  the  flagellum  at  all  when  the  creature  is  in  full  vigour 
— it  is  then  usually  being  lashed  about,  and  is  bent  and  twisted  in 
all  directions.  It  will  be  noticed  that  Mr.  Ellis  only  claims  to 
have  seen  the  disc  when,  for  some  reason,  the  organ  to  which  it 
was  attached  was  thrown  off. 

He  says  :  "  Out  of  all  the  numberless  motile  Euglenae  which 
were  swimming  about  amongst  their  resting  kindred,  not  one  was 
seen  with  a  flagellum  having  a  knob  at  its  free  extremity." 

Neither  do  I  think  any  of  the  writers  in  Science  Gossij)  dis- 
tinctly claim  to  have  seen  it  on  a  healthy,  active  animal.  But 
when  the  flagellum  is  thrown  off — "  bitten  off,"  as  has  been 
described — or  when  the  Euglena  is  killed  by  a  careful  application 
of  iodine,  it  is  not  at  all  infrequent,  and  I  have  seen  it  on  speci- 
mens from  many  different  localities. 

It    happened    that    since   I   thought  of    bringing    the  subject 
before  you  I  was  looking  over,  for  quite  another  purpose,  a  slide 
of    Euglenae    mounted    in    April    1911.     I    there  found  several 
instances   of   discs   still   attached.      Some    creatures,    and    some 
Euglenae  at  all  events,  occasionally  carry  the  flagellum  stretched 
out  rigidly  in  front,  with  a  small  portion  of  the  distal  end  thrown 
into  a  coil  or  spiral  form,  usually  rapidly  moving.     Now  if  the 
creature  were  killed  with  the  organ  in  that  position,  or  for  any 
reason  threw  it  off,  it  seems  to  me  very  probable  that  the  coil — 
there    might    be    but    one  turn    in     it — would  present   just   the 
appearance  we  have  had  referred  to  as  a  disc  or  bulb,  and  that, 
consisting  of  protoplasm,  it  would   be  very  likely  to  adhere  where 
touching  another  part,  and  so  retain  its  form  as  a  circle.     With 
the  use  of  an  immersion  objective  and  careful  illumination,  it  has 
seemed  to  me  possible  to  make   out  a  part  of  the  circle  as  being 
thicker  or  darker  than  the  rest,  owing  to  the  thread  overlapping 
at  that  point.      It  must  be  remembered  that  we  are  dealing  with 
a  very  small  and  very  transparent  structure,  not  easy  to  demon- 
strate correctly.     Moreover,  among  the  others,   killed  by  iodine 
or  mounted,  it  is  easy  to  find  specimens  with  the  flagellum  much 
twisted  and  thrown  into  "  kinks."     So  that   there  are  often  small 
circles   at    the  sides   instead  of  at  the  end  of  the  thread,   and 
although  these  have  just  the  same  appearance   as  those  at  the 
end,  I  do  not  think  any  one  would  suggest  that  it  is  likely  a  disc 
or  bulb  would  occur  in  such  a  situation,  to   say  nothing   of  the 
im probability  of  there  being  more  than  one,  and  these  often  on 


294  J.    BURTON    ON    THE    FLAGELLUM    OF    SOME    EUGLENAE. 

opposite  sides.  These  would  be  put  down  at  once  as  loops — or 
kinks — and  I  believe  the  so-called  terminal  disc  or  bulb  is  of  the 
same  nature,  but  it  is  more  striking  and  more  deceptive,  owing 
solely  to  its  position.  When  I  told  Mr.  Ellis  of  the  conclusion  I 
had  come  to,  he  was  at  first  disinclined  to  accept  it,  but  after- 
wards, I  think,  did  so  fully.  If  I  am  right,  the  subject  is  merely 
an  instance  of  correct  observation  but  incorrect  deduction  from 
it — in  fact,  an  error  of  interpretation,  quite  a  well-known  occur- 
rence to  microscopists  !  Perhaps,  indeed,  the  matter  would  hardly 
justify  particular  reference  to  it,  had  not  the  figure  and  the  note 
read  appeared  in  Saville-Kent's  Manual — a  work  whose  value  to 
us  all  gives  it  an  importance  and  authority  which  must  be  my 
excuse. 


Joura.  Que/cett  Microscopical  L'lub,  Ser.  2,  Vol.  XII  ,  A'o.  74,  April  li'14.. 


205 


ON     THE     MEASUREMENT    OF    THE     INITIAL     MAGNI 
FYING     POWERS     OF     OBJECTIVES. 

By  Edward  M.  Nelson,  F.R.M.S. 

{Read  November  25th,  1913.) 

Fig  9. 

The  majority  of  uiicroscopists  only  concern  themselves  with  the 
total  magnifying  power  of  their  microscopes,  but  some  wishing  to 
probe  further  into  matters  want  to  know  the  initial  power  of  their 
objectives. 

The  initial  magnifying  power,  m,  of  an  objective  is  -7-,  but  the 

focal  length  (f)  of  an  objective  is  a  very  difficult  thing  to  measure 
directly.     Usually  it  is  found  by  an  indirect  method  of  measuring 

the  magnifying  power,  for,  as  above,  —  =  /. 

Probably  the  best  way  of  measuring  the  focal  length  by  the 
indirect  method  is  to  project  the  image  of  a  measured  object, 
placed  100  inches  from  the  stage,  and  to  measure  the  diminished 
image  at  the  focal  point  of  the  objective  by  means  of  a  microscope, 
fitted  with  a  screw  micrometer ;  the  magnification,  m,  thus 
obtained    will    give    the    focal    length   with    great  accuracy,    for 

f  —  ~     —z.     As  the  numerator  is  100,  the  result  can  be  found  in 

nt  4-  'Ji 

a  reciprocal  table,  without  the  necessity  of  doing  a  division  sum. 

Simple  as  this  seems,  it  is  however  a  troublesome  thing  to  do  ; 
but  by  the  method  here  described  the  initial  power,  and  hence  the 


296        E.  M.  NELSON  ON  THE  MEASUREMENT  OF  THE 

equivalent  focus  of  a  microscope  objective,  can  be  quickly  and 
easily  measured. 

The  apparatus  required  is  a  stage  micrometer  and  a  screw 
micrometer  with  a  positive  eye-piece.  With  a  tube  of  a  length 
as  described  below,  the  interval  of  two  divisions  of  the  micro- 
meter scale  on  the  stage  is  read  on  the  drum  of  the  eye-piece, 
and  this  reading  will  be  the  initial  magnifying  power  of  the 
objective. 

The  only  difficulty  here  is  the  determination  of  the  proper 
tube  length.  The  tube  length  is  to  be  measured  from  the 
web  in  the  eye -piece  to  the  end  of  the  nose-piece  of  the 
microscope. 

The    formula    for   the    determination   of   the   tube   length  is 

15  \/  -  -f-  0335,  where  p  is  the  nominal  initial  power.    Example: 
V 

The  initial  power  of  a  half-inch  is  required.  The  nominal 
power  of  a  half-inch  is  20,  which  is  p,  then  15  A/ — +  0*335  = 

15v/0-385  =  15  x  0'62  =  9*3  inches  tube  length. 

The  tube  must  be  drawn  out  until  the  web  is  9-3  inches  from  the 
nose-piece,  and,  with  the  half-inch  on  the  nose-piece,  two  y^^ths 
of  an  inch  divisions  on  the  stage  micrometer  are  spanned  by  the 
webs.  The  drum  then  is  read,  say,  22*4,  and  this  is  the  initial 
power  of  that  half-inch,  without  any  further  calculation;  its  focal 

length  is  ip^  ov  Q'^Afi  inch. 

In  case  the  nominal  initial  power  is  unknown,  it  is  first  deter- 
mined with,  say,  a  9^-inch  tube,  the  value  thus  found  is  inserted 
in  the  equation  and  the  measurement  made  again  with  the 
correct  tube  length.  All  powers  of  quarter-inch  and  less  focus,  all 
Zeiss's  apochromats  of  whatever  focus,  and  other  makers'  apoch- 
romats,  require  a  9-inch  tube. 


INITIAL    MAGNIFYING    POWERS    OF    OBJECTIVES. 


297 


For  lower  powers  the  accompanying  table,  computed  by  the 
above  formula,  gives  the  necessary  tube  length. 

It  must  be  noted  that  it  has  been  assumed  that  the  screw 
micrometer  with  the  positive  eye-piece  is  an  English  one,  with 
50  threads  to  the  inch,  but  if  it  is  a  Continental  one,  with  a 
millimetre  thread,  a  millimetre  stage  micrometer  must  be  used, 
and  the  proper  number  of  divisions  measured.  If  it  is  found  that 
the  magnification  is  so  high  that  two  divisions  cannot  be  spanned 
by  the  micrometer  webs,  then  obviously  one  division  is  measured 
and  the  reading  is  doubled.* 

TABLE. 
0,  objective  ;  N,  nominal  power  ;  T,  tube  length  in  inches. 


0 

N 

T 

O 

N 

T 

o 

12-3 

1 

10 

9-9 

3 

3-5 

11-8 

3 
4 

12 

9-7 

4 

11-5 

2 
3 

15 

9-5 

4-5 

11-2 

1 
2 

20 

9-3 

2 

5 

11-0 

4 

25 

9-2 

5-5 

10-8 

1 
7J 

30 

9-1 

6 

10-6 

35 

9-05 

1| 

7 
8 
9 

10-4 
10-2 
100 

1 

40 

9-0 

Let  me  again   impress  upon   microscopists  to  measure,  or  get 
measured,  the   optical   indices  of  their  objectives.     The  optical 
1000  N.A. 


index  is 


m 


Photographers  have  the  same  thing  in  their 


//4,  //16,  etc.  No  photographer  would  think  of  paying  as  much  for 
a  lens  of  f/lQ  as  he  would  for  one,  of  similar  focus  and  qualitv,  of 
fji)  then  why  should  a  microscopist?    A  microscopist,  for  example, 

The  foci  of  a  large  number  of  all  sorts  of  microscope  objectives,  which 
had  been  previously  accurately  determined  by  the  long  method,  were 
remeasured  by  this  new  short  method ;  the  results  obtained  were  so 
satisfactory  that  now  only  the  short  method  is  used. 


298        E.  M.  NELSON  ON  THE  MEASUREMENT  OF  THE 

buys  a  T*oth  objective  of  0"65  N.A.  Here  an  optical  index  of  26-0 
is  implied ;  when  he  gets  home  he  measures  it  and  finds  it  |rd  of 
055  N.A.  with  an  optical  index  of  only  18*3,  or  30  per  cent.  less. 
This  is  not  an  exceptional  case,  but  one  which  unfortunately 
exemplifies  the  usual  practice.  Messrs.  Zeiss  have  for  long  set  an 
excellent  example  by  never  sending  out  lenses  below  either  their 
catalogued  N.A.  or  shorter  foci.  I  have  measured  scores  of  them 
and  have  found  their  optical  indices  often  in  excess,  and  seldom 
if  ever  in  defect. 

[The  method  of  determining  the  focal  length  of  an  objective, 
by  the  indirect  method  from  the  magnifying  power,  may  not  be 


A 


t 


B 


L too  inc\e& _^ 

i 


c 


Mr 


r 


s 

Fig  9. — Diagram  to  show  Relative  Positions  of  the  Apparatus. 

M — Microscope  tube.  P> — Objective. 

A — Screw  micrometer.        C — Objective  to  be  measured,  in  substage. 
S — Microscope  stage  and  micrometer. 

quite  clear,  hence  the  following  particulars  from  notes  received 
from  Mr.  Nelson  may  be  useful.  His  own  words  are  practically 
as  follows:  The  microscope  is  placed  horizontally;  a  low- power 
objective,  3,  2,  or  1|  inch,  according  to  circumstances,  is  placed 
in  position ;  screw-micrometer  eye-piece ;  the  objective  to  be  mea- 
sured is  placed  in  substage,  with  its  front  lens  facing  the  stage. 
A  card  cut  to  the  pattern  as  shown  in  figure  (fig.  9)  is  fixed  by 
means  of  a  clip  in  front  of  the  window  :  the  card  should  be 
placed  at  the  exact  measured  distance  of  one  hundred  inches 
from  the  stage  of  the  microscope. 


INITIAL    MAGNIFYING     POWERS    OF    OBJECTIVES.  209 

The  stage  micrometer  is  placed  on  the  stage,  and  the  constant 
of  the  screw-micrometer  determined.  The  focus  of  the  micro- 
scope is  not  to  be  disturbed,  but,  by  means  of  substage  focusing, 
the  lens  to  be  measured  is  racked  up  until  the  image  of  the  card 
is  sharply  focused.  Then  one  of  the  sides  of  the  card  is  spanned 
by  the  webs  of  the  eye-piece  micrometer,  and  its  size  measured 
and  the  magnifying  (or  rather  diminishing)  power  found  :   then 

._     100 
•    ~~  m  +  '2' 

Of   course,    the   idea    of  the   5  inches  is  that  the  reading  is 

doubled,  and  then  10  -t- x  (say),  gives  the  magnification,  m,  which 

can  be  found  from  reciprocal  tables,  as  well  as  the  value  of — 

^  '  1,1  +  T 

It  is  not  difficult,  but  a  little  more  trouble,  to  make  the  calcu- 
lations without  tables. 

For  the  benefit  of  photomicrographic  members,  the  following 
is  quoted  from  a  note  by  Mr.  Nelson.  "  This  method  will 
measure    the    foci   of   large   photographic   lenses.     In    that    case 

,_     100    _       100       „ 

m  +  2       (m  +  If 

"  This  second  term  is  only  necessary  when  f  is  large  compared 
with  one  hundred  inches  ;  for  microscopic  lenses  it  is  not  wanted. 
The  whole  can  be  determined  from  reciprocal  tables  without 
putting  pencil  to  paper."  The  tables  referred  to  are  those  of 
Barlow,  published  by  Messrs.  E.  &  F.  N.  Spon. 

The  screw-micrometer  eye-piece  is,  perhaps,  a  drawback.  Mr. 
Nelson  says,  "An  ordinary  screw-micrometer  with  a  negative 
eye-piece  is  no  good  for  lens  measurements ;  the  eye-piece  must  be 
of  the  Ramsden  type,  and  it  is  very  doubtful  if  any  ordinary 
ruled  glass  micrometer  eye-piece  would  be  sufficiently  accurate. 
A  screw-micrometer  is  necessary  for  both  the  methods  described 
in  the  paper." 


300     E.  M.  NELSON    ON   INITIAL  MAGNIFYING    POWERS    OF   OBJECTIVES. 

It  will  be  noticed  that  Mr.  Nelson  lays  stress  on  what  he  has 
named  the  Optical  Index ;  but  perhaps  it  is  less  apparent  that 
this  paper  on  the  magnifying  power  of  objectives,  and  his  com- 
munication to  the  last  meeting  on  their  aperture,  are  quite 
closely  related  to  the  Optical  Index — in  fact,  they  deal  with  both 
the  values  involved  in  the  formula  for  the  Optical  Index  of  an 

,  .     ..  Numerical  Aperture  x  1,000 

objective  =  — —A ^ . 

Magnifying  .rower 

A  general  way  of  expressing  the  meaning  of  the  Optical  Index 

of  an  objective  is  that   it   is  the  ratio  of    its   aperture   to   its 

power. — J.  Grundy.] 


Joura.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  74,  April  1914. 


301 


SOME  OBSERVATIONS  CONCERNING  SUB-STAGE 

ILLUMINATION. 

By  S.  C.  Akehurst,  F.R.M.S. 

(Bead  January  27th,  1914.) 

Plates  20-22. 

The  accepted  method,  and  the  one  generally  used,  for  sub-stage 
illumination  is  that  known  as  the  solid  cone  of  light,  controlled, 
within  certain  limits,  by  the  iris  diaphragm.  Another  form — that 
is,  annular  light — is  occasionally  used,  but  is  not  considered  by 
many  microseopists  to  be  of  value  for  critical  work. 

Both  these  forms  of  illumination  are  too  well  known  to  need 
detailed  explanation.  The  textbooks,  however,  have  very  little 
to  say  either  for  or  against  the  latter  method,  excepting  Cross  and 
Cole,  3rd  edition,  where  a  definite  statement  in  favour  of  annular 
light  is  to  be  found.  I  cannot  do  better  than  quote  this  :  "  Stops 
can  be  further  used  for  strengthening  the  contrast  in  the  image 
with  large  cones  of  illumination  and  objectives  having  high 
apertures.  This  method  does  not  minimise  in  any  way  the 
effective  working  of  the  objective,  for,  with  objectives  of  large 
aperture,  rays  may  be  present  which  only  impart  brightness  to 
the  field,  but  do  not  contribute  to  making  visible  the  fine  detail 
upon  the  object.  If  less  than  half  of  the  lateral  spectra  are  seen 
on  looking  down  the  tube  at  the  back  lens  of  the  object  glass  with 
a  striated  object  in  focus,  then  the  central  portion  of  the  direct 
beam  or  central  disc  has  no  lateral  image  corresponding  to  it  in 
the  portions  of  the  spectra  that  are  visible.  Under  these  circum- 
stances, that  central  portion  of  the  central  disc  in  no  degree 
contributes  in  enabling  the  detail  to  be  seen,  but  only  produces  a 
haze ;  by  blocking  it  out  the  haze  is  removed  and  there  is  a  great 


302         S.    C.    AKEHURST    ON    SOME    OBSERVATIONS    CONCERNING 

improvement  in  the  resulting  definition."  Mr.  J.  W.  Gordon's 
opinion  is  that  when  a  suitable  stop  is  employed  in  the  sub-stage 
condenser  there  is  no  objection  to  using  annular  light  with  an  oil- 
imniersion  objective  of  high  numerical  aperture.  It  is,  however, 
necessary  that  the  outer  zones  of  the  objective  used  should  be 
well  corrected.  His  own  method  of  blocking  out  the  central 
beam  is  to  use  a  stop  over  the  eye-piece — and  this  is  fully  described 
in  the  Journal  R.  M.  S.,  February  1907.  On  the  other  hand, 
Carpenter  does  not  entirely  agree  that  annular  light  is  permissible. 
Quoting  from  the  seventh  edition,  he  says,  "  If  it  is  required  to 
accentuate  a  known  structure,  such  as  the  perforated  membrane  of 
a  diatom,  it  can  be  done  by  annular  illumination,  which  means 
the  same  arrangement  as  for  dark-ground  but  with  a  stop  insuffi- 
ciently large  to  shut  out  all  the  light.  This  method  is  not  to  be 
recommended  when  a  structure  is  unknown,  as  it  is  also  liable  to 
give  false  images." 

Mr.  Nelson  has  also  expressed  himself  against  annular  light, 
stating  that  whilst  strong  resolution  of  diatoms  is  obtained  by 
this  method  of  illumination  it  also  gives  rise  to  spurious  images. 

The  subject  of  sub-stage  illumination  is  a  large  one,  and  I  am 
only  dealing  with  one  phase  of  it,  viz.  annular  light  produced  by 
a  reflecting  condenser,  to  be  used  in  conjunction  with  an  oil- 
immersion  objective,  for  resolving  the  fine  structure  of  diatoms 
and  displaying  stained  bacteria.*  When  a  wide-angle  refracting 
condenser  is  employed,  with  stop  to  produce  annular  light,  trouble 
arises  through  chromatic  aberration,  which  is  especially  noticeable 
when  an  objective  of  high  aperture  is  used.  This  dispersed  colour 
is  objectionable,  as  it  operates  against  a  pure  image  being  formed, 
and  is  also  detrimental  to  obtaining  faithful  records  by  photo- 
graphy. Much  has  been  undertaken  to  demonstrate  that,  in 
practice,  light  from  a  condenser  exhibiting  chromatic  aberration 

*  A  slide  of  Tubercle  bacilli  was  exhibited  illuminated  with  annular 
light,  showing  that  the  reflecting  condenser  works  well  with  small  stained 
objects  in  addition  to  diatoms. 


SUB-STAGE    ILLUMINATION.  303 

does  not  prevent  good  work  being  accomplished.  On  the  other 
hand,  I  believe  the  reduction  of  chromatic  dispersion  to  a  minimum 
leads  towards  an  ideal  system  for  critical  work. 

The  question  now  arises,  if  annular  light  is  employed  with 
objectives  of  high  aperture,  how  is  the  trouble  arising  through 
chromatic  aberration  to  be  avoided.  I  suggest  reflected,  instead 
of  refracted,  light  being  used.  I  came  to  this  conclusion  after 
makincr  a  number  of  observations  with  a  Leitz  concentric  reflect- 
ing  condenser.  This  condenser  has  two  reflecting  surfaces,  one 
convex  and  the  other  concave,  and,  as  the  rays  are  brought  to  a 
focus  by  reflection  only,  there  is  no  chromatic  dispersion,  and 
spherical  aberration  is  reduced  to  a  minimum.  The  elimination 
of  spherical  aberration,  however,  is  not  a  matter  of  importance. 
This  was  pointed  out  to  me  by  Mr.  J.  W.  Gordon,  who  has  very 
generously  allowed  me  to  make  use  of  his  remarks  on  this  point. 

He  says:  "Light  from  the  periphery  of  the  condenser  may 
exhibit  defects  due  to  spherical  aberration.  This  light,  on  reach- 
ing the  object,  sets  up  a  new  impulse,  and  the  rays  emerging  from 
the  object,  and  travelling  towards  the  eye,  will,  in  any  plane  con- 
jugate to  the  plane  of  the  stage,  appear  free  from  the  original 
defects  of  spherical  aberration — just  as  if  they  had  started  from 
an  independent  source.  No  false  images  would,  therefore,  arise 
from  this  cause  in  the  image  plane  when  light  is  used  from  a 
sub-stage  condenser  that  has  not  been  corrected  for  spherical 
-aberration."  It  should  be  carefully  noted  that  this  reflecting  con- 
denser was  produced  to  obtain  dark-ground  effects,  and  was  never 
intended  to  be  used  in  the  manner  I  have  employed  it — that  is,  in 
conjunction  with  a  TV  inch  oil-immersion  objective  without  a  funnel 
stop  to  reduce  the  IS".  A.  of  the  objective.  In  its  present  form  the 
reflecting  condenser  I  have  passes  too  much  light.  The  results 
obtained,  however,  were  sufficiently  striking  to  arrest  attention 
when  resolving  fine  structure  of  various  diatoms.  The  transverse 
striae  of  Amphlpleura  pellucida  in  monobromide  of  naphthalin 
were  displayed.    In  realgar  the  same  details  were  strongly  shown, 


304         S.    C.    AKEHURST    OX    SOME    OBSERVATIONS    CONCERNING 

and  when  the  mirror  was  slightly  tilted,  if  the  diatom  was  a 
suitable  one.  it  was  resolved  into  dots.  A  good  image  of  the 
rosettes  on  Coscinodiscus  asteromphcdus  was  obtained,  which 
stood  a  high-power  eve-piece  well.  With  the  mirror  slightly 
tilted,  the  faintly  marked  transverse  striae  were  visible  on  Cymato- 
pleura  solea — also  an  excellent  black-dot  image  was  displayed  of 
Xo.ck'da  rhomboid.es,  SurireUa  gemma  and  Pleurosigma  angu- 
IcUuin.  On  examining  a  strewn  slide  of  Xacicula  r~homboid.es 
in  realgar  I  found  a  specimen  of  Pinnularia  nobilisl  On  tilting 
the  mirror  and  obtaining  oblique  light  the  costae  were  filled  with 
dots.  Particulars  of  this  were  forwarded  to  Mr.  Nelson,  who 
replied  as  follows:  "Mr.  Merlin  and  I  have  seen  the  structure 
on  Pinnularia  to  which  you  refer.  It  was  demonstrated  upwards 
of  twenty  years  ago  by  H.  Gill,  who  tilled  up  the  apertures  in 
diatoms  with  platinum — some  of  these  specimens  I  have  still."  I 
am  pleased  to  be  able  to  give  this  report,  as  it  helps  to  dispose  of 
the  idea  that  might  arise  that  the  dots  displayed  were  probably 
due  to  false  images,  brought  about  by  using  annular  light. 

The  opaque  lines  on  an  Abbe  test  plate  were  well  defined,  and 
an  excellent  rendering  of  stained  bacteria,  such  as  Tubercle  bacilli,, 
was  obtained.  In  all  the  tests  referred  to  the  following  combina- 
tion was  used  :  Incandescent  gaslight,  Nelson  stand  condenser, 
Leitz  concentric  reflecting  condenser  and  tiuorite,  TVth  inch  oil- 
immersiun  objective  N.A.  1*35,  Wiukel  complanat  eye-piece,  and 
Wratten  B  screen. 

During  the  autumn  of  1913  Mr.  O'Donohoe  became  interested 

in  this  reflecting  condenser,   and  he  spent   an  evening  with  me 

examining  some  of  the  test  objects  referred  to  ;  and  afterwards 

kindly  undertook  to  see  if  any  results  worth  attention  could  be 

obtained  by  photography  when  using  this  type  of  condenser.     He 

was  successful  in  getting  a  record  of  the  dots  on  Pinnularia.* 

I  am  very  much  indebted  to  Mr.  O'Donohoe  for  the  ready 
manner  in  which  he  undertook  the  work  of  testing  the  condenser, 

*  T.  A.  O'Donohoe  :  "An  Attempt  to  Resolve  Pinnularia  xobilis,''  p.  309. 


SUB-STAGE    ILLUMINATION.  305 

and  for  the  photographs  which  illustrate  this  paper ;  and  you 
will  agree  with  me  that  without  these  records  my  remarks  con- 
cerning the  value  of  reflected  annular  illumination  would  have 
been  much  less  convincing. 

Summary  of  the  Advantages  in  using  Annular  Light 
produced  by  reflecting  condenser. 

(1)  When  employing  an  achromatic  condenser  excess  of  light 
is  reduced  by  closing  the  iris  diaphragm.  This  involves  a  sacrifice 
of  the  numerical  aperture,  and,  therefore,  loss  of  resolution. 
With  the  reflecting  concentric  condenser  there  is  no  loss  of  high- 
angle  rays,  the  excess  of  light  being  modified  by  stopping  out  a 
portion  of  the  central  or  dioptric  beam;  the  fullest  possible 
advantage  can,  therefore,  be  taken  of  the  numerical  aperture  of 
the  whole  optical  system. 

(2)  Chromatic  dispersion  being  entirely  eliminated,  a  pure 
image  is  obtained. 

(3)  The  absence  of  colour  in  the  field  admits  of  critical  work 
being  done  by  photo-micrography. 

(4)  When  necessity  arises  to  search  a  slide  for  minute  striae, 
or  other  fine  structure,  it  is  immaterial  in  which  direction  across 
the  field  the  striae  appear — they  are  resolved. 

(5)  The  simple  construction  of  this  type  of  condenser  admits 
of  it  being  produced  at  about  half  the  cost  of  an  achromatic  oil- 
immersion  condenser ;  and  whilst  it  can  only  be  employed  with  a 
Y2-th  inch  oil-immersion  objective  in  the  manner  already  described, 
yet  it  gives  excellent  dark-ground  effects  with  all  powers  from 
Ygth  to  ^th  inch. 

One  defect — if  defect  it  can  be  called — is  that,  in  its  present 
form,  there  is  no  method  of  controlling  the  light  passed  by  altering 
the  size  of  the  stop.  It  is  just  possible  means  can  be  devised  to 
allow  of  this  being  done. 

In  my  opinion  there  appears  to  be  room  for  a  reflecting  con- 


306  S.    C.    AKEHURST    ON    SOME    OBSERVATIONS    CONCERNING 

denser  to  be  used  with  high-angled  oil-immersion  objectives,  even 
though  the  field  for  its  usefulness  may  be  limited. 

1  hope  the  photographs  illustrating  this  paper  will  prove  of 
sufficient  interest  to  stimulate  further  investigation  into  the 
value  of  annular  light,  and  to  demonstrate  what  limits,  if  any, 
should  be  put  upon  its  use. 

Descriptions  of  Plates. 
Plate  20. 

Figs.  1  to  7  are  illustrations  of  various  figures  of  the  spectra 
of  Pleurosigma  angulatum  as  seen  at  the  back  lens  of  an  oil- 
immersion  objective  with  the  diatom  in  focus — an  achromatic 
condenser,  with  and  without  stop,  and  reflecting  condenser  being 
used.  Pigs.  1  to  3  are  of  no  special  interest  just  now — most  of 
you  are  familiar  with  these  diffraction  spectra,  varied  according 
to  the  diameter  of  the  opening  in  the  iris  diaphragm. 

Fig.  1  shows  result  obtained  with  the  diaphragm  almost  closed. 

Fig.  2  the  diaphragm  is  opened  so  that  one-third  of  the  back 
lens  is  in  shadow.  The  details  of  the  diatom  are  hardl)T  per- 
ceptible, being  flooded  out  by  excess  of  light. 

Fig.  3.  The  iris  is  closed,  until  two-thirds  of  back  lens  is  in 
shadow.  In  this  position,  with  the  spectra  just  touching  the 
edge  of  the  central  beam  of  light,  the  best  resolution  of  Pleuro- 
sigma angulatum  is  obtained. 

Fig.  4  shows  the  spectra  obtained  when  a  large  spot  is  used. 
The  six  diffraction  spectra  forming  the  symmetrical  image  should, 
however,  be  slightly  moved  from  the  centre  outwards  to  reduce 
the  diameter  of  the  hexagonal  spot  in  the  centre,  which  in  the 
drawing  is  a  little  too  large.  In  this  instance  insufficient  light 
was  passed,  and  an  unsatisfactory  image  of  the  diatom  was  dis- 
played. My  next  spot  being  too  small,  the  picture  of  the  spectra 
obtained  is  as  shown  by  flg.  5.  Here  Ave  have  six  dark  cuspidate 
forms,  disposed  as  a  six-pointed  star,  the  intermediate  spaces 
being  filled  with  a  diffused  light,  the  whole  figure  being  some- 


SUB-STAGE    ILLUMINATION.  307 

what  ill-defined.  This  effect  was  due  to  an  excess  of  light ;  by 
slightly  closing  the  iris  diaphragm  the  light  was  reduced,  and  we 
have  the  result  as  shown  in  fig.  6 — the  symmetrical  design  well 
defined  on  a  black  ground,  and  just  a  glimpse  of  another  portion 
of  the  spectra  at  six  points  round  the  shadow  caused  by  the  partly 
closed  diaphragm.  With  the  spectra  showing,  as  illustrated  in 
fig.  6,  I  obtained  the  best  definition  of  Phurosiyma  angulatum 
with  achromatic  condenser  and  spot. 

Fig.  7  is  the  record  of  the  spectra  obtained  of  the  same  diatom, 
using  the  reflecting  condenser  ;  the  similarity  between  the  figures 
7  and  5  is  noticeable. 

My  reflecting  condenser — to  work  at  its  best  when  using  it  for 
annular  light — requires  the  light  cut  down  until  a  crisp  image  is 
shown  of  the  spectra  as  at  fig.  6. 

Fig.  8  represents  the  rulings  on  an  Abbe  test  plate,  as  displayed 
by  TV  inch  oil-immersion  objective  and  reflecting  condenser.  The 
position  of  the  light  bars  is  to  be  noted  :  there  are  six — those  at 
the  top  and  bottom  are  not  quite  fully  displayed.  On  first 
examining  the  back  of  the  objective  I  observed  the  two  rows 
of  six  white  dots,  as  shown  at  fig.  9.  At  another  examination — 
the  light  probably  being  more  central — I  found  an  almost  com- 
plete circle,  as  at  fig.  10,  made  up  of  ten  white  clots  on  each  side 
and  a  thin  streak  of  light  at  the  bottom.  I  have  not  yet  been 
able  to  put  forward  a  suggestion  as  to  how  these  are  formed. 
I  have,  however,  included  them  in  my  record,  as  they  may  be 
of  some  interest. 

Plate  21. 

Fig.  1.  Nitzschia  linearis  x  2,500,  showing  the  white-dot  image. 
This  photograph  was  taken  with  a  highly  corrected  oil-immersion 
condenser  and  axial  illumination. 

Fig.  2.  Nitzschia  linearis  x  3,000,  this  time  showing  the 
black-dot  image.  This  photograph  was  taken  with  reflecting 
concentric  condenser. 

Journ.  Q.  M.  C,  Series  II.— No.  74.  22 


308  S.    C.    AKEHURST    ON    SUB-STAGE    ILLUMINATION. 

Both  these  pictures  were  taken  by  the  same  man,  using  the 
same  objective,  diatom  and  illumination — the  only  difference 
being  in  the  condenser  used.  Regarding  this  matter,  Mr. 
O'Donohoe  writes  as  follows  :  "  I  was  never  able  to  see  the 
black-dot  image  when  using  my  ordinary  oil-immersion  condenser, 
hence  was  much  surprised  to  find  that  the  reflecting  concentric 
condenser  showed  the  black  dots  beautifully.  This  and  the 
Amphipleura  show  that  the  reflecting  condenser  is  a  better  re- 
solver  than  my  ordinary  oil-immersion  condenser  and  axial 
illumination. 

Fig.  3.  Amphipleura  pellucida  x  2,000.  This  photograph  was 
taken  to  demonstrate  the  usefulness  of  annular  light  when 
searching  a  slide  for  fine  structure.  The  diatoms  are  at  right 
angles  to  each  other,  and  both  resolved.  Had  light  in  one 
azimuth  been  employed,  such  as  one  gets  with  an  achromatic 
condenser,  and  quarter-moon  stop,  only  one  would  have  been 
resolved,  viz.  the  diatom  with  striae  at  right  angles  to  the 
direction  of  the  beam  of  light. 

Fig.  4.  A  record  of  Surirella  gemma  x  2,000.  This  was 
taken  with  the  reflecting  condenser.  The  black  dot  is  shown, 
and  at  the  same  time  the  ribs  are  resolved  into  dots. 

Plate  22. 

Fig.  1.  Navicida  rkomboides  x  1,500,  taken  with  the  re- 
flecting condenser. 

Fig.  2.  Pinnidaria  nobdis  x  2,500,  showing  the  costae  filled 
with  dots.     Taken  with  the  reflecting  condenser. 


Journ.  Quekett  Microscopical  Club,  Scr.  2,  Vol.  XII.,  No.  74,  April  1914. 


Journ.   O.M.C. 


Ser.  2,  Vol.  XII.,  PI.  20. 


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Journ.  Q.M.C. 


Ser.  2,  Vol.  XII.,   PL   21. 


T.  A.  O'Donohoe,  photogr. 

Resolution  with  Annular  Illumination. 


Journ.   Q.M.C. 


Sen  2,  Vol.  XII.,   PL  22. 


T.  A.  O'Donohoe,  phologr. 

Resolution  with  Annular  Illumination. 


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09 


AN   ATTEMPT   TO    RESOLVE   AND    PHOTOGRAPH 

PINNULARIA    NOB  I  US. 

By  T.  A.  O'Doxohoe. 

(Read  January  21th,  1914.) 

Most  microscopists  are  acquainted  with  the  little  diatom  called 
Pinnidaria  nobilis,  which,  on  the  test  slides  of  twenty  diatoms 
mounted  by  Moller  and  Thum,  takes  the  second  lowest  place, 
with  striae  numbering  from  11,000  to  12,000  to  the  inch. 
It  is  just  because  it  occupies  such  a  lowly  place  that  it  is 
passed  over  with  contempt  as  being  worthy  of  the  notice  only 
of  the  babes  and  sucklings  of  microscopy  who  find  themselves 
in  possession  of  a  2-inch  or  1-inch  objective. 

Such  was  my  own  feeling  towards  it  until  quite  recently, 
when  Mr.  Akehurst  showed  me  by  resolution  into  dots  that  it 
deserved  a  better  fate,  and  invited  me  to  resolve  and  photograph 
it,  if  I  could,  and  for  this  purpose  he,  at  the  same  time,  lent 
me  a  realgar  mount  and  the  reflecting  dark-ground  condenser 
of  Leitz.  I  have  since  learnt  that  an  objective  and  illumination 
which,  without  any  manipulation,  showed  me  at  once  the  striae  of 
Nitzschia  linearis,  Frustulia  saxonica,  and  Amphiplewa  pellucida, 
and  the  very  distinct  black  dots  of  all  the  other  diatoms  on 
Thum's  test  plate  of  30  forms,  failed  completely  in  inducing  the 
Pinnidaria  nobilis  on  the  same  slide  to  yield  up  its  secrets.  So 
that  the  diatom  to  which  almost  the  lowest  place  is  assigned 
by  the  mounter  is,  in  fact,  by  far  the  most  difficult  to  resolve. 
Examined  with  a  drv  lens  of  N.A.  0-85  and  direct  cone  of 
light,  we  get  an  image  in  which  on  each  side  of  the  raphe 
are  seen  two  zig-zag  lines  running  from  end  to  end  and  dividing 
the  linger-like  bands  into  three  series — or  each  band  into  three 
compartments.     This  is  all  that  can  be  seen  with  a  dry  lens. 

Now  using  a  Zeiss  2-mm.  apochromat  N.A.  1*3,  and  Watson's 
Holoscopic  immersion  condenser,  and  finding  a  central  cone  of 
light  unavailing,  I  inserted  the  crescent  stop  in  the  condenser, 
and  proceeding  as  if  I  were  resolving  the  striae  of  Amphiphura 
pellucida,  I  succeeded  in  getting  an  image  which  shows  what  one 


310  T.  a.  o'doxohoe  on  pin  nul  aria  nobilis. 

must  call  the  costae,  broken  up  into  three  parts,  with  very  fine 
lines  between  them.  It  may  be  seen  that  the  middle  parts  of 
the  costae  are  in  the  sharpest  focus  because  they  represent  the 
highest  of  three  distinct  planes.  Now  if  this  interpretation  be 
correct,  the  structure  of  this  diatom  is  very  complex,  as  there 
would  be  three  planes  on  each  side  of  the  raphe,  and  the  planes 
on  the  one  side  would  coincide  with  those  on  the  other  only  when 
the  diatom  was  perfectly  flat  on  the  cover-glass  —a  very  un- 
likely case. 

I  now  tried  to  resolve  the  costae,  with  the  result  as  shown 
[here  an  image  was  projected  on  the  screen],  which  reminds  one 
of  the  bones  of  a  skeleton's  hand. 

There  remained  the  resolution  of  the  very  fine  lines  between 
the  costae,  probably  into  dots.  After  trying  to  do  this  many 
hours  without  any  success  I  substituted  Mr.  Akehurst's  dark- 
ground  condenser  for  the  Holoscopic,  with  the  result  that,  after 
considerable  manipulation  I  was  able  to  get  the  photograph  here 
reproduced.  (See  PI.  22,  fig.  2.)  This  shows  at  least  partial 
resolution  on  both  sides  of  the  raphe. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  74,  April  1914. 


311 


NOTES. 

ON    A    METHOD    OF    MARKING  A  GIVEN    OBJECT    FOR 
FUTURE    REFERENCE    ON   A    MOUNTED   SLIDE. 

By  James  Burton. 

{Read  November  25th,  1913.) 

Most  likely  all  of  us  at  times  have  come  across  some  particular 
object  on  a  mounted  slide  which  we  have  felt  we  should  like  to  be 
able  to  find  on  another  occasion ;  perhaps  some  special  diatom  on 
a  strewn  slide,  for  instance.  Now  there  are  several  methods  of 
doing  this,  and  a  little  piece  of  apparatus  is  sold  by  the  opticians 
which  marks  a  circle  round  an  object  first  found  under  the  micro- 
scope. But  perhaps  with  the  majority  the  necessity  does  not 
occur  often  enough  for  it  to  be  worth  while  to  keep  a  special  tool, 
and  the  little  dodge,  if  I  may  call  it  so,  which  is  here  described 
can  be  carried  out  without  any  other  instrument  than  those  we 
most  of  us  already  have  and  use.  If  the  object  to  be  marked  is 
sufficiently  large  for  recognition  under  a  moderate  power,  such  as 
can  be  obtained  with  a  hand  lens  or  dissecting  microscope,  the 
matter  is  very  simple.  First  find  the  object,  then  with  a  fine 
camel-hair  or  sable  brush  carefully  place  a  dot  of  water-colour 
over  it  large  enough  to  be  seen  with  the  naked  eye,  set  it  on  one 
side  to  dry ;  when  dry,  put  the  slide  on  the  turn-table  with  the 
dot  accurately  in  the  centre  and  turn  a  small  ring  round  it  with 
any  dark  cement  you  may  have  in  use;  when  this  is  hard,  which 
will  depend  on  the  kind  of  cement  used,  the  water-colour  can  be 
removed  with  a  damp  brush,  and  the  cover  can  be  carefully 
cleaned  with  a  piece  of  soft  rag. 

If  the  object,  however,  is  too  small  to  be  readily  recognised 
without  a  high  power,  as,  of  course,  is  usually  the  case,  for 
it  is  not  necessary  to  mark  anything  but  minute  objects, 
a  rather  more  complicated  variety  of  the  same  plan  should 
be  adopted.  Again  first  find  the  object  with  a  suitable 
power,  such  as  a  |  inch  or  ^th  inch,  and  let  the  specimen  be  as 


312       J.    BURTON    ON    A    METHOD    OF    MARKING    A    GIVEN    OBJECT. 

accurately  placed  in  the  centre  of  the  field  as  possible  ;  then  sub- 
stitute for  this  power,  preferably  a  water- immersion  objective, 
say  TV^h,  put  on  the  front  lens  a  small  drop  of  water  and  care- 
fully focus.  It  is  necessary  that  the  slide  should  not  be  moved 
after  contact  is  made,  as  it  is  desirable  to  keep  the  drop  of  water 
as  small  as  possible.  When  the  object  is  recognised  and  is  in  the 
centre  of  the  field,  raise  the  microscope  tube  rather  sharply  and  a 
small  circular  spot  of  water  will  be  left  on  the  cover-glass  right 
over  the  desired  place.  Now  stain  this  spot  with  water-colour  as 
in  the  other  case — 1  always  use  the  carmine  kept  for  feeding 
infusoria,  etc.,  but  any  colour  will  do.  When  this  is  dry  the 
slide  may  be  roughly  examined  and  the  object  will  be  seen 
through  the  coat  of  colour,  which  for  this  purpose  should  not  be 
too  thick.  If  it  be  rightly  placed,  proceed  as  before,  putting  a 
fine  ring  of  suitable  size  round  the  spot  with  some  dark  cement, 
and  when  this  is  dry  carefully  clean  off  the  colour,  and  the 
arrangement  is  complete.  Water-immersion  lenses  are  not  very 
commonly  used  now,  and  if  the  microscopist  does  not  happen  to 
possess  one,  an  oil-immersion  may  be  used  instead,  but  obviously 
it  must  be  used  with  water,  not  oil ;  but  this  will  give  a  sufficiently 
good  image  for  our  purpose,  which  is  merely  to  recognise  the 
specimen  for  marking,  not  to  examine  it.  If  an  oil-immersion  be 
not  available,  any  close- working  objective,  say  gth  inch  or  even 
-g-th  inch  may  be  used,  but  it  is  necessary  that  the  front  lens  be  a 
small  one,  so  that  the  spot  of  water  placed  by  it  should  be  as 
local  as  possible. 

There  are,  of  course,  some  difficulties  ;  the  chief  is,  that  objects 
mounted  in  glycerine — as  mine  usually  are — are  somewhat 
liable  to  move  if  at  all  roughly  handled,  and  may  work 
out  of  the  circle  ;  but  with  balsam  or  glycerine  jelly  mounts,  or 
even  a  shallow  glycerine  one,  there  is  little  danger  of  this.  If  a 
turn-table  is  not  in  the  outfit  of  the  experimenter,  a  sufficiently 
good  circle  may  be  drawn  by  hand,  or  a  line  drawn  to  indicate 
the  position,  or,  as  has  been  suggested,  the  barrel  of  a  mapping 
pen  or  similar  object  may  be  used.  But  the  first  great  difficulty 
is  always  to  indicate  the  exact  spot  it  is  desired  to  mark,  particu- 
larly if  the  object  is  a  very  minute  one,  and  that  is  got  over  with 
facility  by  the  method  indicated. 


M.  DRAPER,  A   LIVE    BOX    FOR    THE    OBSERVATION    OF   INSECTS.     313 

A   LIVE   BOX    FOR   THE   OBSERVATION   OF   INSECTS 

AND   SIMILAR   OBJECTS. 

By  B.  M.  Draper. 

{Read  December  23rd,  1(J13.) 

This  live  box,  which  was  worked  out  for  me  by  Mr.  Angus, 
displays  satisfactorily,  with  superstage  illumination,  under  the 
lowest  powers,  large  creatures  such  as  house-flies.  It  is  not 
meant  for  pond-life. 

It  is  of  the  simplest  description,  being  really  nothing  but  a 
transparent  chamber  of  the  shape  and  size  of  a  small  pill-box. 
The  body  is  made  of  a  short  piecs  of  glass  tube  of  any  size  de- 
sired, say,  one-third  of  an  inch  deep  by  two-thirds  in  diameter  ; 
this  is  cemented  to  a  3  X  1-inch  slip.  The  lid,  which  is  loose, 
is  a  circular  plate  of  glass  of  rather  larger  diameter  than  the 
body.  In  the  lid,  near  its  circumference,  and  at  equal  distances 
from  each  other,  are  fixed  three  short  pins,  projecting  downwards, 
so  as  to  clasp  the  outside  of  the  body  and  thus  keep  the  lid  in 
position.  The  little  collars  by  which  the  pins  are  fixed  in  the 
lid  rest  on  the  rim  of  the  box,  so  as  to  prevent  the  lid  itself 
from  touching.  The  crack  thus  left  gives  enough  ventilation. 
The  depth  of  the  box  can  be  varied  by  means  of  a  false  bottom, 
preferably  opaque. 

This  box  serves  well  for  the  exhibition  of  a  fly  in  the  act  of 
feeding.  If  a  little  syrup  is  put  on  the  inside  of  the  lid  of  the 
box,  the  sucking  surface  of  the  proboscis  may  be  seen  in  action. 


DARK-GROUND  ILLUMINATION  WITH  THE  GREEN- 
HOUGH  BINOCULAR. 

By  B.  M.  Draper. 

{Bead  December  23rd,  1913.) 

The  Greenhough  pattern  of  binocular  consists,  as  is  well  known, 
of  two  separate  microscopes,  one  for  each  eye,  with  paired 
objectives  of  very  low  power.  Like  other  binoculars,  it  is 
particularly  well  suited  for  use  with  dark-ground  illumination, 
and  a  good  way  of  getting  the  dark  ground  with  its  higher 
powers  is  to  put  a  stop  behind  the  condenser. 


314  B.    M.    DRAPER    ON    THE    GREENHOUGH    BINOCULAR. 

As,  however,  the  front  lenses  of  the  twin  objectives  stand  out 
some  distance  on  either  side  of  what  would  be  the  optic  axis  of  an 
ordinary  microscope,  the  stop  has  to  be  correspondingly  broad 
from  side  to  side  ;  otherwise  direct  rays  would  enter  the  objectives 
and  would  spoil  the  dark  ground  at  the  sides  of  the  field.  But  it 
is  not  necessary  that  the  rectangular  diameters  of  the  stop  should 
be  equally  great  ;  on  the  contrary,  if  an  ordinary  circular  stop  be 
used,  some  rays  are  needlessly  obstructed.  On  trial,  a  double 
or  twin  stop,  corresponding  with  the  twin  objectives,  gave  much 
better  results.  This  stop  consists  of  two  small  circular  patches 
placed  side  by  side  in  the  same  plane,  and  touching  each  other r 
so  as  to  form  a  figure  of  eight.  It  is  used  behind  the  condenser 
in  the  same  way  as  an  ordinary  circular  stop,  and  with  almost 
equal  ease.  It  is  only  necessary  to  be  careful  that  the  two  circular 
jDatches  shall  be  placed  horizontally,  i.e.  so  as  to  be  opposite  the 
two  front  lenses  of  the  twin  objectives.  This  position  can  easily 
be  secured  by  arranging  the  stop  in  the  carrier  approximately  and 
then,  whilst  watching  the  object,  shifting  the  whole  condenser 
round  in  its  sleeve  until  the  best  effect  is  obtained.  A  standard 
low-power  condenser  such  as  Swift's  "  Paragon,"  with  its  top  lens 
off,  gives  very  satisfactory  results.  The  twin  and  the  ordinary 
circular  patterns  of  stop  were  compared  experimentally  by  using  a 
condenser  fitted  with  two  stop  carriers,  one  behind  the  other,  so 
that  either  stop  could  be  used  separately,  or  both  together.  The 
twin  stop  used  by  itself  gave  a  good  dark  ground.  The  circular 
stop  was  purposely  chosen  too  small  to  give  a  good  dark  ground  ; 
there  was  light  at  the  sides  of  the  field.  Nevertheless  when  the 
circular  stop  was  turned  in  above  the  twin  stop  whilst  the  object 
was  under  observation,  there  was  a  marked  drop  in  the  brightness 
of  the  image.  This  loss  of  light  was  due  almost  entirely  to  the 
circular  stop,  not  to  the  clear  white  glass  on  which  it  was  mounted, 
since  it  was  found  that  the  interposition  of  such  a.  piece  of  glass,, 
even  when  rather  dirty,  made  very  little  difference  to  the  light. 
Evidently,  therefore,  the  circular  stop,  though  too  small  in  one 
direction,  was  too  large  in  the  other,  and  kept  out  some  rays 
which  might  safely  have  been  admitted.  Of  course  if  the  circular 
stop  had  been  large  enough  to  darken  the  background  when 
used  by  itself,  the  loss  of  light  would  have  been  still  more 
noticeable. 


E.    M.    NELSON    ON    AMPHIPLEURA   LINDHEIMERI.  315 

AMPHIPLEURA   LINDHEIMERI. 

By  Edward  M.  Nelson,  F.R.M.S. 

(itearf  December  23rd,  1913.) 

Half  a  century  ago  Xavicula  rhomboides  was  the  accredited  test 
for  the  best  microscope  lenses.  This  was  the  common  "  English  " 
rhomboides,  which  has  about  72,000  to  73,000  striae  per  inch  ;  it 
was  also  known  as  the  Amician  test.  About  the  seventies 
iV.  rhomboides  was  discovered  in  America.  This  was  a  coarser 
form,  having  some  60,000  striae  per  inch,  consequently  any  90° 
|  inch  N.A.  0*71  would  resolve  it  readily.  In  those  days  there 
were  no  cheap  apertometers  to  be  had,  so  testing  an  objective 
merely  meant  a  measurement  of  aperture  by  resolving  striae 
on  some  diatom  by  means  of  oblique  light  in  one  azimuth.  We 
now  know  that  the  feat  can  be  accomplished  by  a  very  badly 
corrected  objective. 

The  new  coarse  American  rhomboides  became  very  popular,  and 
diatom  dotters  and  brassey  glassites  simply  revelled  in  it. 

History  has,  however,  repeated  itself,  for  as  time  went  on  lenses 
improved,  and  both  the  coarse  and  fine  rhomboides  failed  as  tests 
for  high  powers,  so  others  had  to  be  found  to  fill  their  place. 
Amphipleura  pellucida  became  the  test  for  immersions,  while 
A.  Lindheimeri  was  used  for  dry  lenses.  As  A.  Lindheimeri  has 
about  7  ",000  striae  per  inch,  it  is  a  very  suitable  test,  with  oblique 
light  from  a  dry  condenser,  for  lenses  of  the  7a  type. 

This  wTas  the  favourite  test  of  the  late  Lewis  Wright,  who 
mentions  it  in  his  excellent  book  on  the  Microscope.  But  now 
another  Lindheimeri  has  been  discovered  in  Spain,  and  as  it  is  a 
coarser  variety,  it  is  necessary  to  distinguish  between  these  forms 
when  quoting  the  Lindheimeri  as  a  test.  The  new  Lindheimeri 
has  67,000  striae  per  inch,  and  therefoi  e  is  easier  to  resolve  than 
the  old  English  rhomboides  ;  a  |  inch,  or  8  mm.,  will  very  nearly 
resolve  it — in  fact,  they  do  so  in  patches;  a  Powell  100°  |  inch 
of  1S75,  which  would  fail  on  an  English  rhomboides,  resolves  it 
easily. 

The  new  Lindheimeri  can  be  recognised  at  once  by  its  very  long 
terminal  nodules,  the  terminal  nodule  being  one-third  of  the  whole 
length  of   the  valve,   while  in  the  old  form  it  is  only  one-fifth. 


316  E.    M.    NELSON    ON    AMPHIPLEURA   LINDHEIMERI. 

The  length-breadth  ratio  in  the  new  form  is  7*5,  and  in  the 
old  8-5. 

The  conditions  here  are  therefore  opposite  to  those  we  found  in 
Naviada  rhomboides,*  for  those  with  the  greater  ratio  had  the 
coarser  striae,  but  in  this  case  they  have  the  finer. 

If  we  divide  the  ratio  by  the  number  of  striae  in  T— ff ^th  of  an 
inch  we  shall  obtain  a  numerical  index  of  about  1*1.     Thus  : 

Old  Lindheimeri  :  Ratio  8*5,  striae  7*7,  index  l'l. 

New  Lindheimeri :  Ratio  7 '5,  striae  6*7,  index  l'l 2. 

Amphipleura  pellmida  follows  much  the  same  rule,for  "resolvers" 
who  understood  the  subject  sought  out  wide  valves,  i.e.  those  with 
a  small  ratio. 

*  Journal  Q.M.C.,  vol.  xi.  p.  97,  1910. 


Jovrn.  Qv.ekclt  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  74,  April  11)14 


317 


SOME   NOTES   ON    THE   STRUCTURE   OF   DIATOMS. 

By  N.  E.  Brown,  A.L.S. 
(Read  March  2ith,  1914.) 

Plate  23. 

These  notes  are  offered  to  the  Quekett  Microscopical  Club,  not 
-with  the  anticipation  that,  with  the  exception  of  one  point,  the 
-expert  will  find  in  them  much  that  is  not  already  known,  but 
because  my  interpretation  of  certain  familiar  features  is  different 
from  that  which  is  usually  accepted  and  may  therefore  be  of 
some  interest  in  promoting  thought  in  another  direction. 

Structure  of  Pirmuiaria  spp.  — Although  P.  major  and  allied 
species  are  familiar  to  all  microscopists  and  their  structure  is 
■doubtless  well  understood  by  experts,  yet  the  description  of  it  in 
English  text-books  is  by  no  means  satisfactory  and  also  does  not 
seem  to  be  too  well  known.  A  good  description  with  figures  by 
Floegel  will,  however,  be  found  in  the  Journal  of  the  Royal  Micro- 
scopical Society,  1884,  vol.  4,  p.  509,  t.  8  (Pinnularia). 

I  regard  P.  major  as  a  very  simple  type,  perhaps  one  of  the 
simplest  types  of  diatom-structure.  In  front  view  the  valve  pre- 
sents a  series  of  transverse  markings  on  each  side  of  the  raphe, 
which  are  so  easily  seen  that  I  believe  few  diatom- dotters  pay  much 
attention  to  them.  These  markings  consist  of  linear  cavities  or 
canals  in  the  valve,  separated  from  one  another  by  very  thin  par- 
titions, and  each  of  them  is  provided  with  a  comparatively  large 
linear-oblong  opening  on  the  inner  side,  communicating  with  the 
interior  of  the  diatom  ;  it  is  evident  that  during  life  the  protoplasm 
enters  and  fills  these  cavities,  and  therefore  they  must  play  an 
important  part  in  the  life-economy  of  the  diatom.  The  motions  of 
n  living  diatom  are  not  only  interesting  to  watch,  but  are  puzzling 
to  everv  one  who  has  observed  them.  It  is  no  uncommon  thing  to 
see  a  Pinnularia  or  other  free-swimming  diatom  apparently  take 
hold  of  a  particle  of  dirt  and  move  it  to  and  fro  along  its  sides  or 
upper  surface.  On  one  occasion  I  saw  P.  major  with  two  frag- 
ments of  dirt,  one  on  each  side  of  it  near  the  margin  ;  both  pieces 
"were  moved  forwards  and  backwards  in  the  same  direction  for 
-a  time  and  then  suddenly  they  were  moved  each  in  a  different 


318  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

direction,  and  finally  one  piece  was  passed  from  one  side  completely 
round  one  end  to  the  other  side,  where,  upon  meeting  the  other 
piece  of  dirt  which  was  moved  towards  it,  the  invisible  hands 
moving  the  dirt  lifted  it  up  and  placed  it  upon  the  other  piece  of 
dirt  and  held  it  there,  both  together  being  then  moved  up  and 
down  as  before.  Now  this  and  other  movements  I  have  witnessed 
could  only  have  been  made  at  the  will  of  the  diatom,  and  in  my 
opinion  must  have  been  controlled  by  living  matter  extruded  from 
the  interior  of  the  shell,  and  therefore  there  must  be  openings 
through  which  the  interior  is  in  communication  with  the  exterior 
other  than  at  the  raphe,  where,  as  is  well  known,  a  crest  of  proto- 
plasm extrudes,  which,  from  measurements  I  have  made,  varies 
from  l/14,000th  to  l/3,000th  inch  in  depth  and  l/6,000th  to 
1/1. 800th  inch  in  breadth.  Feeling  convinced  of  this,  I  sought 
for  several  years  for  evidence  of  pores  in  Pinnularia  without 
finding  the  slightest  trace  of  them,  and  all  authors  I  have  con- 
sulted state  that  there  are  no  openings  in  the  valve  of  Pinnularia 
other  than  at  the  raphe.  With  respect  to  diatoms  in  general,, 
in  the  8th  edition  of  The  Microscope  and  its  Revelations  (1901), 
p.  590,  it  is  stated,  "  We  have  in  fact  no  positive  demonstration 
of  the  existence  of  special  apertures  communicating  between  the 
outside  and  inside  of  the  cell." 

However,  some  four  years  ago  I  obtained  a  sample  of  the 
Chei-ryfield  diatomaceous  deposit,  and  upon  mounting  some  of  it 
in  picric  piperine,  found  that  it  contained  four  or  five  species  of 
Pinnularia,  on  one  of  which  I  at  last  saw  indications  of  the  pores. 
I  had  so  long  sought.  This  species  is  one  of  the  smallest  in  the 
material  and  the  only  one  on  which  I  have  been  able  to  see  any 
indication  of  pores.  They  are  only  to  be  seen  when  the  outer 
surface  of  the  cavities  is  accurately  in  focus  and  the  light  central, 
and  are  so  minute  and  crowded  that  they  appear  like  a  single 
dusky  beaded  line  extending  all  the  way  along  the  centre  of  the 
cavity,  and  they  do  not  appear  to  be  present  at  any  other  part.  At 
any  focal  plane  below  the  external  surface,  such  as  when  the  large 
opening  into  the  interior  of  the  diatom  is  in  view,  they  cannot  be 
seen.  When  viewed  from  the  inside  of  the  valve  they  are  scarcely 
visible  except  where  seen  through  the  large  opening  of  the  cavity 
into  the  interior.  Although  a  distinct  bead-like  appearance  is  just 
discernible,  the  pores  are  so  closely  placed  that  neither  I  nor  the- 
friends  to  whom  I  have  shown  them,  have  been  able  to  see  them 


N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS.  319 

as  distinctly  separate  dots.  It  is  only  on  this  particular  species, 
the  name  of  which  I  do  not  know,  that  I  have  been  able  to  discern 
these  pores.  Upon  the  far  larger  P.  major  and  P.  nobilis  I  can- 
not see  any  trace  of  them,  although  I  do  not  doubt  that  they 
exist  in  these  species  also,  but  are  probably  smaller  than  in  the 
species  in  which  I  discovered  them.  As  seen  by  myself  and 
friends  at  a  magnification  of  3, COO  diameters  they  are  as  repre- 
sented at  PI.  23,  fig.  13. 

Upon  the  sides  or  girdle  of  all  species  of  Pinnularia  are  to  be 
seen  two  slender  lines,  which  under  sufficient  magnification  are 
seen  to  be  composed  of  a  multitude  of  short  transverse  lines  ;  in 
P.  major  these  average  about  60,000  to  the  inch.  These  lines  I 
have  failed  to  resolve  into  distinct  dots,  although  Mr.  E.  M. 
Nelson  (Journ.  Q.M.C.,  Ser.  2,  Vol.  VI.  p.  144)  states  that  he 
has  done  so,  and  I  do  not  doubt  his  statement.  But  at  the  same 
time  I  very  much  doubt  if  the  clots  of  which  these  transverse 
lines  are  composed  are  real  pores.  The  lines  are  so  easily  seen 
that  they  evidently  are  much  too  coarse  for  pore  structure,  and 
my  interpretation  of  the  structure  of  these  two  lines  on  the 
girdle  of  Pinnularia  is,  that  each  line  consists  of  a  multitude 
of  very  minute  cavities  placed  side  by  side,  similar  to  those  seen 
in  the  front  view  of  the  valve,  and  that  when  they  are  truly 
resolved  each  cavity  will  be  found  to  have  a  minute  pore  at  the 
centre  or  a  row  of  pores  along  the  central  line  of  each  cavity  or 
clear  space  between  every  pair  of  short  transverse  lines. 

It  may  be  well  to  state  that  there  are  sometimes  appearances 
to  be  seen  on  the  walls  of  the  cavities  of  P.  major  and  P.  ?iobilis 
which  may  easily  be  mistaken  for  rows  of  pores.  As  I  have 
seen  them,  they  appear  like  two  rows  along  each  cavity,  but 
upon  moving  the  mirror  slightly  these  rows  move  also,  and 
clearly  demonstrate  that  they  are  only  diffraction  images. 
The  true  pores  of  these  species,  when  discovered,  will,  I  believe, 
be  in  one  central  row. 

Pleurosigma  balticuni. — In  a  paper  recently  published  in  the 
Journ.  Q.M.  6'., Ser.  2, Vol.  XII.  p.  155,  Mr.  T.  O'Donohoe  has  given 
an  account,  accompanied  by  some  excellent  photographs,  of  certain 
details  of  structure  of  this  diatom  as  seen  in  a  strewn  slide 
mounted  in  realgar  belonging  to  Mr.  B.  J.  Capell.  By  the 
courtesy  and  kindness  of  Mr.  Capell  I  have  also  had  the  privilege 
of  examining  this  slide,  and  am  fortunate  enough  to  be  able  to 


320  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

add    something  concerning  the  structure  to  be  seen  on  it  that 
appears  to  have  escaped  the  eyes  of  Mr.  O'Donohoe. 

In  the  process  of  melting  the  realgar,  either  the  great  heat 
required,  or  some  chemical  action  set  up  by  it,  has  acted  upon 
some  specimens  of  P.  balticum  and  completely  dissolved  part 
of  the  shell,  leaving  only  film-like  strips  flattened  upon  the 
cover-glass,  whilst  others  have  been  quite  unaffected.  One 
specimen  shows  in  a  very  clear  manner  the  dissolving  action  in 
progress,  but  arrested  at  the  moment  when  a  subcentral  part 
of  the  diatom  had  become  fused  into  a  structureless  strand  of 
silica,  connecting  the  two  ends,  which  remain  intact.  These 
films  above  mentioned,  which  Mr.  O'Donohoe  has  photographed, 
will  prove,  I  think,  to  have  an  important  bearing  upon  our 
more  complete  understanding  of  diatom  structure. 

If  the  outer  surface  of  a  perfect  valve  of  P.  balticum  be 
examined  under  a  binocular,  it  will  be  seen  that  the  sides  curve 
away  from  the  raphe  very  much  as  the  sides  curve  away  from 
the  keel  of  a  boat  when  turned  bottom  upwards,  so  that  the 
surface  is  nearly  always  oblique  to  the  surface  of  the  cover- 
glass.  From  this  cause  I  have  found  the  structure  of  a  perfect 
specimen  extremely  difficult  to  understand,  as  a  very  slight 
modification  of  the  illumination  or  alteration  of  focus  under  high 
powers,  or  the  two  combined,  produce  a  number  of  different 
appearances — six  or  seven  have  been  noticed — all  apparently 
demonstrating  true  structure,  so  that  it  is  practically  impossible 
to  form  an  opinion  as  to  which  view,  or  views,  represent  the  real 
structure  of  the  valve.  Owing  to  this,  I  suppose,  has  arisen  the 
diverse  views  held  of  the  structure  by  different  authors.  0.  Miiller, 
for  instance,  in"  the  Deutschen  Botanischen  Gesellschaft  for  1898, 
Vol.  XVI.  p.  387,  t.  26,  fig.  8,  regards  the  pores  (by  which 
I  understand  he  means  the  black  dots)  in  the  cell- wall  as 
perforations  passing  completely  through  the  wall,  which  are 
not  perfectly  tubular,  but  enlarged  at  their  centre  and  contracted 
to  a  minute  opening  on  the  internal  and  external  surface  of  the 
valve  thus  : 


porej 

Mr.    T.    F.  Smith,  however,    in   the  Journ.    Q.  M.  C,  Ser.  2, 


N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS.  321 

Vol.  III.  p.  306,  regards  the  valve  as  "composed  of  two  layers 
of  grating";  whilst  Mr.  E.  M.  Nelson  in  the  Journ.  Q.M.C., 
Ser.  2,  Vol.  XII.  p.  99,  fig.  4,  states  that  "  in  P.  balticum 
and  allied  forms  the  upper  membrane  has  slit-like  apertures  in 
longitudinal  rows,  while  the  lower  membrane  has  circular 
apertures  (fig.  4),  where  the  circular  apertures  in  the  lower 
membrane  are  seen  through  the  intercostal  silex  of  the  upper 
membrane  and  in  a  line  between  the  slits."  Finally  we  have 
Mr.  O'Donohoe's  interpretation  referred  to  above. 

Until  August  1913  I  held  the  view  (which  I  think  is  the 
prevailing  one)  that  the  black  dots  visible  on  the  valve  of  a 
diatom  were  pores  or  perforations  passing  completely  through 
its  substance,  and  that  the  white-dot  view  was  an  out-of-focus 
one.  Now,  however,  the  examination  of  Mr.  Capell's  slide  has 
demonstrated  to  me  and  to  others  who  have  examined  it  with 
me,  conclusively  and  beyond  any  room  for  doubt,  that  many 
(possibly  all)  of  the  black  dots  that  are  ordinarily  seen  on  a- 
diatom  are  not  pores  at  all,  or  at  the  most  are  only  pits  con- 
taining the  pore-bearing  membrane,  and  that  the  white-dot  view 
is  often  much  more  correct  for  seeing  what  I  believe  to  be  the 
true  pore-structure  than  has  been  supposed. 

I  have  long  been  puzzled  at  the  behaviour  of  black  dots  under 
high  magnification,  and  have  therefore  suspected  that  they 
were  not  quite  what  they  seemed  to  be  for  some  time  past,  but 
I  think  the  evidence  of  Mr.  Capell's  slide  fully  explains  their 
nature. 

In  any  perfect  valve  of  P.  balticum  it  is  easy  to  obtain  a  view 
of  a  grating-like  structure  with  square  meshes,  formed  of  bars- 
or  rods  of  silex  crossing  one  another  at  right  angles.  In  the 
partly  dissolved  films  on  Mr.  Capell's  slide  this  grating  is  not 
evident,  but  instead  the  films  are  seen  to  consist  of  parallel 
dark  rods  having  a  beaded  appearance,  held  in  place  by  a 
membrane  of  silex  (see  Mr.  O'Donohoe's  figures,  op.  cit.,  t.  14r 
figs.  3  and  4).  At  the  ends  or  other  parts  the  rods  are  seen 
to  project  in  a  ragged  manner.  These  rods  are  those  which  lie 
parallel  to  the  raphe  in  the  perfect  grating,  while  those  which 
in  the  perfect  diatom  form  the  transverse  bars  of  the  grating 
structure  have  been  dissolved,  leaving  no  trace,  or  only  a  very 
faint  one,  visible.  When  examined  with  an  oil-immersion  objective 
at  a  magnification   of   2,000  to  3,000   diameters  these  bars  are 


322  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

seen  to  be  thickened  in  a  beaded  manner  at  short  equal  intervals. 
Tn  some  cases  a  few  of  these  rods  are  curved  away  from  the 
surface  of  the  valve,  and  one  of  them  in  such  manner  that  part 
is  seen  in  surface  view  and  part  seen  in  side  view,  and  traceable 
from  one  view  to  the  other  (see  Mr.  O'Donohoe's  photograph, 
op.  cit.,  t.  14,  fig.  2.  where  it  or  a  similar  rod  is  shown  out  of 
focus).  Now  it  is  obvious  that  the  bead-like  swellings  occur  at 
the  points  where,  in  the  perfect  grating,  the  transverse  bars 
■crossed  and  were  fused  with  those  parallel  to  the  raphe,  and 
that  these  transverse  bars  were  either  more  easily  dissolved  or 
lie  at  a  slightly  lower  level  than  the  longitudinal  bars,  and  so 
are  more  quickly  attacked  by  the  dissolving  action.  In  all  cases 
the  films  are  very  closely  appliel  to  the  cover-glass,  indicating 
that  its  cooler  surface  has  in  some  way  retarded  the  dissolving 
process,  so  that  the  parts  of  the  diatom  farthest  from  the  cover - 
glass  were  always  dissolved  first.  That  the  longitudinal  bars  over- 
lie the  transverse  bars  seems  to  be  probably  the  correct  view,  as 
under  certain  conditions  of  illumination  the  longitudinal  bars  seem 
to  pass  over  the  transverse  ones,  and  is  supported  by  the  testimony 
of  the  curved  bar  mentioned  above  as  seen  in  side  view.  At 
a  magnification  of  3,000  diameters  it  is  clearly  seen  that  the 
edge  of  the  bar  facing  the  outside  of  the  diatom  is  perfectly 
even,  while  the  edge  facing  the  interior  projects  into  little  hemi- 
spheres at  the  points  where  (in  surface  view)  it  is  bead-like  (fig.  2). 
Also  at  the  marginal  part  of  the  valve,  where  the  longitudinal 
bars  are  normally  undeveloped  and  only  the  transverse  bars 
are  evident,  these  latter  become  pressed  nearer  to  the  cover- 
glass,  and  are  not  dissolved. 

The  bars  can  be  distinctly  seen  to  be  solid  pieces  of  silex,  which 
go  to  form  the  strengthening  grating  and  support  the  membrane 
which  covers  the  exterior  of  the  diatom.  At  a  certain  focus  the 
beads  or  nodes  at  the  crossing  of  the  bars,  owin2f  to  refraction 
or  diffraction,  assume  the  appearance  of  black  dots  so  familiar  to 
all  microscopists,  demonstrating  conclusively  that  these  black 
dots  are  not  pores,  but  shadows  produced  by  some  refractive 
or  diffractive  property  of  the  nodes  of  the  grating-bars. 

From  the  movements  T  have  seen  diatoms  perform  it  is  evident 
they  must  have  some  means  of  communication  through  the  valves 
with  their  surroundings,  and  finding  that  the  black  dots  on  this 
diatom  are  certainly  not  pores,  I  sought  for  them  in  the  membrane 


X.    E.    BROWN    OX    THE    STRUCTURE    OF    DIATOMS.  323 

covering  the  meshes  of  the  grating.  This  membrane  is  extremely- 
thin,  probably  not  thicker  than  the  film  of  a  soap-bubble,  and 
is  raised  into  a  slight  dome  or  convexity  over  each  mesh  of  the 
grating.  When  the  apex  of  these  convexities  is  accurately  in 
focus,  and  the  headings  of  the  bars  seen  as  black  dots  forming 
squares,  the  light  being  central  and  with  a  magnification  of 
2,000  to  3,000  diameters,  a  very  minute  dot  is  seen  at  the 
centre  of  each  square  (PI.  2,  fig.  1).  This  central  spot  I  conceive 
to  be  a  true  pore  through  the  membrane ;  it  is  very  minute,  at 
the  most  not  more  than  one-third  of  the  diameter  of  the  black 
dots  themselves,  and  is  probably  not  more  than  1/200, 000th  of  an 
inch  in  diameter.  It  is  not  quite  easy  to  see,  but  can  be  made 
clearer  by  the  use  of  a  small  central  stop  in  the  substage  con- 
denser. I  doubt  if  it  can  be  seen  at  all  at  a  less  magnification 
than  1,000  diameters;  and  with  a  dry  Zeiss  y-th,  at  a  magnification 
of  3,000  diameters,  I  do  not  feel  quite  sure  that  I  see  the  pores. 
There  seems  a  suggestion  of  their  presence,  but  I  do  not  think 
any  dry  lens  will  show  them  very  clearly.  Under  dark-ground 
illumination,  with  a  Leitz  dark-ground  illuminator,  the  bars 
are  white  and  the  headings  on  them  appear  much  larger  than 
when  seen  by  direct  light,  whilst  the  membrane  is  not  seen  at 
all,  the  spaces  between  the  bars  being  black.  But  if  the  funnel- 
stop  which  cuts  down  the  aperture  of  the  lens  is  removed,  the 
illumination  remaining  as  before,  then  the  bars  appear  to  be 
very  slender  and  black  and  the  membrane  whitish,  with  the 
minute  pores  clear  and  distinct. 

Upon  entire  specimens  of  the  diatom  the  pores  are  difficult  to 
see,  apparently  owing  to  the  convex  curvature  of  the  shell,  but 
with  a  little  trouble  I  have  been  able  to  see  them  in  places  upon 
every  specimen  examined.  Under  certain  conditions  of  illumina- 
tion a  small  dark  spot,  which  might  easily  be  mistaken  for  the 
pore,  is  seen  at  the  centre  of  each  of  the  beads  of  the  membrane  ; 
this  spot,  however,  is  very  much  larger  than  the  true  pore, 
and  appears  to  be  some  diffraction  image,  possibly  that  of  the  stop 
in  the  condenser,  as  can  easily  be  demonstrated  by  moving  the 
mirror  slightly,  when  the  spot  is  seen  to  shift  its  position. 

Although  all  to  whom  I  have  shown  these  pores  agree  with  me 
that  they  are  very  minute,  yet  they  appear  to  have  a  different 
size  to  different  observers.  To  my  eye  they  appear  to  have  about 
the  proportion  to  the  black  dots  I  have  represented  in  my  drawing, 

Journ.  Q.  M.  C,  Series  II.— No.  74.  23 


324  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. N 

to  others  the}7  evidently  seem  larger,  as  one  friend  said  he  thought 
that  about  five  of  them  just  touching  one  another  would  extend 
right  across  one  of  the  meshes  of  P.  balticum,  but  even  at  that 
rate  they  would  not  be  more  than  1/1 80,000th  of  an  inch  in  dia- 
meter, whilst  I  think  they  cannot  be  more  than  l/200,000th 
of  an  inch  in  size. 

With  regard  to  Mr.  Smith's  statement  that  there  is  a  second 
grating,  I  have  not  the  slightest  doubt  that  the  transverse  bars 
form  such  a  grating,  but  I  have  not  seen  it  separately  from  the 
outer  grating.  In  Knowledge  for  1911,  p.  334,  Mr.  Smith 
reproduces  a  photograph  of  P.  balticum  in  which  the  longi- 
tudinal strengthening  bars  are  shown  and  are  there  called 
"  fibrils,"  a  term  which  Mr.  O'Donohoe  has  also  adopted,  but 
which  to  me  seems  wholly  inapplicable,  as  they  appear  to  me  to  be 
supporting  structures  for  the  delicate  membrane  and  in  no  sense 
ultimate  structures.  It  may  not  be  out  of  place  here  to  point 
out  that  the  membrane  I  speak  of  and  illustrate  is  a  totally 
different  thing  from  that  which  Mr.  Smith  in  the  Joum.  Q.  M.  0.f 
Ser.  2,  vol.  3,  p.  301,  t.  3,  fig.  5,  and  in  Knowledge  (1911),  pp.  289- 
93,  and  221-35,  and  (1912)  p.  371  describes  and  figures  as  a 
"delicate  membrane'3  and  "torn  structure."  For  it  is  a 
matter  of  great  surprise  to  me  that  Mr.  Smith  did  not  recognise 
that  this  supposed  "delicate  membrane  "  and  "torn  structure" 
has  no  morphological  connection  with  the  diatom.  I  had  sup- 
posed, previous  to  reading  his  paper,  that  every  one  regarded 
this  appearance  merely  as  an  incrustation  cementing  the  diatom 
to  the  cover-glass ;  it  is  of  very  common  occurrence  upon 
Pleurosigma  and  some  other  diatoms.  I  have  always  regarded 
it  as  due  to  the  exudation  of  a  residual  salt,  which,  after 
boiling  in  acid,  has  not  been  thoroughly  washed  out  of  the  diatom 
(and  it  is  indeed  very  difficult  to  wash  out  completely),  so  that 
when  mounting  them  on  a  cover-glass  the  water  outside  the 
diatom  evaporates  first  and  the  salt  then  gradually  percolates  out 
through  the  pores  of  the  diatom,  and,  in  drying,  fixes  it  to  the 
cover-glass,  and  being  of  low  refractive  index  produces  the 
appearance  we  so  often  see. 

It  will  be  noted  that  there  is  a  discrepancy  between  my 
drawings  and  Mr.  O'Donohoe's  photographs  in  the  size  of  the 
black  dots,  for  although  mine  are  represented  at  a  greater 
magnification,  they  are  smaJler  than  in  the  photograph.     This  is. 


X.    E.    BROWN    ON    THE    STRUCTURE   OF    DIATOMS.  325 

probably  because  the  photographs  were  taken  at  a  focus  where 
the  membrane  is  not  visible  and  where  diffraction  effects  are  at  a 
maximum,  whilst  at  the  focus  of  the  surface  of  the  membrane 
they  are  reduced  to  a  minimum. 

Since  writing  the  above  I  have  had  the  advantage  of  being  able 
to  examine  a  realgar  mount  of  P.  balticum  belonging  to  Mr.  E. 
M.  Nelson.  The  realgar  of  this  slide  is  not  nearly  so  clear  and 
brilliant  as  that  of  Mr.  CapelTs  slide,  and  on  some  parts  of  it  I 
cannot  see  the  pores  in  the  films  at  all,  but  there  are  some  films 
where  they  can  be  most  distinctly  seen.  I  mention  this,  because 
others  possessing  realgar  mounts  of  this  diatom  might  fail  to  find 
the  pores  on  some  of  the  films  and  believe  them  not  to  be  present ; 
they  may  be  extremely  difficult  to  make  out,  or  quite  invisible  on 
parts  of  the  valve  where  both  longitudinal  and  transverse  grating 
or  strengthening  bars  are  present. 

Pleurosigma  angulatum. — Upon  Mr.  Oapell's  realgar  slide 
are  also  numerous  specimens  of  this  diatom  ;  some  are  bent  or 
contorted,  but  otherwise,  with  the  exception  of  two  or  three 
specimens,  seem  unaffected  by  the  heat  or  dissolving  action. 
One  of  these  exceptions,  however,  is  an  exceedingly  interesting 
specimen,  and  clearly  confirms  Mr.  E.  M.  Nelson's  statement  in 
the  Journ.  Q.  M.  C,  Ser.  2,  Vol.  XII.  pp.  98-100,  that  the  valve 
of  this  diatom  is  composed  of  two  gratings.  It  is  a  single  valve 
and  therefore  its  structure  is  not  obscured  by  images  from  the 
opposing  valve,  is  fractured  in  places,  and  has  its  outer  surface 
next  the  cover-glass,  as  can  be  verified  by  examination  under  a 
binocular.  Over  a  small  area  some  solvent  has  caused  a  portion 
of  the  outer  grating  to  peel  off,  and  at  one  place  a  small  patch  of 
it  is  seen  adhering  to  the  cover-glass ;  this  patch  is  represented  at 
fig.  5,  as  seen  when  magnified  3,000  diameters.  At  this  magnifi- 
cation the  bars  of  silex  forming  the  boundaries  of  the  meshes  are 
seen  to  cross  one  another  diagonally,  forming  diamond-shaped 
meshes,  and  are  thickened  at  the  nodes  or  points  of  intersection 
just  as  in  P.  balticum,  and,  as  in  that  diatom,  it  is  these  nodes 
which  produce  the  black-dot  appearance.  At  the  centre  of 
the  membrane  covering  each  mesh  a  very  minute  pore  can  be 
seen  when  the  surface  of  the  membrane  is  accurately  in  focus. 
These  pores  do  not  seem  to  be  visible  under  direct  central  light 
without  the  interposition  of  a  stop  in  the  condenser,  and  I  find 
that  they  are  best  seen  when  illuminated  by  means  of  a  Leitz 


326  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

dark-ground  illuminator,  but  without  using  a  funnel-stop  in  the 
lens.  Under  this  method  of  illumination  they  are  remarkably 
clear  and  distinct,  and  the  membrane  itself  appears  to  be  slightly 
concave  as  viewed  from  the  outside  of  the  valve.  At  one  focus 
and  under  slightly  oblique  illumination,  one  set  of  bars  appears  to 
cross  over  the  other  set,  as  I  have  represented  diagrammatically  at 
fig.  6  ;  at  this  focus  the  pores  are  invisible.  Upon  the  specimen 
from  which  the  fragment  is  separated  both  the  outer  and  inner 
gratings  are  seen  to  be  composed  of  hexagonal  meshes,  as  at 
figs.  7  and  8,  and  I  find  it  very  difficult  to  get  a  view  of  the 
diamond-shaped  meshes  on  the  entire  part  of  this  particular 
specimen,  although  upon  other  specimens  I  have  been  able  to  see 
them  and  the  pores  very  clearly  and  easily,  as  well  as  the  under- 
lying hexagonal  meshes.  It  would  seem  as  if  the  outer  grating 
may  really  be  a  double  structure,  with  a  film  of  diamond-shaped 
meshes  overlying  others  that  are  hexagonal. 

Under  certain  conditions  of  illumination  a  third  set  of  bars  can 
be  seen  on  entire  specimens,  crossing  the  diagonals  at  right  angles 
to  the  raphe,  but  I  have  failed  to  see  any  trace  of  them  on  the 
separated  fragment  represented  at  fig.  5,  so  that  I  think  it  very 
probable  that  they  have  been  dissolved  away  from  that  piece, 
just  as  also  appears  to  have  been  the  case  in  the  films  of 
P.  balticum.  For  I  think  there  can  be  no  doubt  that  some  such 
bars  exist,  because  at  one  focus,  under  varying  conditions  of 
illumination,  the  gratings  appear  to  be  composed  of  nearly  square 
meshes  as  represented  at  fig.  9.  At  a  very  slight  alteration  of 
focus  this  appearance  alters  to  the  hexagonal  one  as  represented  at 
figs.  7  and  8,  which  I  take  to  be  that  of  the  exact  focal  plane  of 
the  membrane  covering  the  meshes  of  that  particular  grating. 
When  the  inner  grating  is  examined  where  the  outer  grating  is 
stripped  off,  looking  upon  it  from  the  outside  of  the  valve,  it  first 
presents  the  appearance  of  a  solid  plate  of  white  silex  with  dark 
hexagonal  perforations  in  it.  At  a  slightly  lower  focus  this  gives 
place  to  hexagonal  meshes  with  dark  boundaries  and  the  mesh 
covered  with  a  clear  membrane  having  a  pore  at  its  centre  ;  this 
latter  I  look  upon  as  being  the  true  image  of  the  inner  grating 
and  the  above-mentioned  appearance  of  a  white  plate  with  dark 
perforations  as  an  out-of-focus  image  produced  by  some  refractive 
or  diffractive  property  of  the  membrane,  which  in  some  way 
produces  over  each  mesh  a  hexagonal  shadow.     Below  the  focus 


N.    E.     BROWN    ON    THE    STRUCTURE    OF    DIATOMS.  327 

of  the  hexagonal  meshes  I  can  sometimes  make  out  a  diamond- 
shaped  arrangement  of  dark  dots  as  seen  in  fig.  5.* 

In  this  species,  as  in  P.  balticum,  wherever  a  junction  of  two 
or  more  bars  of  a  grating  occurs,  there  a  black  dot  is  seen,  due  to 
diffraction  or  refraction  of  the  node  so  formed.  And  in  my 
opinion  wherever  grating  structure  occurs,  the  nodes  may  be 
expected  to  appear  as  black  dots. 

At  one  place  a  fragment  of  the  valve  is  broken  off  and  turned 
edgeways  to  the  cover-glass.  This  edge-view  shows  the  two 
gratings  distinctly,  but  at  the  same  time,  owing  to  the  shadow  of 
the  mass,  I  am  quite  unable  to  see  how  they  are  connected  to  each 
other.  But  from  an  examination  of  this  piece,  as  well  as  of  the 
valve  where  the  outer  grating  is  stripped  off,  it  is  evident  that 
the  faint  brown  colour  peculiar  to  this  diatom  resides  in  the  outer 
grating,  the  inner  one  being  colourless. 

I  cannot,  however,  confirm  Mr.  Nelson's  statement  (Journ. 
Q.  M.  C,  Ser.  2,  Vol.  XII.  p.  99)  that  the  meshes  of  the  outer 
and  inner  grating  alternate  with  one  another,  for  in  this  particu- 
lar specimen  I  think  there  can  be  no  question  that  the  meshes  of 
the  outer  grating  are  exactly  superposed  over  those  of  the  inner 
grating  when  seen  with  exactly  central  light.  I  have  tested  them 
several  times  by  the  unaided  eye  and  by  means  of  a  micrometer 
in  the  eye-piece,  and  always  found  them  to  correspond,  except 
when  the  light  was  not  absolutely  central.  Also  the  edge- view 
confirms  their  superposition  so  far  as  I  have  been  able  to  make  it 
out,  but  it  is  very  difficult  to  get  a  really  good  focal  image  of  this 
part. 

P.  angulation  has  one  very  obvious  peculiarity  which  I  do  not 
remember  to  have  seen  mentioned,  namely,  that  at  the  ends  of  the 
valve  the  grating  suddenly  changes  from  the  hexagonal  to  the 
square  type  of  mesh.     This  should  form  a  good  specific  character. 

Surirella  gemma. — Mixed  with  Phurosigma  balticum  on  Mr. 
Capell's  slide  are  numerous  specimens  of  Surirella  gemma,  which, 

*  Mr.  T.  F.  Smith  is  of  opinion  that  the  outer  grating  is  different  in 
structure  from  the  inner  grating,  and  views  of  both  gratings  are  given  in 
The,  Microscope  and  its  Revelations,  8th  ed.  p.  593,  pi.  1,  figs.  1  and  2.  I 
am  not  able  to  confirm  this  view,  for  every  structural  image  seen  on  the 
outer  grating  I  have  also"been  able  to  see  on  the  inner  grating — it  is  merely 
a  question  of  focus  and  illumination.  The  "delicate  membrane"  on  the 
outside  of  the  shell  described  by  Mr.  Smith  I  have  already  noted  under 
P.  balticum,  so  need  not  make  any  further  remark  upon  it. 


328  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

in  consequence  of  having  seen  the  minute  pores  in  P.  balticum,  I 
eagerly  examined,  as  I  was  reminded  that  some  four  years  ago 
whilst  examining  S.  gemma  mounted  in  styrax  with  a  Leitz 
-jL.th  achromatic  oil-immersion  objective  of  1*3  N.A.  I  had  seen 
similar  pores  or  dots  on  the  white  beads  of  that  diatom.  At  the 
time,  being  very  busy  with  other  work  and  thoroughly  accepting 
the  opinion  that  the  black  dots  usually  seen  were  pores,  I  paid  no 
attention  to  what  I  then  saw.  Now,  however,  I  examined  them 
with  fresh  interest  and  found  that  in  this  realgar  mount  the  pores 
are  distinctly  visible.  To  see  them,  the  valve  must  be  resolved 
into  a  grating  formed  of  slender,  slightly  zigzag  black  bars,  with 
the  interspaces  divided  by  very  slender  transverse  partitions  into 
small  meshes  (the  so-called  white-dot  focus).  At  a  magnification 
of  from  1,800  to  3,000  diameters  on  some  specimens,  but  not  all,  a 
minute  dark  speck  or  pore  at  the  centre  of  every  one  of  the 
meshes  is  very  clearly  visible  (figs.  3  and  4)  ;  at  the  same  time 
it  is  so  minute  that  it  requires  good  eyesight  to  perceive  it, 
but,  as  in  other  cases,  becomes  accentuated  if  a  small  stop  be 
placed  in  the  carrier  of  the  condenser.  There  is  therefore  no  very 
great  difference  in  the  ultimate  structure  of  this  Surirella  and  of 
Pleurosigma  balticum,  except  that  in  the  latter  it  is  the  bars 
parallel  to  the  longer  axis  of  the  diatom  which  are  most  evident, 
whilst  in  Surirella  gemma  the  bars  transverse  to  that  axis  are  the 
most  apparent.  It  must  be  understood  that  I  refer  here  only  to 
the  fine  secondary  bars  or  those  of  the  cell-wall,  not  to  the  stout 
primary  bars  which  form  the  framework  of  the  diatom  and  sup- 
port the  cell- wall.  The  nodes,  formed  by  the  junction  of  the 
slender  partitions  with  the  bars,  at  another  focus  produce  the  ap- 
pearance of  black  dots  by  refraction  or  diffraction  as  they  do  in 
Pleurosigma  balticum.  One  specimen  of  S.  gemma  on  the  slide  is 
crumpled  up  and  the  bars  bent  and  turned  aside  so  as  to  show 
their  nature  very  clearly  when  sufficiently  magnified,  and  demon- 
strate that  they  are  exactly  of  the  same  character  as  those  of 
Pleurosigma  balticum — that  is,  they  are  the  strengthening  bars  of 
the  membrane  of  the  diatom.  I  have  been  unable  to  determine 
whether  there  is  also  a  membrane  over  the  inner  surface  of  these 
bars,  but  think  it  very  probable,  in  which  case  the  white  bead- 
like appearance  will  be  chambers  with  minute  orifices  in  their 
iuner  and  outer  wall. 

This  diatom  seems  to  provide  the  microscopist  with  a  series  of 


N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS.  329 

tests  ;  with  lenses  having  a  smaller  aperture  than  about  0  68  N.  A. 
only  the  primary  bars  of  the  framework  are  visible ;  with  lenses 
of  a  larger  aperture,  the  secondary  bars  (i.e.  those  of  the  cell- wall) 
become  manifest  as  very  fine  lines  between  the  primary  bars; 
finally  with  lenses  of  large  aperture  and  at  a  magnification  of  not 
less  than  1,800  diameters  these  fine  lines  or  bars  are  seen  to  b9 
connected  by  finer  transverse  bars  so  as  to  form  a  ladder-like 
structure,  with  a  minute  pore  at  the  centre  of  each  bead-like 
space  formed  by  the  cross  bars,  or  at  another  focus  the  bars  can 
be  resolved  into  the  appearance  of  rows  of  dots. 

Navicula  serians.— The  structure  of  the  valve  of  this  species 
seems  rather  difficult  to  understand.  When  I  first  examined  it 
in  search  of  pores,  I  found  it  had  a  rather  coarse  grating,  with 
oblong  meshes  arranged  in  six  to  seven  rows  on  each  side  of  the 
raphe,  the  longer  diameter  of  the  meshes  being  transverse  to  the 
latter.  These  meshes  are  closed  by  a  very  thin  membrane  of 
silex,  at  the  centre  of  which  can  be  seen,  at  a  magnification  of 
3,000  diameters,  a  minute  dark  dot,  as  represented  at  the  upper 
part  of  fig.  10.  This  clot  I  take  to  be  a  pore.  With  central 
light  only  a  very  faint  indication  of  it  is  seen ;  but  when  a  small 
central  stop  is  placed  in  the  condenser  it  becomes  clearly  visible. 
This  structure  is  all  that  I  at  first  noted.  But  having  re- 
examined this  diatom  with  great  care  under  all  conditions  of 
illumination  at  my  command,  I  have  detected  structure  which  had 
previously  entirely  escaped  my  notica.  For  I  find  that  if  the 
outer  surface  of  the  valve  is  illuminated  by  a  Leitz  dark-ground 
illuminator  and  examined  at  a  magnification  of  not  less  than 
2,000  diameters,  without  reducing  the  N.A.  by  using  a  funnel- 
stop,  a  second  grating  exterior  to  and  superposed  ^upon  that 
above  described  can  be  distinctly  seen.  This  outer  grating  is 
evidently  extremely  transparent  and  practically  invisible  by 
central  light,  so  that  it  very  easily  escapes  notice.  I  have  found 
that  the  easiest  way  to  make  it  evident  is,  first  to  get  [the  mem- 
brane of  the  coarse  meshes  in  focus,  as  represented  at  the  upper 
part  of  fig.  10,  then  gradually  but  very  slightly  raise  the  lens 
above  that  focal  plane,  until  two  dark  dots  appear  over  each 
mesh.  If  these  dots  are  very  accurately  focused  and  the  dark- 
ground  illuminator  manipulated  so  as  to  illuminate  the  diatom 
with  light  reflected  upon  it  from  the  under  surface  of  the  cover- 
glass,  the  surface  of  the  valve  will  be  found  to  have  the  'appear- 


330  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

ance  I  have  tried  to  represent  at  the  lower  part  of  fig.  10.  I 
believe  that  each  of  these  dots,  or  minute  meshes  as  they  really 
are,  is  closed  by  an  extremely  thin  membrane  of  silex,  as  on  one 
occasion,  when  using  a  dim  light  reflected  from  the  cover-glass 
upon  the  diatom,  the  presence  of  such  a  membrane  seemed  to  be 
very  distinctly  evident  by  the  light  reflected  from  its  surface  over 
each  dark  spot  and  nowhere  else.  But  I  entirely  failed  to  see 
the  slightest  trace  of  a  pore  in  it,  although  I  think  it  probable 
that  one  exists  in  each  mesh. 

Nitzschia  scalaris. — When  the  fine  striae  on  this  diatom  are 
magnified   up   to   3,000   diameters,   they   are  seen  to  consist    of 
small  beads  or  pearl-like  dots  of  silex,  which  are  either  black  or 
white  according  to  illumination.     Upon  the  very  thin  membrane 
between  each  pair  of  these  rows  of  beads,  a  row  of  very  minute 
pores   is  just   discernible,   as  represented    at    fig.    11,    which    is 
drawn   with   a   camera-lucida,   using   central   light   and  a  green 
screen.      Under  the  best  of  circumstances  they  are  exceedingly 
faint,  and  I  am  not  at  all  sure  that  they  are  accurately  spaced 
in  my  drawing,  as  I  found  it  exceedingly  difficult  to  plot  them  on 
paper   by  means  of   a  camera-lucida  ;   but  the  drawing  is  suffi- 
ciently accurate  to  show  their  position.     It  requires  good  eyesight 
to  see  them  at  all,  and  I  do  not  think  they  would  be  visible  at  a 
less   magnification   than    2,500  diameters.      The    light    must    be 
most    carefully   manipulated,   and   for   my  vision   I   have  found 
them  to  be  most  evident  in  a  rather  dim  light,  a  glare  effaces 
them ;  also  at  a  very  slight  touch  of  the  fine  adjustment  they 
instantly  vanish.     As  a  test  for  high  powers,  manipulative  skill 
and  keenness  of  vision,  I  think  few  things  can  be  found  more 
suitable   than  the   resolution  of  the  pores  of  this  diatom  when 
mounted  in  styrax. 

Amphipleura  Lindheimeri. — When  the  surface  of  this 
diatom  is  accurately  in  focus  (not  the  black-dot  view),  a  fine 
grating  with  square  meshes  is  seen,  which  somewhat  resembles 
that  of  Surirella  gemma ;  the  bars  transverse  to  the  raphe  being 
straight,  whilst  those  parallel  to  the  raphe  form  sinuous  lines, 
because  the  ends  of  the  short  partitions  which  divide  the  space 
between  each  pair  of  transverse  bars  into  square  meshes  do  not 
exactly  coincide  with  the  ends  of  the  partitions  between  the 
adjoining  pairs  of  transverse  bars.  At  a  magnification  of  3,000 
diameters,    when    the    membrane    covering    the    meshes    of    the 


N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS.  331 

grating  shows  a  somewhat  bead-like  appearance,  a  very  minute 
dusky  dot,  which  I  take  to  be  a  pore,  is  just  discernible  in  the 
centre  of  every  one  of  them,  as  represented  in  fig.  12.  These 
pores,  I  think,  are  smaller  even  than  those  of  Sarirella  gemma, 
and  are  very  difficult  to  see,  unless  perhaps  to  younger  eyes,  as 
I  judge  them  to  be  about  the  limit  of  my  vision.  At  a  slightly 
lower  focus  the  nodes  formed  by  the  junctions  of  the  transverse 
and  longitudinal  bars  assume  the  well-known  black-dot  appear- 
ance, and  all  trace  of  the  other  structure  disappears.  Doubtless 
the  structure  of  A.  pellucida  is  similar. 

Coscinodiscus  heliozoides. — I  have  nothing  to  remark 
upon  the  structure  of  the  diatom  to  which  Mr.  Siddall  recently 
gave  the  above  name;  but  I  should  like  to  call  the  attention  of 
experts  to  its  remarkable  similarity  to  Stepkanodiscus  Hantz- 
schianus.  I  have  not  been  able  to  compare  the  two,  but  feel 
sure  that  C.  heliozoides  belongs  to  the  genus  Stephanodisats, 
and  have  a  suspicion  that  it  and  S.  Ilantzschianus  are  one 
and  the  same  diatom.  A  good  figure  of  the  latter  will  be  found 
in  the  Deutschen  Boianischen  GesellscJiaft,  1S97,  vol.  15,  t.  25, 
h>   1 

Stauroneis  phoenicenteron. — When  examined  at  a  magni- 
fication of  a  few  hundred  diameters,  the  valve  of  this  diatom  is 
seen  to  be  prettily  marked  with  black  dots  ;  but  when  magnified 
2,000  to  3,000  diameters  and  very  accurately  focused,  the  black 
dots  are  seen  to  be  optical  effects  produced  by  the  membrane 
closing  the  meshes  of  the  grating.  This  membrane  is  slightly 
sunk  below  the  general  level  of  the  surface  of  the  grating  so  as 
to  form  shallow  pits.  When  viewed  with  the  light  quite  central, 
without  a  stop,  the  bars  of  the  grating  appear  very  much  stouter 
and  the  meshes  smaller  and  not  so  well  defined  as  they  do  by 
other  methods  of  illumination,  and  I  have  quite  failed  to  detect 
any  trace  of  pores  in  the  membrane  by  this  method.  But  when 
oblique  illumination  is  used,  either  by  means  of  Powell  &  Lea- 
land's  chromatic  immersion  condenser  or  by  a  Leitz  dark-ground 
illuminator,  in  such  a  manner  that  it  is  reflected  from  the  under 
surface  of  the  cover-glass  upon  the  diatom,  then  a  pore  in  the 
centre  of  the  membrane  of  each  mesh  or  pit  is  distinctly  per- 
ceptible, and  the  structure  has  the  appearance  represented  at 
fig.  14,  which  is  drawn  by  means  of  a  camera-lucida  from  a 
portion  of  the  grating  adjoining  the  "  stauros,"  at  a  magnification 


332       N.  E.  BROWN  ON  THE  STRUCTURE  OF  DIATOMS. 

of  3,000  diameters.     The  pores  are  best  seen  when  the  light  is 
not  very  brilliant. 

Triceratium  favus. — The  structure  of  this  diatom,  as  well 
as  that  of  several  other  species,  has  been  described  and  illustrated 
in  a   very   interesting  article  by  Floegel  in  the  Journal  of  the 
Royal  Microscopical  Society,  1884,  vol.  4,  p.  665,  t.  9,  figs.  21  and 
22,  and  by  Otto  Miiller  in  the  Deutschen  Botanischen  Gesellschaft, 
1898,  vol.  16,  p.  387,  t,  26,  fig.  5,  and  1899,  vol.  17,  p.  435,  t.  29, 
figs.    1   to  5.     Both  these  authors  figure  and  describe  the  valve 
as  consisting  of  honeycomb-like  hexagonal  chambers,  which  are 
open  at  the  outer  surface  and  closed  by  a  very  thin  perforated 
plate  at  the  inner  surface  of  the  shell.      Floegel  made  sections  of 
the  valve,  and  from  his  drawings  of  what  he   saw  one  would 
expect  his  interpretation  to  be  correct.     Miiller's  interpretation 
is  substantially  the  same.     I  have  not  made  sections,  but  from 
repeated  observations  of   the  external  appearance  of   the  valve 
I  am   convinced    that    their  interpretation    is    not   correct.       If 
the  outer  surface  of  the  shell  of  T.  favus  is  examined  under  a 
binocular,  with  a  y^th  oil-immersion  objective,  using  either  oblique 
light  or   oblique  light  reflected   from   the   under  surface  of  the 
cover-glass  upon  the  object  (the  Leitz  dark-ground  illuminator, 
when  decentred,  acts  admirably  for  this  purpose),  a  thin  plate  of 
silex  closing  the  external  opening  is  very  distinctly  evident,  for 
light-reflections  and  shadows  can  be  very  clearly  seen  upon  it, 
and  are  seen  to  move  over  its  surface  when  the  mirror  is  slightly 
moved.     The  appearance  is  represented  in  fig.  15,  made  from  a 
camera-lucida  drawing,  in  which  the  outline  was  made  by  viewing 
it  under  a  monocular,  with  central  light,  at  a  magnification  of 
1,500  diameters,  and  the  shading  put  in  to  show  its  appearance 
as  seen  under  a  binocular  at  the  same  magnification  with  oblique 
light,  the  chamber  chosen  being  midway  on  the  slope  between  the 
apex  of  the  convexity  of  the  outer  surface  of  the  valve  and  the 
margin.     This  closing  membrane  I  believe  to  be  very  thin,  and 
probably  any  section  of  it  that  Floegel  made  would  be  nearly  or 
quite  invisible,  and  therefore  easily  overlooked.      I  fail  to  detect 
any  pores  in  it,  although  I  have  examined  it  by  several  methods 
of  illumination ;  but  at  the  same  time  there  is  a  faint  indication 
of  some  kind  of  fine-grained  surface  which  may  ultimately  prove 
to  be  pore-structure. 

Upon  examining  the  inner  surface  of  the  valve  at  the  same 


N.  E.  BROWN  ON  THE  STRUCTURE  OF  DIATOMS.       333 

magnification  and  with  oblique  illumination,  the  appearance  of 
the  closing  plate  is  as  shown  at  fig.  1G,  represented  for  effect  as 
at  black-dot  focus,  and  drawn  and  shaded  by  the  same  method 
as  fig.  15.     If,  however,  it  is  examined  by  dark-ground  illumi- 
nation, and  especially  if  the  illuminator  be  decentred   so   as   to 
reflect  the  light  from  the  under  surface  of  the  cover-glass  upon 
the   diatom,  the  closing  plates  appear  to  be  much  more  raised 
than  as  seen  by  oblique  light  and  nearly  hemispherical  ;  which, 
however,  is  the  correct  appearance  I  am  unable  to  say.      Both 
forms  of  illumination  distinctly  demonstrate  that  the  outer  and 
inner  closing  plates  have  their  central  part   raised   above  their 
marginal  attachment,  or,  in  other  words,   each  closing  plate   is 
separated  from  its  neighbours  by  a  furrow.     Floegel  and  Miiller, 
however,    both   represent  the  inner   plate   as    perfectly  flat   and 
even,  and  continuous  with  that  of  the  adjoining  chambers,  and  in 
their  drawings  (which  I  think  must  be  somewhat  diagrammatic) 
of  considerable  relative  thickness.     Floegel  represents  the  inner 
plate  as  containing  small  cavities  in  its  substance,  closed  on  all 
sides.     Miiller,  in  the  figure  he  published  in  1898,  represents  the 
plate  as  having  small  perforations  through  its  substance,  whilst 
in   that   published  in   1899    he   represents  the   plate   as    having 
small  concave  pits  extending  half-way  through  its  substance  on 
the  side  facing  the  interior  of  the  diatom.     This  latter  view  is, 
I  believe,  much  more  correct  than  the  other  two  interpretations, 
for  I  find  that  at  a  magnification  of  3,000  diameters,  when  the 
light  is  oblique,  or  reflected  upon  it  from  the  inner  surface  of  the 
cover-glass,  so  that  the  plate  is  of  a  dull  greyish-white  colour, 
it   is    clearly  seen   to    have    pit-like    cavities    in    it    closed    by    a 
membrane   which  is   probably  situated  at  the   other   surface  of 
the  plate.     These   pits  can   be   clearly   demonstrated   by   gently 
moving  the  mirror,  when  the  shadow  formed  by  the  wall  of  the 
pit  is  seen  to  move  round  upon  the  membrane  at  the  bottom  of 
the  pit.     The  appearance   of  the    pits    as    seen   with    the    light 
reflected  upon  them  from  the  under  surface  of  the  cover-glass  at 
a  magnification  of  3,000  diameters,  but  enlarged  to  somewhere 
about  10,000  diameters,  is  as  represented  at  fig.  17.     This  mem- 
brane under  this  form  of  illumination  is  white,  and  is  probably 
very  thin.     When  viewed  with  central  light  and  accurately  in 
focus,    it    appears    more    transparent    than    the    thicker     plate- 
substance,  and  the  light  shows  through  it  more  brightly.     But 


334  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

when  examined  under  dark-ground  illumination  the  reverse 
sterns  the  case,  for  then  the  plate-substance  appears  to  have 
the  transparent  of  a  black  sky,  and  the  membrane  of  the  pits 
reflects  the  light  so  as  to  appear  like  minute  golden  stars.  It  is 
by  some  refractive  or  diffractive  property  of  this  membrane  that 
the  black-dot  appearance  is  produced,  for  when  the  membrane 
itself  is  accurately  in  focus  no  black  dot  is  seen ;  but  if  the  focal 
plane  of  the  lens  is  above  the  focus  of  the  membrane,  then  the 
black-dot  appearance  is  produced,  and  appears  to  me  nothing 
more  than  a  deceptive  light  effect.  From  the  different  appear- 
ances of  this  membrane  under  different  methods  of  illumination 
and  its  contrast  with  that  of  the  plate,  I  think  it  must  be  of  a 
somewhat  different  nature.  Although  I  suspect  that  it  is  per- 
forated, I  have  quite  failed  to  perceive  any  trace  of  pores  in  it ; 
higher  magnification  than  I  am  able  to  obtain  is  probably  needed 
for  demonstrating  anything  of  that  nature. 

In  conclusion,  from  the  evidence  afforded  by  Mr.  Capell's  slide 
and  from  the  observations  I  have  made  upon  other  diatoms — not 
hastily  formed  opinions,  but  based  upon  many  hours'  examination 
under  all  forms  of  illumination — it  seems  clear  that  we  can  no 
longer  regard  all  the  black  dots  usually  seen  upon  diatoms  as 
being  pores  through  the  shell,  although  there  may  be  cases 
where  they  are  so  ;  for  in  the  cases  examined  they  are  certainly 
nothing  more  than  light  effects  or  shadows,  either  caused  by  the 
nodes  of  the  grating  structure,  as  in  Pleurosigma ;  or  by  the 
membrane  closing  the  meshes  of  the  grating,  as  in  Stauroneis ; 
or  by  the  membrane  closing  the  pits  in  the  cell-wall,  as  in 
Triceratium. 

What  I  take  to  be  the  true  pores  must  be  sought  for  in  the 
thin  membrane  of  silex  closing  the  meshes  or  pits.  If  these 
are  not  pores,  then  I  do  not  know  where  we  are  to  seek  for  them. 
I  think  it  must  be  perfectly  obvious,  to  all  who  like  myself  have 
carefully  studied  the  movements  of  living  diatoms,  that  there 
must  be  openings  or  pores  through  the  shell  communicating  with 
the  interior.  This  seems  also  conclusively  proved  in  cases  where 
the  shell  certainly  has  chambers  in  its  substance,  as  in  Triceratium 
favus,  Pleurosigma  angulatum  and  others,  for  in  the  ordinary 
process  of  mounting  the  medium  penetrates  easily  into  the 
interior  of  the  cavities,  and  they  can  also  be  filled  by  chemical 
deposits,  which  I  do  not  think  would  be  the  case  if  the  membranes 


N.    E.    BROWN    OX    THE    STRUCTURE    OF    DIATOMS.  335 

closing  these  cavities  were  solid,  imperforated  films  of  silex  ;  no 
osmotic  theory  will  account  for  it. 

Also  it  is  quite  certain  that  there  is  some  extrusion  of  motile 
living  matter  from  the  interior  to  the  exterior  of  the  diatom, 
which  is  controlUd  by  the  will  of  the  organism. 

No  one  has  yet  been  able  to  detect  any  protoplasmic  filaments 
or  pseudopodia   (other   than   the  crest  of   protoplasm   along  the 
raphe)  protruding  from  the  pores  of  diatoms,  and  if  they  are  as 
fine  as  the  pores  I  have  seen  would  seem  to  indicate,  and  as  trans- 
parent as  protoplasm,  I  doubt  if  we  ever  shall  see  them  on  the 
living  diatom,  as  the  nearness  of  their  own  refractive  index  to 
that  of  water  would  not  provide  sufficient  contrast  to  enable  us 
to  detect  them.       Killing   and   staining    do    not  seem  to  prove 
successful  in  demonstrating  anything  of  the  nature  of  pseudopodia, 
only  the  crest  at  the  raphe  and  a  very  thin  layer  of  protoplasm 
sometimes    covering    the    whole    shell    can    be    made   evident, 
so  far  as  I  have  been  able  to  demonstrate  it,  but  it  ought  not  to 
be  lost  sight  of  that  there  is  a  possibility  that  a  diatom  may  be 
able   to  speedily   retract   any  protoplasmic   matter  that  it  may 
protrude  from  its  shell  or  from  the  film  of  protoplasm  that  some- 
times covers  its  shell,  so  that  at  the  slightest  indication  of  the  pre- 
sence of  anything  injurious,  all  external  protoplasm  of  the  nature 
of  pseudopodia  may  be  suddenly  withdrawn  before  the  diatom  is 
killed.     Usually  there  is  no  evidence  that  any  living  matter  is 
protruded  to  any  distinct  distance  from  the  shell,  except  at  the 
raphe,  as  any  substances  taken  hold  of  by  a  diatom  are  generally 
seen  in  apparent  close  contact  with  the  shell,  although  occasionally 
one  is  seen  dragging  a  niece  of  dirt   along  at  a  short   distance 
behind  it  by  an  invisible  thread.      But  upon  a  few  rare  occasions 
I  have  witnessed  a  diatom  seize  and  move  pieces  of  dirt  that  were 
at  an  appreciable  distance  from  the  shell,  and  on  one  occasion 
last  autumn   I   was   able   to  measure  the  interval   between   the 
diatom  and  the  dirt.     I  was  observing  a  large  species  of  Surirella, 
probably  S.  biseriata,  which  was  moving  rather  quickly  across  the 
field,  when  I  saw  it  seize  with  invisible  hands  a  large  piece  of  dirt 
at  a  little  distance  from  it,  and  pull  it  along  by  its  side,  without 
decreasing  the  distance  between  itself  and  the  dirt.    I  at  once  put 
on  an  eye-piece  with  a  micrometer  scale  on  it,  and  carefully  noted 
the  distance  separating  the  dirt  and  diatom  upon  the  scale,  and 
then  substituted  a  stage  micrometer  for  the  diatom  and  found  that 


336  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

the  distance  to  which  the  pseudopodia  (if  I  may  term  them  so) 
extended  was  between  1/3, 000th  and  1/4, 000th  of  an  inch.  After 
carrying  it  along  across  about  one-third  of  the  field  of  view, 
it  released  its  hold  of  the  dirt,  and  in  doing  so  I  saw  it  give  a 
very  slight  but  distinct  jerk,  just  as  if  something  had  snapped 
suddenly,  for  the  mass  of  dirt  was  very  much  larger  than  itself. 
This  observation  was  made  with  a  fth  lens. 

Finally  a  word  as  to  the  pores.  It  must  not  be  expected  that 
they  can  be  rendered  visible  in  as  easy  a  manner  as  Surirella 
gemma  can  be  resolved  into  dots,  for  they  cannot  ;  they  are  so 
extremely  minute  that  they  are  by  no  means  easy  to  detect. 
To  make  them  out  at  all  a  Tjyth.  or  xV^n  oil-immersion  of 
1ST. A.  1*3  is  necessary,  with  eye-pieces  of  sufficient  power  to  bring 
the  magnification  up  to  at  least  1,000  diameters,  and  often  not 
less  than  2,000  diameters  is  really  required  to  make  the  structure 
clear,  combined  with  very  careful  manipulation,  a  most  exact 
arrangement  of  the  light  and  a  fair  stock  of  patience.  Some  can 
be  seen  with  central  light,  but  for  the  most  parti  have  found  that 
the  easiest  way  to  render  them  visible  is  by  means  of  a  Leitz 
dark-ground  illuminator,  from  which,  by  decentring  it,  various 
modifications  of  oblique  light  and  light  reflected  from  the  under 
surface  of  the  cover-glass  can  be  obtained.  This  method  of 
reflecting  light  upon  a  diatom  from  the  under  surface  of  the 
cover-glass  may  not  be  generally  known,  but  it  can  be  accom- 
plished by  decentring  the  condenser  or  dark-ground  illuminator, 
and  then  raising  or  lowering  it  slightly  until  the  right  effect  is 
produced.  The  process  is  not  a  difficult  operation,  but  requires  a 
little  practice,  and  very  often  features  can  be  seen  much  more 
clearly  by  this  method  than  by  any  other.  It  is  like  viewing  an 
object  upon  which  the  sun  is  shining,  with  the  back  to  the  sun. 
When  examining  a  diatom  by  means  of  the  Leitz  illuminator  no 
funnel-stop  must  be  used  in  the  lens  to  cut  down  its  aperture. 
Sometimes  a  rather  dim  light  is  better  than  a  bright  one  for 
rendering  the  structure  conspicuous. 

The  lowest  power  with  which  I  have  been  able  to  see  the  pores 
in  the  films  of  Pleurosigma  balticum  is  Powell  &  Lealand's 
excellent  |-th  water-immersion,  with  which,  in  combination  with 
a  X  18  eye-piece,  they  are  just  perceptible.  A  Leitz  ygth  or 
yg-th  oil-immersion  will  also  demonstrate  them  and  those  of 
other  species,  but  the  lens  I  have  chiefly  used  has  been  a  Iteichert 


N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS.  337 

y^th    oil-immersion    of    N.A.    1*3,    on    account    of    its    greater 
magnification,  as  it  is  really  a  xjth,  not  a  true  y^th. 

Description  of  Plate  23. 

Fig.  1.  Part  of  one  of  the  outer  films  of  the  outer  grating  of 
Pleurosigma  balticum,  x  3,000.  The  central  part  from  a  camera- 
lucida  drawing,  the  remainder  added  to  scale  from  various  parts 
of  the  films,  to  show  the  manner  in  which  the  bars  project  and 
are  held  in  place  by  the  pore-perforated  membrane  of  silex. 
Realgar  mount,  central  light,  no  stop. 

Fig.  2.  Part  of  a  curved  bar  from  a  partly  dissolved  specimen 
of  Pleurosigma  balticum,  which  presents  both  dorsal  and  edge 
views,  drawn  as  seen,  to  a  scale  of  about  9,000  diameters. 
Realgar  mount,  central  light,  no  stop. 

Fig.  3.  Part  of  the  grating  of  Swrirella  gemma,  x  3,000. 
Realgar  mount,  central  light,  no  stop. 

Fig.  4.  Four  meshes  of  the  same  enlarged  to  the  scale  of  9,000 
diameters. 

Fig.  5.  Fragment  of  the  film  overlaying  the  outer  grating  of 
Pleurosigma  angulatum,  X  3,000.  Realgar  mount,  Leitz  dark- 
ground  illuminator,  without  a  funnel-stop  at  the  back  of  the 
objective. 

Fig.  6.  Diagrammatic  enlargement  of  the  bars  of  the  film 
over  the  outer  grating  of  P.  angulatum,  to  show  the  manner  in 
which  they  appear  to  overlie  one  another,  drawn  to  a  scale 
of  6,000  diameters.  No  pores  could  be  seen  when  this  appear- 
ance is  visible. 

Fig.  7.  Outer  and  inner  grating  of  P.  angulatum  under  the 
film  of  diamond-shaped  meshes,  x  3,000.      Realgar  mount. 

Fig.  8.  Two  meshes  of  the  same  enlarged  to  9,000  diameters. 

Fig.    9.    Outer   grating    of    P.    angulatum,  seen   at  the   focus 
immediately    preceding    the    hexagonal    appearance    of    fig.    7, 
x  3,000.     Realgar  mount. 

Fig.  10.  Fragment  of  the  grating  of  Xavicula  serians,  x  3,000. 
Picric-piperine  mount ;  upper  part  showing  the  coarse  inner 
grating,  as  seen  with  central  light  and  a  central  stop  in  the  con- 
denser, green  screen  ;  lower  part  showing  the  outer  grating 
superposed  upon  the  coarser  grating,  as  seen  illuminated  by  a 
Leitz  dark-ground  illuminator^ 


338  N.    E.    BROWN    ON    THE    STRUCTURE    OF    DIATOMS. 

Fig.  1 1 .  Fragment  of  the  shell  of  Xitzschia  scalar  is,  showing 
pores,  x  3,000.     Styrax  mount,  central  light,  green  screen. 

Fig.  12.   Fragment  of  the  grating  of  Amphipleura  Lindheimeri, 
X  3,000.     Styrax  mount,  central  light,  green  screen. 

Fig.  13.  Fragment  of  the  shell  of  a  small  species  of  Pinnularia 
from  the  Cherryfielcl  deposit,  x  3,000,  showing  what  are  believed 
to  be  a  row  of  pores  down  the  centre  of  the  outer  wall  of  each 
cavity.  Picric-piperine  mount,  central  light  and  green  screen  ; 
can  also  be  seen  with  dark-ground  illumination  without  a  funnel- 
stop  in  the  lens  and  no  green  screen. 

Fig.  14.  Fragment  of  the  grating  of  Stauroneis  ])hoenicenteron, 
x  3,000.     Picric-piperine   mount,  oblique  illumination  by  Leitz 
dark-ground  illuminator. 

Fig.  15.  View  of  one  of  the  hexagonal  cavities  of  the  valve  of 
Triceratiam  favus  as  seen  from  the  outside  of  the  diatom,  showing 
the  membrane  which  closes  it  on  the  outer  side,  x  1,500.  Styrax 
mount ;  outline  drawn  with  a  camera-lucida  as  seen  under  a 
monocular,  shading  added  as  seen  under  a  binocular  with  oblique 
illumination. 

Fig.  16.  View  of  one  of  the  hexagonal  cavities  of  the  valve  of 
Triceratium  javus  as  seen  from  the  interior  of  the  diatom,  showing 
the  raised  appearance  of  the  membrane,  x  1,500.  Styrax  mount, 
drawn  in  the  same  manner  as  fig.  15. 

Fig.  17.  Fragment  of  the  membrane  shown  in  fig.  16,  drawn  as 
seen  at  a  magnification  of  3,000  diameters,  but  enlarged  to  about 
10,000  diameters,  to  show  the  pit-like  nature  of  the  dots  upon 
the  membrane. 


Joi'.m.  Qucl-ett  Microscopical  Club.  Scr.  2,  Vol.  XII.  No.  74,  April  1914. 


Jourx.  O.M.C. 

•  ♦  •  .  .  •— • — •_». 

•  •  •  #  ♦ 

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Sen  2,  Vol.  XII.,  PI.  23. 


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C       OF    CN     INCH        X      1500. 


SCALE 


1000    OF    AN     INCH      X     3000. 


N  E.  Brown,  del.  ad  nat. 


Structure  of  Diatoms. 


339 


NOTICES   OF   BOOKS. 

Handbook  of  Photomicrography.  By  H.  Lloyd  Hind,  B.Sc, 
F.I.C.,  and  W.  Brough  Randies,  B.Sc.  8|  x  5  j  in.,  xii  + 
292  pages,  44  plates  and  71  text  illustrations.  London, 
1913  :  G.  Rout  ledge  &  Sons,  Ltd.     Price  7s.  6d.  net. 

The  student  of  photomicrography,  whether  he  approach  the 
subject  from  the  side  of  photography  or  microscopy,  can  hardly 
complain  of  the  lack  of  manuals  whose  aim  is  to  guide  him 
in  this  fascinating  subject.  The  photographer,  in  reading 
Messrs.  Hind  and  Randies'  handbook,  may  perhaps  be  surprised 
that  so  much  space  is  devoted  to  details  concerning  the  micro- 
scope and  its  accessories;  but  he  must  remember  that  in  order 
to  photograph  an  object  under  the  microscope  it  is  very  essential 
he  should  possess  the  necessary  knowledge  of  the  instrument 
to  obtain  the  best  results  visually. 

Although  the  subject  is  treated  by  the  authors  in  an  ele- 
mentary manner,  at  the  same  time,  however,  the  processes  are 
discussed  in  sufficient  detail  to  be  of  use  in  research.  A  special 
feature  of  the  book  is  the  very  numerous  illustrations,  and  with 
each  photomicrograph  reproduced  full  details  are  given  of  the 
process  and  apparatus  used  and  the  method  of  developing  the 
negative.  This  very  useful  feature  enables  any  special  worker 
to  select  the  best  means  for  his  own  branch  of  the  subject, 
whether  it  be  the  photography  of  the  minute  details  of  diatoms, 
the  stained  sections  for  use  in  the  histology  of  plants  and 
animals,  or  rock  sections  and  crystals  under  polarised  light. 
The  subject  of  colour  photomicrography  is  dealt  with  in 
Chapter  XIII.  The  utility  of  the  Autochrome  and  Paget  plates 
for  registering  the  appearance  of  thin  rock  sections  under 
polarised  light  was  excellently  demonstrated  at  a  recent  meeting 
of  The  Photomicrographic  Society. 

The  subject  of  cinema-micrography  is  referred  to,  but  this 
could  hardly  be  dealt  with  fully  in  an  elementary  textbook. 
In  fact,  as  a  means  of  research  it  is  in  its  infancy,  but  fruitful 
results  may  be  expected  in  the  future  in  the  study  of  the 
life-history  and  movements  of  micro-organisms. 

There  are  useful  formulae  and  tables  at  the  end  of  the  book 
and  an  index.  Both  authors  and  publishers  may  be  congratu- 
lated on  the  appearance  of  the  book. 

Journ.  Q.  M.  C,  Series  II.— No.  74.  24 


340 


PROCEEDINGS 

OF    THE 

QUEKETT    MICROSCOPICAL  CLUB. 

At  the  492nd  ordinary  meeting  of  the  Club,  held  on  October  28th, 
1913,  the  President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair, 
the  minutes  of  the  meeting  held  on  June  24th,  1913,  were  read 
and  confirmed. 

Mr.  S.  G.  H.  Knox  was  balloted  for  and  duly  elected  a  member 
of  the  Club. 

The  Hon.  Secretary  said  they  were  favoured  with  the  presence 
of  several  visitors,  to  whom  he  offered  a  hearty  welcome  on  behalf 
of  the  Club. 

The  President  said  that  members  would  be  sorry  to  hear  that 
since  the  last  ordinary  meeting  the  Club  has  sustained  the  loss  of 
one  of  our  more  well-known  members  :  the  Right  Hon.  Sir  Ford 
North,  F.R.S.,  died  on  October  12th,  at  the  age  of  eighty-three. 
He  was  a  Fellow  of  the  Royal  Society,  and  a  keen  entomologist. 
He  was  elected  a  member  of  the  Club  in  1894,  became  a  member 
of  the  committee  in  1899,  and  was  one  of  the  vice-presidents  from 
February  1901.  His  patience  and  experience  in  directing  a 
meeting  when  he  occupied  the  chair  made  him  a  most  valuable 
member  of  the  Club,  and  one  whose  loss  will  be  much  regretted. 

Mr.  E.  J.  Spitta  said  that  Sir  Ford  North  hardly  ever  missed 
attending  the  meetings  of  the  Club,  and  he  thought  that  a  more 
charming  man  never  existed.  Often  in  committee  he  would 
remain  silent  for  a  long  time,  and  would  then  rap  out  a  very 
clever  opinion  on  the  matter  before  them.  During  the  four  years 
of  his  (Mr.  Spitta's)  presidency  he  had  frequent  opportunities  of 
intercourse  with  Sir  Ford  North,  and  on  every  occasion  had  found 
him  a  courteous  friend. 

Mr.  Spitta  then  moved:  "That  the  Committee  be  empowered 
through  the  Secretary  to  convey  to  the  relatives  of  the  late  Sir 
Ford  North  an  expression  of  their  regret  and  sympathy." 

This  having  been  put  to  the  meeting,  it  was  unanimously 
carried  by  the  members  present  silently  rising. 


PROCEEDINGS    OF   THE    QUEKETT    MICROSCOPICAL    CLUB.         341 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks  of 
the  members  were  voted  to  the  donors. 

Mr.  S.  C.  Akehurst  (Hon.  librarian)  read  a  note  on  "A 
Changer  for  Use  with  Sub-stage  Condensers."  The  method  of 
using  the  changer  was  demonstrated  to  the  members. 

Mr.  S.  C.  Akehurst  also  read  a  note  on  "  A  Trap  for  Free- 
swimming  Organisms."  Two  forms  of  the  little  piece  of  apparatus 
were  exhibited,  and  details  demonstrated  by  drawings  on  the 
blackboard. 

The  President  said  he  had  examined  the  extremely  ingenious 
contrivance  for  quickly  changing  the  condenser.  It  was  a  matter 
which  very  strongly  appealed  to  him,  as  he  had  often  much 
trouble  in  changing  condensers. 

Mr.  D.  J.  Scourfield,  referring  to  the  trap  for  free-swimming 
organisms,  said  this  method  opened  new  possibilities  wThen 
dealing  with  extremely  minute  organisms.  One  can  get  to  a 
certain  point  with  the  centrifuge  ;  but  it  is  sometimes  desired  to 
go  a  little  further  in  concentrating.  He  thought  it  a  very 
ingenious  piece  of  apparatus. 

A  paper  on  "  The  Gastrotricha,"  communicated  by  Mr.  James 
Murray,  F.R.S.E.,  was  introduced  by  Mr.  Scourfield,  who  said 
that  it  was  just  twenty-four  years  since  the  subject  had  pre- 
viously been  brought  before  the  notice  of  the  Club.  This  was 
a  paper  read  by  T.  Spencer  on  September  27,  1889,  on  a  new 
species  he  provisionally  named  Polyarthra  fasiforniis.  This  is 
now  Stylochaeta  fusiformis.  Mi1.  Murray  said  that  he  had 
been  reluctant  to  attempt  an  introduction  to  the  study  of  the 
Gastrotricha,  as  his  knowledge  of  the  group  was  by  no  means 
profound,  and  had  been  only  recently  acquired.  The  main  part 
of  the  paper  is  an  annotated  bibliography  which  it  was  hoped 
would  save  students  much  of  the  trouble  the  author  had  ex- 
perienced. If  the  bibliography  be  too  condensed,  the  student  is 
always  liable  to  suspect  that  a  work  omitted  from  it  has  not 
come  to  the  knowledge  of  the  compiler.  Here,  however,  all 
important  general,  biological  and  systematic  works  known  to 
the  author  are  included,  as  well  as  any  really  important 
faunistic  studies.  Every  work  is  given  in  which  new,  or  sup- 
posed new,  species  or  groups  of  higher  value  are  described.  It 
is  unfortunate  that  the  Gastrotricha — which  include  those  old 
familiar  friends  of  the  students  of  pond-life,   Chaetonotus   lanes 


342  PROCEEDINGS    OF    THE 

and    Ichthydium  podura — have  no  popular   name.       Gosse    pro- 
posed the  name  of  "  hairy-backed  animalcules."     This  is  entirely 
unsuitable,    since    some    of    the    genera    are    not     hairy-backed 
(Ichthydium,  Lepidoderma).     Mr.  Murray  was  not  able  to  suggest 
an   appropriate    name.     The   name    suggested  by  the  scientific 
term    for    the  whole    group,  which    embodies    almost    the    only 
character  which  they  all  possess,  is  unsuitable  for  popular  use. 
The  Gastrotricha  are  not  animals  which  can  be  named  offhand. 
The   days    when    we    found  Chaetonotus    lanes   and    Ichthydium 
podura,  occasionally  varied  by  C.  maximus,  on  all  our  pond-life 
excursions    are    over.      There   is    a    host   of  species   which  have 
contributed  to  the  records  of  C.    larus.     These    species    are    all 
alike    to    a    casual    glance,    but    are    distinguished    by    minute 
characters — the    possession  of  small  branches  by  certain  of  the 
bristles,  the  form  of  the  minute  scales  which  bear  the  bristles, 
etc.     Some  of   these  are  so  delicate  that  an  oil-immersion  lens 
would  be  needed  for  their  certain  determination.      The    author 
expressed  his  thanks  to  Messrs.  Rousselet,  Bryce  and  Starring 
for  assistance  given  in  the  preparation  of  this  paper.     The  paper 
then  goes  on  to  describe  the  form  and  structure  of  the  Gastro- 
tricha, their  haunts    and    habits,    an    historical    sketch    of    the 
genera,   their  classification,  a  key  to  the   genera   and    a   list   of 
the  eighty-three  species  which  have  been  described,  notes  on  the 
identification  of  species  and  on  some  species  Mr.  Murray  had  seen, 
and   concludes   with   a   bibliography  of  seventy-two  items.     Mr. 
Scourfield  illustrated  his  remarks  and  comments  by  references  to 
a  number  of  sketches  he  had  drawn  on  the  blackboard. 

The  President  had  much  appreciated  Mr.  Scourfield's  resume 
of  Mr.  Murray's  paper.  He  referred  to  the  "  fish-hook  "  spines 
and  other  extraordinary  specific  characters,  which,  he  thought, 
could  not  possibly  be  explained  as  due  to  natural  selection.  The 
Club  was  very  much  to  be  congratulated  on  having  such  an 
important  paper  contributed  to  the  Journal. 

Mr.  llousselet  said  these  organisms  could  be  preserved  quite 
well  in  5-per-cent.  formalin.  He  remembered  Mr.  Spencer's 
paper  in  1889  quite  well,  and  had  differed  from  him  at  the 
time,  and  had  said  fusiformis  was  not  a  rotifer,  but  could 
not  then  say  what  it  was.  The  animal  was  taken  at  a  Club 
excursion. 

On  the  motion  of  the  President  a  cordial  vote  of  thanks  was 


QUEKETT    MICROSCOPICAL    CLUB.  343 

passed  to  Mr.   Murray  for  his  paper  and  to  Mr.   Scourfield  for 
giving  them  so  good  a  resume  of  it. 

Mr.  James  Grundy  described  and  exhibited  "An  Improved 
Form  of  Cheshire's  Apertometer." 

Mr.  Grundy  said  that  of  the  value  of  Mr.  Cheshire's  form  of 
apertometer  there  can  be  no  doubt.  The  aim  of  Mr.  Nelson  has 
been  to  enable  the  N.A.  values  of  an  objective  to  be  read  on  the 
apertometer  easily  and  accurately.  Distinctness  and  clearness  of 
reading  have  been  effected  by  increasing  the  number  of  marked 
values  of  N.A.  from  9  to  22  without  the  confusion  that  over- 
crowding of  the  lines  would  entail.  To  accomplish  this,  short 
arcs  of  circles  are  used  instead  of  whole  circles.  A  valuable  pro- 
perty of  these  is  the  clear  visibility  of  the  ends  or  edges  of  the 
arcs  :  they  are  seen  more  distinctly  than  complete  circles  would 
be.  The  contrast  between  the  white  ground  and  the  short  black 
lines  favours  this.  The  exterior  edges  of  the  arcs  denote  the  N.A., 
and  thus  give  most  convenient,  accurate,  and  definite  positions  for 
reading. 

Mr.  F.  J.  Cheshire  said  it  might  interest  members  to  know 
that  he  described  his  apertometer  before  the  Club  some  ten  years 
ago.  When  Zeiss  first  issued  Abbe's  form,  it  was  marked  to  read 
only  to  005.  In  a  paper  defending  this  marking,  read  before  the 
R.M.S.  in  1880,  Abbe  dealt  with  the  accuracy  it  was  necessary 
to  strive  for.  On  the  Zeiss  apertometer  it  is  possible  to  read  to 
|  per  cent. ;  but  blue  rays  alone  will  give  a  difference  of  1  per 
cent,  over  a  reading  taken  with  red  light,  so  that  the  maximum 
accuracy  it  was  advisable  to  attempt  to  obtain  was  1  per  cent. 
Mr.  Cheshire  thought  that  one  point  in  Mr.  Nelson's  diagram 
largely  vitiates  the  advantages  given  by  a  greater  number  of 
fiducial  Hues — that  is,  that  the  fiducial  edge  in  the  diagram  is 
the  outer  edge  of  the  line  ;  and,  again,  the  lines  are  of  varying 
thickness.  There  are  twenty-two  edges  of  lines  on  the  diagram 
with  no  fiducial  value.  He  himself  thought  that  his  original 
form  was  not  capable  of  further  accuracy.  Mr.  Cheshire  then 
described,  and  subsequently  demonstrated,  another  method  of 
measuring  N.A.,  which  he  considered  an  improvement  on  the 
older  form. 

A  visitor — Mr.  M.  A.  Ainslie,  K.N. — said  that  experience  in 
the  use  of  both  the  original  form  of  Cheshire's  apertometer  and 
the  modification  thereof  recently  suggested  by  Mr.  Nelson  has 


344  PROCEEDINGS    OF    THE 

revealed  one  or  two  difficulties  in  connection  with  the  reading  of 
the  instrument — that  is,  if  any  accuracy  in  the  second  decimal 
place  is  required.  The  first  difficulty  is  due  to  the  fact  that  in 
Mr.  Cheshire's  instrument  we  have  to  interpolate  or  estimate 
between  two  divisions  on  a  scale,  one  of  which  is  not  visible,  being 
outside  (apparently)  the  margin  of  the  back  lens  of  the  objective. 
This  renders  the  estimation  of  the  second  place  of  decimals  in  the 
N.A.  uncertain,'  and  although  Mr.  Nelson's  modification  of  the 
original  instrument  is  somewhat  better  in  this  respect,  yet  the 
very  means  adopted  to  improve  the  reading — namely,  the  intro- 
duction of  a  large  number  of  additional  circles — is  likely  to  con- 
fuse the  diagram  and  bewilder  the  observer.  In  either  the  old 
form  or  the  new  of  Cheshire's  instrument,  a  count  has  to  be  made 
of  concentric  circles — a  thing  which,  simple  as  it  may  seem,  is 
peculiarly  liable  to  confuse  the  eye,  so  that  it  is  only  after  count- 
ing several  times  that  one  feels  certain  that  the  number  is,  say, 
eight,  and  not  seven. 

Mr.  Ainslie  exhibited  and  described  a  new  method  of  reading 
the  N.A.  of  an  objective, 

The  President  said  the  Club  was  much  indebted  to  Mr.  Ainslie 
for  his  communication,  and  also  to  Mr.  Cheshire  and  Mr.  Grundy, 
to  whom  the  thanks  of  the  meeting  were  unanimously  voted. 


At  the  493rd  ordinary  meeting  of  the  Club,  held  on  Novem- 
ber 25th,  1913,  the  President,  Prof.  A.  Dendy,  D.Sc.,  F.R.S., 
in  the  chair,  the  minutes  of  the  meeting  held  on  October  28th, 
1913,  were  read  and  confirmed. 

Messrs.  W.  M.  Bale,  B.  Shepherd,  H.  Dobell,  E.  W.  Ramsay, 
M.  R.  Licldon,  A.  Panichelli,  Robert  Young,  W.  G.  Tilling,  and 
E.  J.  E.  Creese  were  balloted  for  and  duly  elected  members  of 
the  Club. 

The  President  read  a  letter  from  the  nephew  of  the  late  Sir 
Ford  North,  which  was  in  reply  to  the  vote  of  sympathy  passed 
at  the  last  meeting. 

Mr.  C.  E.  Heath,  F.R.M.S.,  brought  before  the  notice  of  the 
meeting  a  device  for  preventing  damage  to  objective  or  slide, 
especially  when  the  higher  powers  are  used,  in  cases  where  the 
microscope  is  liable  to  unskilful  usage,  as,  e.g.,  at  soirees.  A 
small  piece  of  thin  metal — steel  was  suggested — is  taken,  having 


QUEKETT    MICROSCOPICAL    CLUB.  345 

a  hole  in  it  of  such  a  size  as  to  permit  of  the  screw-end  of  an 
objective  passing  through  it  up  to  its  flange.  In  use  the  plate  is 
placed  over  the  end  of  the  nose-piece,  and  the  objective  screwed 
home  through  it.  To  a  projecting  portion  of  the  metal  plate  is 
fitted  a  short  length  of  brass  tube  or  rod — say  |  in.  diameter, 
which  has  been  tapped  internally,  the  direction  of  the  tube  being 
parallel  to  the  optic  axis,  and  just  clear  of  the  objective.  A  fine 
screw  (25  threads  to  an  inch)  is  fitted  to  the  tube,  and  at  the 
lower  end  is  provided  with  a  milled  head.  The  microscope  is 
focused  in  the  usual  way,  and  the  screw  then  screwed  down  until 
it  is  in  contact  with  the  stage  clear  of  the  cover-glass,  and  so 
prevents  any  movement  of  the  body,  and  possible  damage.  If 
required,  a  small  amount  of  slack  may  be  left  for  possible  focusing 
by  visitors  who  can  use  a  microscope. 

The  President  described  "  A  Red- Water  Phenomenon  due  to 
Euglena."  He  had  noticed  a  curious  appearance  in  a  pond  near 
Manchester :  the  water  was  of  a  brilliant  red  colour.  This,  on 
examination,  proved  to  be  due  to  Euglena,  which  formed  quite  a 
thick  scum  of  the  red  colour.  The  colour  was  confined  to  the 
surface,  and  had  a  dry,  powdery  appearance  that  was  very  notice- 
able. Microscopic  examination  showed  the  Euglena  to  be  of  a 
large  species,  and  the  red  coloration  to  be  due  to  the  replace- 
ment of  the  chlorophyll  by  haematochrome.  The  main  mass  of 
the  body  was  coloured.  Those  floating  on  the  surface  were  in  a 
resting  condition  ;  but,  at  the  bottom,  all  were  actively  swimming 
about.  There  was  apparently  no  intermediate  stage,  and  at  once 
the  question  arose  :  How  did  the  organisms  get  from  the  bottom 
to  the  top  of  the  pond  %  It  was  found  that  the  Euglenae  at  the 
bottom  of  the  pond  secreted  large  quantities  of  mucilage.  The 
organism,  in  the  presence  of  sunlight,  gave  off  bubbles  of  oxygen, 
which  became  entangled  in  the  mass  of  mucilage,  and  presently 
carried  the  mass  to  the  surface,  trailing  Euglenae  after  it,  so  that 
they  were  collected  at,  and  formed  a  scum  on,  the  surface.  The 
colour  of  the  scum  changed  during  the  day,  from  red  in  the 
morning  to  green  in  the  afternoon,  the  actual  change  from  one  to 
the  other  being  accomplished  in  about  half  an  hour.  Cunning- 
ham had  observed  similar  changes  in  Euglena  viridis,  near 
Calcutta,  lie  records  the  scum  as  bright  red  in  the  morning 
dull  red  at  midday,  and  green  in  the  evening,  and  by  sunset  an 
intensely  vivid  green.     The  reverse  took  place  just  about  dawn, 


346  PROCEEDINGS    OF    THE 

so  that  at  sunrise  the  pond  scum  was  brilliant  red  again.     The 
President  asked  if  any  members  had  seen  a  similar  appearance. 

Mr.  C.  F.  Rousselet,  when  in  South  Africa  with  the  British 
Association  in  1905,  had  noted  near  the  Matoppo  hills  a  similar 
red  Euglena,  which  he  had  not  before  seen. 

The  Hon.  Sec.  paid  considerable  attention  to  the  "  Breaking  of 
the  Meres,"  but  had  never  seen  red  Euglena.  He  had  observed 
red  scum,  due  to  other  causes.  The  phenomenon  noticed  by  the 
President  was,  however,  not  unique  in  this  country.  Some  years 
ago  he  had  received  some  "  red  scum  "  material  from  Norfolk, 
which  was  definitely  identified  as  Euglena.  The  organisms  were 
crowded  in  their  middle  region  with  starch  grains,  and  starch  in 
such  a  form  that  it  was  not  affected  by  iodine. 

Mr.  A.  E.  Hilton  asked  whether  the  red  colour  indicated  the 
decay  of  the  chlorophyll  formed  during  the  previous  day. 

The  President  did  not  think  that  the  change  from  green  to  red 
indicated  any  process  of  decay — this  change  of  colour  was  not 
unique  in  Nature,  as  the  snow  plant  could  be  obtained  both  red 
and  green,  and  apparently  the  change  was  due  to  nitrogen  starva- 
tion. He  found  this  to  be  the  probable  cause  when  he  had  two 
jars  side  by  side,  one  red  and  the  other  green,  and  a  fly  had 
fallen  into  one  jar  and  had  decayed  ;  the  slightest  trace  of  nitro- 
genous food  was  sufficient  to  cause  the  change,  which  he  thought 
could  not  be  regarded  as  a  product  of  decomposition.  Dr. 
Cunningham  thought  that  both  kinds  of  pigment  were  present  at 
the  same  time,  but  that  they  were  differently  placed  when  the 
change  of  colour  was  observed  ;  but  whether  this  was  the  sole 
reason  for  the  change  in  the  Euglenae  was  not  certain. 

Mr.  James  Burton  (Hon.  Secretary)  read  a  short  paper, 
"  On  the  Disc-like  Termination  of  the  Flagellum  in  certain 
Euglenae." 

Mr.  James  Burton  also  read  a  note  on  "  A  Method  of  Marking 
a  Given  Object  on  a  Mounted  Slide." 

Mr.  M.  Blood  said  he  usually  put  a  spot  of  ink  on  the  bright 
spot  of  light  formed  on  the  slide  by  a  high-power  condenser,  and 
when  it  was  dry,  scraped  the  centre  away. 

Mr.  Spitta,  after  finding  and  centring  the  object  in  the  field, 
replaced  the  objective  with  a  dummy  of  similar  size,  on  to  the  lower 
end  of  which  had  been  fastened  a  rubber  letter  0,  such  as  is  to  be 
obtained  in   small  movable-type  printing  outfits.     The  letter  is. 


QUEKETT    MICROSCOPICAL    CLUB.  347 

inked,  and  gently  lowered  on  to  the  slide.  He  had  found  this 
method  quite  satisfactory. 

Mr.  James  Grundy  read  a  paper  communicated  by  Mr.  E.  M. 
Nelson  on  "  The  Measurement  of  the  Initial  Magnifying  Powers 
of  Objectives."  Mr.  Grundy  added  a  few  notes  in  amplification 
and  explanation  of  some  points  in  Mr.  Nelson's  paper,  which  he 
illustrated  with  blackboard  diagrams. 

A  vote  of  thanks  to  Mr.  Grundy  was  carried  unanimously. 


At  the  494th  ordinary  meeting  of  the  Club,  held  on  December 
23rd,  1913,  Mr.  D.  J.  Scourfield,  F.Z.S.,  F.R.M.S.,  Vice- 
President,  in  the  chair,  the  minutes  of  the  meeting  held  on 
November  25th,   1913,  were  read  and  confirmed. 

Messrs.  M.  A.  Ainslie,  R.  A.  Saunders,  T.  B.  Lock,  F.  S. 
Mumford,  A.  Green,  H.  F.  W.  Sprenger,  W.  D.  Deed  and  J.  H. 
North  were  balloted  for  and  duly  elected  members  of  the  Club. 

A  letter  was  read  from  the  Poyal  Microscopical  Society 
enclosing  a  copy  of  a  resolution  passed  by  their  Council,  thanking 
the  members  of  the  Q.M.C.  who  exhibited  at  their  Conversazione 
on  November  19th. 

Mr.  B.  M.  Draper  read  a  paper  on  a  new  live  box  for  the 
exhibition  of  flies  and  other  large  objects  under  low  powers  of  the 
microscope — the  article  itself  being  exhibited  in  the  room  under  a 
Greenhough  binocular. 

Mr.  B.  M.  Draper  also  read  a  paper  describing  a  new  stop  for 
obtaining  dark-ground  illumination  with  the  Greenhough 
binocular — the  subject  being  illustrated  by  the  exhibition  of  the 
stop  and  by  a  diagram  upon  the  blackboard. 

The  Chairman  thought  the  live  box  well  adapted  for  showing 
large  objects,  and  inquired  if  any  means  were  adopted  for  con- 
fining the  insects  or  controlling  their  movements  whilst  under 
observation. 

Mr.  Draper  said  there  was  no  other  means  of  controlling  the 
movement  of  the  objects  except  by  the  use  of  a  small  cell,  but 
the  power  used  being  a  low  one,  the  whole  cell  was  generally  in 
the  field  at  the  same  time ;  and  in  answer  to  a  question  by 
Mr.  Rousselet,  he  said  that  the  cover  of  the  cell  was  only  held 
down  by  its  own  weight,  but  it  was  prevented  from  slipping 
sideways  by  the  upright  pins  mentioned  in  the  paper. 


q 


48  PROCEEDINGS    OF    THE 


The  thanks  of  the  meeting  were  voted  to  Mr.  Draper  for  his 
papers. 

Mr.  W.  R.  Traviss  exhibited  under  microscopes  two  fragments 
of  quartz  crystals.  Referring  to  one  of  the  mounts,  he  said  it 
showed  a  series  of  seven  faint  lines  across  the  field,  parallel,  but 
not  equally  spaced.  He  suggested  that  the  lines  at  one  time 
were  respectively  the  outer  surfaces  of  the  crystal.  The  plane 
of  this  particular  surface  in  the  mount  referred  to  was  at  right 
angles  to  the  plane  of  the  microscope  stage,  so  that  by  focusing 
down  one  could  look  along  this  plane.  It  was  then  noted  that 
this  "  old  crystal  surface  "  was  covered  with  a  number  of  very 
small  crystals,  or  debris,  which  had  been  deposited  on  this  plane. 
Presently  the  crystal  went  on  growing,  and  again  a  period  of  rest 
and  more  debris  deposited  or  formed.  This  was  repeated  seven 
times,  but  the  exterior  face  was  quite  smooth. 

Then  as  to  the  occasional  presence  of  contained  bubbles  of 
liquid  in  quartz  (and  other)  crystals.  It  was  suggested  that  it 
was  possible  that  they  were  formed  by  a  bubble  of  gas  adhering 
to  perhaps  the  under  surface  of  a  growing  crystal,  and  material 
being  deposited  round  and  over  it. 

Some  discussion  followed  on  liquid  enclosures  in  crystals  and 
the  nature  and  method  of  identification  of  the  gases  contained. 
The  chairman  drew  attention  to  a  paper  by  Mr.  Ashe  on  the 
effects  of  temperature  on  enclosed  liquids.  (Journ.  Q.  M.  C,  Ser. 
2,  Vol.  VIII.,  pp.  545-8,  pi.  28.) 

Mr.  E.  M.  Nelson  sent  a  note  on  a  peculiar  form  of  diatom. 
During  an  examination  with  dark-ground  illumination  of  Mr. 
Siddall's  filaments  on  some  Coscinodisci  in  a  diatom  gathering, 
mounted  and  kindly  given  me  by  Mr.  Chaffey,  a  small  portion 
of  sandy  grit  was  found  to  have  similar  filaments  protruding  from 
it.  Its  colour  was  a  golden  yellow,  the  same  as  the  sandy  grit 
usually  seen  in  this  kind  of  slide,  which  contains  diatoms  mounted 
in  sea-water  in  their  natural  state.  The  dark-ground  illumi- 
nator was  removed,  and  when  the  object  was  examined  by  an 
oil-immersion  gth  with  transmitted  light  from  an  achromatic 
condenser,  the  green  chlorophyll  pustules  of  a  diatom  could  just 
be  made  out  inside  the  conglomerated  mass  of  sandy  grit.  A 
search  was  then  made  over  the  slide,  and  three  or  four  other 
similar  specimens  were  found.  So  it  appears,  then,  that  there  is 
a  "  caddis-worm  "  form  of  a  diatom.     What  species  this    diatom 


QUEKETT    MICROSCOPICAL    CLUB.  349 

may  be  no  one  can  say,  for  it  cannot  be  seen  with  sufficient  dis- 
tinctness for  identification.  Probably  in  its  cleaned  state  it  may 
be  a  very  common  and  well-known  form,  but  had  it  not  been  for 
its  filaments,  its  presence  in  these  sandy  conglomerations  would 
never  have  been  suspected.  Other  species  of  diatoms  on  this  slide 
were  quite  free  from  sandy  grit. 

Mr.  Nelson  ako  sent  a  note  on  Amphipleura  Lindheimeri. 


At  the  495th  ordinary  meeting  of  the  Club,  held  on  January 
27th,  the  President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the 
chair,  the  minutes  of  the  meeting  held  on  December  23rd,  1913, 
were  read  and  confirmed. 

Messrs.  H.  A.  Gee,  G.  H.  Shelley,  A.  Walker,  the  Rev.  G.  H. 
Nail,  Lieut.-Col.  J.  Clibborn  and  L.  E.  Harris  were  balloted  for 
and  duly  elected  members  of  the  Club. 

The  list  of  nominations  by  the  Committee  of  officers  for  the 
ensuing  year  was  then  made — there  being  no  change  from  that 
elected  last  year. 

The  President  having  mentioned  that  four  members  of  the 
Committee — Messrs.  Wilson,  Heron- Allen,  Bryce  and  Caffyn  — 
would  retire  by  rotation,  but  were  eligible  for  re-election,  except 
Mr.  Caffyn,  who  did  not  wish  to  serve  again,  asked  for  nomina- 
tions of  members  to  fill  the  vacancies  created. 

The  following  gentlemen  were  thereupon  nominated  :  Messrs. 
Heron -Allen,  Wilson,  Bryce,  Gabb,  A.  Morley  Jones  and  Todd, 
whose  names  would  appear  on  the  voting  paper  at  the  next 
ordinary   meeting. 

Mr.  A.  E.  Hilton  was  then  elected  as  Auditor  on  behalf  of  the 
members. 

Mr.  S.  C.  Akehurst  (Hon.  Librarian)  read  "  Some  Remarks  on 
Sub-stage  Illumination  "  ;  the  subject  was  illustrated  by  a  number 
of  photographs  projected  upon  the  screen. 

Mr.  T.  A.  O'Donohoe  read  a  paper,  entitled  "An  Attempt  to 
resolve  Pinnularia  nobilis"  This  was  illustrated  by  photographs 
projected  upon  the  screen. 

Mr.  M.  A.  Ainslie  said  that  the  whole  question  of  diffraction 
spectra  was  of  course  of  vital  importance  in  the  resolution  of  any 
fine  structure,  and  in  many  cases  it  could  not  be  done  with  a  dry 
lens.     By  means  of  diagrams  drawn  on  the  blackboard  as  he  pro- 


350  PROCEEDINGS    OF    THE 

ceeded,  the  speaker  showed  the  effects  of  diffraction  spectra  under 
varied  conditions.  In  using  annular  illumination  they  were 
using  a  number  of  central  cones  of  illumination  overlapping  to 
form  the  annular.  He  also  pointed  out  the  danger  of  using 
annular  illumination  unless  great  care  was  exercised  as  to  the 
tube  length. 

Mr.  Blood  said  it  was  extremely  easy  to  resolve  diatoms  with  a 
central  stop — in  which  case  they  were  merely  seeing  the  image  of 
the  stop.  In  many  objectives  the  central  portion  and  the 
extreme  edge  were  over  corrected,  but  the  intermediate  zone  was 
quite  right. 

Mr.  Brown  said  he  had  been  examining  Pinnularia  nobilis  for 
the  last  forty  years,  and  thought  he  had  obtained  a  resolution  of 
it,  but  not  the  same  as  that  described  by  Mr.  O'Donohoe.  For  a 
long  time  he  was  unable  to  get  any  resolution,  but  he  believed  he 
had  now  done  so,  and  hoped  shortly  to  read  a  paper  on  the  subject. 

Mr.  Akehurst  explained  that  the  photographs  shown  in  illus- 
tration of  his  paper  were  taken  to  show  the  contrast  between  the 
ordinary  and  the  new  method  of  illumination  with  central  stop 
below  the  condenser,  but  without  cutting  down  the  N.A.  of  the 
objective. 

Votes  of  thanks  were  cordially  passed  to  Mr.  Akehurst  and 
Mr.  O'Donohoe  for  their  papers. 

In  place  of  the  usual  monthly  conversational  meeting,  a  Conver- 
sazione was  held  on  February  10th,  in  the  Great  Hall,  King's 
College,  by  kind  permission  of  the  Principal.  Nearly  five  hundred 
members  and  visitors  were  present,  and  about  170  microscopes, 
besides  other  apparatus,  were  on  exhibition.  It  is  not  possible  to 
give  a  complete  list  of  the  objects  shown  ;  but  among  others  may 
be  mentioned  a  number  of  coloured  drawings  of  water-mites, 
including  a  series  of  fifteen  figures  illustrating  the  life-history  of 
Hydrachna  ylobosa  (de  Geer),  by  C.  D.  Soar  ;  foraminifera  under 
microscopes,  and  material  from  the  sea-bottom  in  various  stages 
of  preparation,  by  Messrs.  Heron-Allen  and  Earland ;  living- 
rotifers  by  Messrs.  Bryce,  Dunstall,  Rousselet,  Scourfield  and 
others ;  stereophoto-micrographs  by  Messrs.  A,  E.  Smith  and 
Taverner  ;  photomicrographic  apparatus  and  some  sixty  natural- 
colour  lantern-slides  by  E.  Cuzner  ;  some  fine  photomicrographs 
in  colour  of  polarised  rock  sections  by  Messrs.  Cafiyn  and  Ogilvy. 


QUEKETT    MICROSCOPICAL    CLUB.  351 

Mr.  H.  F.  Angus  (H.  F.  Angus  &  Co.)  showed  the  Reichert 
demonstration  and  comparison  eye-piece  for  comparing  the  fields 
from  two  microscopes  in  one  eye-piece,  in  which  the  field  is  divided 
laterally,  Akehurst's  phototropic  pond-life  trap,  Draper's  all-glass 
live  box,  the  Finlayson  revolving  disc  for  the  exhibition  of  a 
series  of  opaque  objects,  Heath's  objective-guard,  etc. 

Mr.  Lees  dirties  (C.  Baker)  had  on  view  several  Greenhough 
binocular  microscopes,  multicolour  illumination  of  crystals,  and 
three  forms  of  the  Cheshire  apertometer. 

Mr.  C.  Beck  (R.  &  J.  Beck)  exhibited  the  new  model  high- 
power  binocular,  employing  a  -jVth  oil-immersion  objective,  with 
a  very  simple  and  efficient  adjustment  for  inter-pupillary 
distance. 

Mr.  J.  W.  Ogilvy  (E.  Leitz)  showed  several  new  short-tube 
high-power  binoculars  employing  a  TVth  oil-immersion  objective ; 
a  comparison  eye-piece  for  comparing  simultaneously  complete 
fields  of  two  microscopes;  and  several  examples  of  the  Green- 
hough  binocular — one   especially  adapted  for  metallurgical  work. 

Mr.  F.  W.  W.  Baker  (W.  Watson  &  Sons)  exhibited  a  new 
model  Yan  Heurck,  with  2|  in.  movement  to  the  stage,  and 
complete  rotation,  also  a  new  workshop  metallurgical  microscope 
and  some  twenty  microscopes  with  various  objects,  including  a 
series  of  seven  illustrating  the  development  of  the  chick  from 
twenty-four  hours  to  four  clays. 

During  the  evening  a  lantern  lecture  was  given  in  the  large 
theatre  by  Mr.  F.  W.  Watson  Baker  (Watson  &  Sons)  on  "  Some 
Microscopical  Hows,"  and  subsequently  Mr.  C.  Lees  dirties 
(C.  Baker)  gave  a  lantern  demonstration,  in  the  same  place,  of 
natural-colour  photographs  and  photomicrographs  of  miscellaneous 
and  microscopic  objects  prepared  by  the  Paget  process.  Both 
lectures  were  well  attended  and  much  appreciated. 

Of  late  years  the  club  has  not  held  conversaziones,  and  during 
the  evening  the  wish  was  several  times  expressed  that  such 
gatherings  should  be  more  frequent,  and  certainly  that  no  long 
interval  should  elapse  between  this  and  the  next.  (The  last 
conversazione  was  held  nearly  seventeen  years  ago — on  May  4th, 
1897 — in  the  smaller  Queen's  Hall.) 


352 


PROCEEDINGS    OF    THE 


At  the  496th  ordinary  meeting  of  the  Club  held  on  February 
24th,  which  was  also  the  forty-eighth  annual  general  meeting, 
the  President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair  the 
minutes  of  the  meeting  held  on  January  27th  were  read  and 
confirmed. 

Messrs.  A.  0.  Gooding  and  Raymond  Finlayson  were  balloted 
for  and  duly  elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  were  read,  and  the  thanks  of 
the  members  voted  to  the  donors. 

Mr.  N.  E.  Brown  and  Mr.  F.  W.  Watson  Baker  having  been 
appointed  scrutineers,  the  ballot  for  the  election  of  officers  and 
Council  for  the  ensuing  year  was  proceeded  with  ;  it  being  sub- 
sequently announced  that  the  following  gentlemen  had  been 
elected  as 


President 


•  •  • 


Four 
Vice-Presidents 

Treasurer 
Secretary 

Assistant  Secretary 
Foreign  Secretary  . 
Reporter  .... 
Librarian  .  .  . 
Curator  .... 
Editor     .... 

Four  Members  of 
Committee. 


Prof.  Arthur  Dendy,  D.Sc,  F.R.S. 

C.  F.  Rousselet,  F.R.M.S. 

E.  J.  Spitta,  L.R.C.P.,  M.R.C.S.,  F.R.A.S 

D.  J.  Scourfield,  F.Z.S.,  F.R.M.S. 
IProf.  E.  A.  Minchin,  M.A.,  Ph.D.,  F.R.S. 

Frederick  J.  Perks. 
James  Burton. 
J.  H.  Pledge,  F.R.M.S. 
C.  F.  Rousselet,  F.R.M.S. 
R.  T.   Lewis,  F.R.M.S. 
S.  C.  Akehurst,  F.R.M.S. 

C.  J.  Sidwell,  F.R.M.S. 

A.  W.  Sheppard,  F.Z.S.,  F.R.M.S. 
(A.  Morley  Jones. 

E.  Heron-Allen,  F.L.S.,  F.Z.S.,  F.R.M.S. 
J.  Wilson,  F.R.M.S. 

D.  Bryce. 


The  Hon.  Secretary  read  the  Committee's  forty-eighth  annual 
report.  Fifty-five  new  members  were  elected  during  the  past 
year,  and  the  total  number  is  now  441. 

The  Hon.  Curator  reported  that  2,000  slides  had  been  borrowed 
by  members,  and  that  192  preparations  had  been  added  to  the 
collection  during  the  past  twelve  months. 

The   Hon,   Treasurer    presented    the   Annual    Statement    of 


QUEKETT    MICROSCOPICAL    CLUB.  353 

Accounts  and  the  Balance  Sheet  for  1913,  which  had  been  duly 
audited  and  found  correct. 

The  adoption  of  the  Committee's  report  and  the  Balance  Sheet 
was  moved  by  Mr.  A.  M  or  ley  Jones  and  seconded  by  Mr. 
Morland  and  carried  unanimously. 

Mr.  D.  J.  Scourfield,  F.Z.S.,  F.R.M.S.,  Vice-President,  having 
taken  the  chair,  the  annual  address  was  delivered  by  the  President, 
who  took  as  his  subject  "  Organisms  and  Origins." 

The  usual  votes  of  thanks  to  the  President  for  his  address,  and 
to  the  officers  of  the  Club  for  their  services  during  the  past  year, 
were  carried  by  the  meeting.  A  special  vote  of  thanks  was 
passed  to  the  Hon.  Secretary  and  to  Mr.  J.  Grundy  for  their 
services  in  so  successfully  organising  the  recent  conversazione. 


354 


FORTY-EIGHTH   ANNUAL   REPORT. 

Your  Committee  are  glad  to  be  able  to  assure  the  Club  of  its 
continued  prosperity.  During  the  year  ending  December  31st, 
1913,  fifty-five  new  members  were  elected  ;  this  number  has  been 
equalled  only  once,  and  exceeded  only  once — when  there  were 
fifty-seven  elected— during  the  recent  years  of  which  any  record 
has  been  found.  Eleven  have  resigned,  and  four  were  lost  by 
death,  leaving  the  present  number  441.  Among  those  lost  by 
death  should  be  mentioned  the  Eight  Hon.  Sir  Ford  North,  for 
some  years  a  Vice-President  and  a  valued  member  of  the  Club. 
An  obituary  notice  appeared  in  the  November  number  of  the 
Journal. 

Both  the  Ordinary  and  Gossip  Meetings  have  been  well  attended, 
in  fact  on  several  occasions  the  number  present  was  somewhat 
more  than  the  capacity  of  the  room  would  accommodate  with 
a  due  regard  to  comfort. 

The  papers  and  notes  read  and  exhibits  contributed  during  the 
year  were  as  follows  : 

Jan.  W.  M.  Bale,  F.B.M.S.,  of  Victoria,  Australia.     Notes 

on  some  of  the  Discoid  Diatoms.     Communicated  by 
the  President. 
H.    Whitehead,    B.Sc.      British    Freshwater    Bhabdo- 

coelida  (Planarians).     Communicated  by  J.  Wilson. 
C.    F.    Bousselet,    F.B.M.S.      The    Botifera   of    Devil's 

Lake :  Description  of  a  New  Brachionus. 
E.   M.   Nelson,   F.B.M.S.     Note  on  Pleurosigma  angu- 
latum ;     Note    on    a    Coloured    Coma    observed    in 
examining  A.  Ralfsii. 
Feb.  Prof.  A.  Dendy,  D.Sc,  F.B.S.     By-products  of  Organic 

Evolution.     Presidential  Address. 
March.     E.     Heron-Allen,     F.Z.S.,    F.L.S.,    and     A.    Earland, 
F.B.M.S.     On  some  Foraminifera  from  the  Southern 
Area    of    the  North  Sea,   dredged    by  the   Fisheries 
cruiser  Huxley. 
n        D.  Bryce.     Five  New  Species  of  Bdelloid  Botifers. 


j? 


>> 


55 


FORTY-EIGHTH    ANNUAL    RETORT.  355 

April       0.   D.    Soar,    F.L.S.,    F.R.M.S.      Two   New    Species   of 
Water-mites. 
,,  G.  T.  Harris.     The  Collection  and  Preservation  of  the 

Hydroida. 
May.        T.  A.   O'Donohoe       The  Minute  Structure  of  Coscino- 
discics  asteromphalus  and  of  two  Species  of  Pleuro- 
sigraa. 
June.       H.    Sidebottoin.       The    Lagenae    of     the    South-West 
Pacific. 
E.  M.  Nelson,  F.R.M.S.     On  a  New  Method  of  Mea- 
suring the  Magnifying  Power  of  an  Objective. 
Oct.  James  Murray,  F.R.S.E.     The  Gastrotricha. 

,,  E.  M.  Nelson,  F.R.M.S.     Note  on  an  Improved  Form  of 

Apertometer. 
Nov.         James  Burton.     On   the  Disc- like  Termination  of  the 
Flagellum  in  some  Euglenae. 
James    Burton.     On   a   Method    of    Marking   a  Given 

Object  on  a  Mounted  Slide  for  Future  Reference. 
E.  M.  Nelson,  F.R.MS,     On  the  Measurement  of  the 
Initial  Magnification  of  Objectives. 
Dec.  B.  M.  Draper.     On  Dark-ground  Illumination  with  the 

Greenhousdi  Binocular. 


>) 


n 


D 


At  the  Ordinary  Meetings  the  following  slides  and  apparatus 
were  exhibited  : 

Jan.         W.  Watson  Baker.     New  Model  Microscope,  having  a 
Side  screw    Fine   Adjustment,    and    New    Objective 
Changer,  etc. 
„  A.  A.  C.  Eliot  Merlin,  F.R.M.S.     Photomicrographs  of 

Coscinodiscus  heliozoides,  showing  Pseudopodia. 

March.  A.  A.  C.  Eliot  Merlin,  F.R.M.S.  Five  Photomicro- 
graphs taken  at  x  320  of  various  Diatoms. 

April.  Presented  by  G.  T.  Harris.  Mounted  Hydrozoa,  ex- 
hibited under  Microscopes  by  Messrs.  H.  F.  Angus 
&Co. 

May.        J.  Watson,  a  visitor.     A  Slide  showing  Multiple  Images 
formed  by  the  Cornea  of  the  Eye  of  a  Bee. 
E.  Pitt.     Various  Microtomes  exhibited  and  explained, 


3> 


with  Demonstration  of  Ribbon  Section-cutting 


»■ 


Journ.  Q.  M.  C,  Series  II.— No.  74.  25 


») 


" 


o56  FORTY-EIGHTH  ANNUAL  REPORT. 

June.       A.   A.  0.  Eliot  Merlin,  F.R.M.S.      Photomicrograph   of 
Foot  of  Ceylon  Spider. 
E.  M.  Nelson,  F.R.M.S.     A  Slide  of  Green  Trap  show- 
ing Structure  resembling  Vegetable  Tissue. 
,,  W.    Traviss.     Apparatus    for    Use    in    Pond    Hunting, 

enabling  a  Sample  of  Water  to  be  obtained  at  any 
desired  Depth. 
,,  James  Grundy.     Apparatus  for  use  in  connection  with 

E.  M.  Nelson's  paper   "  On   a  Method  of  Measuring 
the  Magnifying  Power  of  an  Objective." 
Oct.  S.  C.  Akehurst.     A  Changer  for  Sub-stage  Condensers. 

S.    C.    Akehurst.       Trap    for    Minute    Free-swimming 

Organisms. 
Messrs.  Grundy,  Cheshire  and  Ainslie.     Various  Aper- 
tometers. 
Nov.         C.  E.  Heath,  F.R.M.S.     Objective  Guard  for  Preventing 

Damage  to  High-power  Objectives. 
Dec.         B.   M.  Draper.     A   New   Form   of  Transparent  "  Live 
Box  "  for  the  Exhibition  of  Living  Organisms,  chiefly 
Insects.     Also    a  Special   Form    of   Stop    for    Dark- 
grouncl  Illumination  with  a  Greenhough  Binocular. 
„  W.  Traviss.     Specimens  of  Quartz  showing  under  the 

Microscope  a  Laminated  Structure. 

Your  Committee  feel  that  the  Club  is  greatly  to  be  congratu- 
lated on  the  inclusion  in  its  Journal  of  such  valuable  papers. 
Not  only  is  their  publication  in  our  Proceedings  an  honour  to  the 
Club,  but  the  actual  value  of  the  communications  as  a  contribu- 
tion to  science,  and  especially  to  that  always  difficult  and  often 
little-appreciated  subject,  classification,  makes  the  Journal  a 
standard  work  of  reference.  The  Club  has  also  been  the  means 
of  making  known  and  recording  a  number  of  new  species  among 
the  Rotifera,  the  Entomostraca,  and  Water-mites,  by  members 
who  are  authorities  in  these  several  classes.  While  thanking 
those  members  who  have  contributed  to  the  success  of  the  Club, 
the  Committee  would  take  this  opportunity  of  urging  upon 
others  the  great  advantage  of  bringing  before  the  Club  subjects  of 
interest  in  the  form  of  short  papers  or  notes,  and  the  profit  they 
would  themselves  obtain  by  putting  their  knowledge  into  the 
concrete    and    definite   shape    required    for   this   purpose.       The 


FORTY-EIGHTH    ANNUAL    REPORT.  357 

Committee  at  the  same  time  wish  it  to  be  remembered  that  one 
of  the  foremost  aims  of  the  Club  is  to  assist  the  amateur  and  the 
beginner,  both  by  providing  papers  of  a  somewhat  elementary 
character,  and  by  assuring  them  that,  particular]}'  at  the  Gossip 
Meetings,  they  will  find  friends  willing  and  anxious  to  assist  them 
in  their  efforts  in  gaining  experience  in  the  best  methods  of  using 
their  instruments,  and  in  the  task  of  identifying  specimens. 

The  Librarian  reports  that  there  has  been  a  fair  demand  for 
books  during  the  year,  but  somewhat  less  than  that  for  1912. 
The  card  index  and  the  numbering  and  rearrangement  of  the 
books  are  nearly  completed,  and  the  path  cleared  for  commencing 
the  final  details  of  the  new  edition  of  the  Catalogue.  The 
thanks  of  the  Club  are  due  to  Messrs.  Caffyn,  Todd  and  L.  C. 
Bennett  for  the  great  amount  of  assistance  they  have  given  the 
Librarian  in  these  matters. 

During  the  year  under   review   the    following   volumes  have 
been  added  : 

LIST  OF  BOOKS  PURCHASED  SINCE  JANUARY  1913. 

British  Parasitic  Copepoda.     T.  &  A.  Scott.     Vols    I.  and  II. 
Ray  Society. 

Bibliography  of    the  Tunicata,   1469 — 1910.      J.   Hopkinson. 
Ray  Society. 

Schmidt's  Atlas  der  Diatomaceen-kunde.     4  Vols. 

Light.     (For  Students  )     Edwin  Edser. 

British  Rust  Fungi.     N.  B.  Grove. 

LIST  OF  BOOKS   PRESENTED   SINCE  JANUARY  1913. 

Presented  by  the  Author,  Dr.  Eugene  Penard  : 

Nouvelles  recherches  sur  les  Amebes  du  Groupe 
Terricola. 

Presented  by  the  Publisher,  John  Murray  : 
Problems  of  Life  and  Reproduction  .         .     Marcus  Hartog. 

Presented  by  J.  Burton  : 
Das  Phytoplankton  pes  Susswassers. 


358  FORTY-EIGHTH    ANNUAL    REPORT. 

Presented  by  the  Author,  Henry  Whitehead. 
British  Freshwater  Leeches. 

Presented  by  Prof.  Arthur  Dendy  : 
Classification  and  Phylogeny  of  the  Calcareous 

Sponges         .         .         .     Arthur  Dendy,  D.Sc.,  F.R.S.,  and 

R.  W.  Harold  Row,  B.Sc. 

With  a  reference  list  of  all  the  described  species  systematically 
arranged. 

Presented  by  the  Author,  Charles  Janet,  Limoges  : 
Le  Volyox  and  Other  Papers. 

Presented  by  the  Authors,  E.  Heron-Allen  and  A.  Earland. 
Clare  Island  Survey  :    Royal  Irish  Academy. 
Part  64,  Foraminifera. 

Presented  by  the  Author,  J.  W.  Gordon  : 
Diffraction  Images. 

Daring    the    year   ending    December    1913    the    Library    has 
received  the  following  publications  : 

Quarterly  Journal  of  Microscojncal  Science. 

Victorian  Naturalist. 

Mikrokosmos. 

Royal  Microscopical  Society. 

British  Association. 

Royal  Institution. 

Geologists'  Association. 

Manchester  Literary  and  Philosophical  Society. 

Hertfordshire  Natural  History  Society. 

Birmingham  Natural  History  and  Philosophical  Society. 

Botanical  Society  of  Edinburgh. 

Glasgow  Naturalists'  Society. 

Croydon  Natural  History  Society. 

Indian  Museum  (Calcutta). 

Royal  Society  of  New  South  Wales. 

American  Microscopical  Society. 

Smithsonian  Institution. 

Academy  of  Natural  Science,  Philadelphia, 


FORTY-EIGHTH    ANNUAL    REPORT.  359 

Missouri  Botanic  Garden. 
Philippine  Journal  of  Science. 
Bergen  Museum. 
Lloyd  Library,  Cincinnati. 
United  States  National  Herbarium. 
Royal  Society.     Series  B. 
Natural  History  Society  of  Glasgow. 
Zoologisch-botanischen  Gesellschaft,  Wien. 
Redia. 

United  States  National  Museum. 
Nuova  Notarisia. 
Nyt  Magazine. 

Liverpool  Microscopical  Society. 
Nova  Scotian  Institute  of  Sciences. 
Royal  Dublin  Society. 
University  of  California. 

Illinois  State  Laboratory  of  Natural  History. 
Societe  Royale  de  Botanique  de  Belgique. 
Brighton  and  Hove  Natural  History  and  Philosophical 

Society. 
Essex  Naturalist. 
Edinburgh  Royal  Botanic  Garden. 

Northumberland  and  Durham  Natural  History  Society. 
Torquay  Natural  History  Society. 

There  were  twelve  Excursions  during  the  year,  which  were  well 
attended,  the  average  number  present  being  20'8.  That  to  the 
Botanic  Gardens  had  the  most  numerous  visitors,  namely  35, 
and  second  to  that  the  grounds  of  Syon  House,  Isle  worth,  with 
33.  Though  no  new  species  appear  to  have  been  recorded  at  the 
outings,  abundant  and  interesting  material  was  acquired,  and  as 
always  the  Excursions  were  marked  by  a  spirit  of  comradeship 
and  social  friendliness,  as  well  as  being  an  opportunity  for 
scientific  acquisition.  It  may  perhaps  be  pointed  out  that  scarcely 
as  much  use  is  made  of  the  results  of  the  excursions  on  the 
subsequent  Gossip  Meetings  as  is  desirable.  Our  thanks  are  due 
to  the  officers  of  the  Botanic  Gardens,  the  East  London  Water 
Works,  and  the  Surrey  Commercial  Docks,  for  their  kindness  in 
allowing  the  Club  to  visit  their  enclosures  for  collecting,  and 
to   the   Duke  of  Northumberland    for   permitting,  through   the 


360  FORTY-EIGHTH    ANNUAL    REPORT. 

kind  intervention  of  his  agent,  the  successful  visit  to  the  grounds 
of  Syon  House.  The  objects  exhibited  at  the  Gossip  Meetings 
have  been  interesting  and  sometimes  noteworthy,  but  it  may  be 
well  to  impress  upon  new  members,  and  beginners  especially,  that 
all  should  make  an  effort  to  bring  a  microscope  and  some  object 
for  display  on  these  occasions.  Not  only  is  this  a  duty  owed 
to  their  fellows,  but  a  distinct  advantage  to  themselves;  they 
thus  become  expert  in  the  use  of  their  instruments  and  in  the 
arrangement  of  their  specimens. 

The  work  of  the  Curator,  carried  on  for  so  many  years,  recently 
under  great  difficulty  owing  to  ill  health,  and  to  the  insufficient 
space  at  his  command,  is  beyond  all  praise,  and  the  best  thanks  of 
the  Club  are  hereby  tendered  to  him  for  his  self-denying  labours. 
The  Curator  reports  that  all  slides  and  apparatus  in  his  charge 
are  in  good  condition,  and  during  the  past  year  a  great  deal  of 
time  has  been  spent  in  revision  and  amalgamation  of  the  collec- 
tions. There  has  been  a  considerable  increase  in  the  number 
of  preparations  borrowed,  upwards  of  2,000  having  gone  out,  and 
even  then  the  number  has  been  unavoidably  restricted  owing 
to  cramped  storage  accommodation.  192  slides  have  been  added, 
72  of  them  by  purchase.  The  beautiful  physiological  prepara- 
tions, accompanied  by  descriptive  letterpress  and  illustrations, 
issued  by  Dr.  Sigmund,  of  wThich  six  series  have  been  added, 
have  been  in  great  request.  A  gap  has  been  filled  by  the 
presentation  of  a  series  of  slides,  with  illustrated  description,  by 
Mr.  Whitehead,  of  Turbellarian  Worms,  a  group  previously  un- 
represented in  the  cabinets.  A  type  collection  of  Hydrozoa, 
presented  by  Mr.  Harris,  has  been  put  to  practical  use,  and,  now 
that  his  accompanying  paper  has  been  printed  in  the  Journal,  is 
likely  to  be  still  further  in  demand.  It  is  hoped  by  the  issue  of 
additional  descriptive  sets  to  still  further  increase  the  usefulness  of 
the  cabinets  from  an  educational  point  of  view.  With  the  kind 
co-operation  of  Mr.  Vogeler  the  Curator  has  been  able  to  issue  a 
supplementary  list  of  part  of  the  botanical  preparations  added 
since  the  general  catalogue  was  printed.  The  hearty  thanks  of 
the  Club  are  due  to  Mr.  Vogeler  for  his  kind  services  in  printing, 
also  to  Mr.  Bestow  for  general  assistance  rendered  the  Curator, 
and  to  the  various  donors  of  slides.  The  Committee  desires  to 
thank  the  officers  generally  for  the  interest  they  have  evinced, 
and  the  often  hard  work  they  have  undertaken  in  carrying  on  the 


FORTY-EIGHTH    ANNUAL    fcEPOfct.  361 

business  of  the  Club  so  successfully.  The  thanks  of  the  Club  are 
due  to  the  editors  of  The  English  Mechanic  and  of  Knowledge 
for  the  reports  of  the  proceedings  published  in  their  papers. 

Finally  the  Committee  feel  that  the  Club  may  look  forward 
with  all  confidence  to  the  future.  Enthusiasm  and  work  are 
the  means  for  continuing  and  increasing  the  success  that  has 
attended  it  from  its  commencement,  and  also  the  means  of 
enabling  us  next  year  to  celebrate  the  Jubilee  of  its  foundation 
in  1865,  by  men  some  of  whom  happily  are  still  with  us  to 
note  with  pride  the  growth  and  vitality  shown  by  the  Club 
they  inaugurated  almost  half  a  century  ago. 


362 


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A   NEW   OBJECT   GLASS   BY   ZEISS,   AND   A   NEW 
METHOD   OF   ILLUMINATION. 

By  Edward  M.  Nelson,  F.R.M.S. 
{Read  March  24///,  1914.) 

Figs.  1-3. 

As  Object  Glass  upon  an  entirely  new  plan  has  been  brought 
out  by  the  firm  of  Carl  Zeiss.  This  lens  has  not  yet  been 
catalogued,  but  as  it  will  undoubtedly  effect  a  considerable 
change  in  the  construction  and  use  of  microscope  objectives  a 
short  account  of  it  may  prove  of  interest  to  the  Club. 

The  object  glass  is  a  short  tube  oil- immersion  1  of  "9  1ST. A. 
Upon  taking  it  out  of  its  black  box  the  first  thing  that  will  be 
noticed  is  that  it  is  nickeled  all  over,  and  the  next  is  that  the 
front  lens  is  set  in  a  push  tube,  and  not  screwed  up  as  usual  ; 
these  two  new  departures  from  the  usual  type  are  also  found  in 
the  oil-immersion  TVth  recently  issued  by  this  firm. 

In  very  early  times  objectives  were  made  on  this  plan.  Both 
Ross  and  Smith,  before  1840,  used  to  screw  the  front  lens  to  a 
tube,  which  was  pushed  on  to  another  holding  the  back  lenses ; 
this  tube  was  then  rotated  until  the  best  point  was  found,  when 
a  small  screw  was  put  in  at  the  side  to  keep  the  tube  in  that 
position. 

This  form  of  construction  has  gone  on  continuously  to  the 
present  day,  especially  in  the  cheaper  series  of  objectives,  while 
the  more  expensive  ones,  including  oil-immersions,  have  had  the 
cells  holding  the  lenses  screwed  into  their  proper  positions.  But 
this  type  of  objective,  so  far  as  I  am  aware,  for  an  oil-immersion 
is  quite  new,  as  also  is  an  oil-immersion  with  a  N.A.  of  less  than 
1'0.  Now  with  regard  to  the  performance  of  this  lens,  the 
corrections  are  very  perfect ;  although  no  fluorite  is  used  in  its 
construction  it  is  very  nearly  apochromatic,  and  shows  a  consider- 
able advance  over  semi-apochromatism,  for  only  a  slight  trace  of 
outstanding  blue  can  be  seen. 

The  defining  power  of  this  objective  is  quite  remarkable,  for  it 
surpasses  all  object  glasses  of  similar  aperture  I  have  seen. 

On  a  M  oiler's  Probe-platte  of  60  diatoms  all  are  resolved  except 

Journ.  Q.  M.  C,  Series  II.— No.  75.  26 


364  E.    M.    NELSON    ON    A    NEW    OBJECT   GLASS    BY    ZEISS, 

the  two  specimens  of  Amphipleura  pellacida.  The  next  most 
difficult  diatom  to  the  Amphipleura  is  the  Nitzschia  curvula,  and 
as  this  diatom  counts  89  thousand  per  inch  it  shows  what  this  new 
lens  can  do  with  oblique  light  and  a  stop,  the  illuminant  being 
an  ordinary  microscope  paraffin  lamp  with  a  \  in.  wick.  With 
axial  light,  without  any  stop,  the  Brazilian  Lindheimeri  is  dotted. 
On  M oiler's  Typen-platte,  with  400  forms,  the  Nitzschia  curvula 
(there  called  the  JV.  sigmatella)  is  very  thin  and  difficult,  and  the 
lens  fails  to  resolve  it,  but  it  easily  resolves  all  the  others  on  that 
line  except  the  Homoeocladia  Martiniana,  which  is  more  difficult 
than  A.  pellucida.  It  resolves  the  N.  crassinervis  on  that  plate 
quite  easily,  and  it  will  just  show  the  striae  on  the  Grammatophora 
oceanica,  which  counts  88  thousand  to  the  inch.  This  diatom  is 
probably  the  G.  subtilissima ;  anyhow,  it  is  very  much  finer  than 
the  diatom  of  the  same  name  on  the  Probe-platte. 

The  image  given  by  this  new  lens  of  the  Poclura  scale  is  very 
fine  indeed.  Undoubtedly  in  this  new  objective  we  have  a  lens 
of  great  beauty  and  power.  An  important  question  arises  as  to 
the  influence  this  lens  will  have  upon  our  battery  of  objectives. 

In  former  times  a  2  in.,  1  in.,  a  |  in.,  a  |  in.  and  ^  in.  or 
yg-  in.  represented  a  full  battery,  but  now  we  may  have  a 
battery  consisting  of  only  a  |  in.  and  an  oil-immersion  TV  in. 
Here  the  gap  is  very  wide,  and  the  new  lens  will  fill  it  very 
satisfactorily. 

This  lens  will,  to  a  certain  extent,  supersede  the  oil-immersion 
TV  in.  in  medical  schools  and  colleges.  It  is  sufficiently  powerful 
to  do  all  that  is  wanted  in  practical  study,  but  necessarily  in 
research  work  a  TV  in.  of  wider  aperture  is  required.  For  a 
student  it  will  be  especially  valuable,  for  it  has  of  course  more 
working  distance  and  a  larger  field  than  a  TV  in. 

Another  very  important  point  is  that,  because  of  its  great 
working  distance,  it  does  not  pick  up  by  capillary  attraction  an 
unfixed  cover-glass.  This  is  a  source  of  great  trouble  when 
working  with  a  -—  in. 

Zeiss  supply  a  funnel  for  reducing  the  aperture  of  this  objec- 
tive, so  that  a  dark  ground  may  be  obtained  with  an  ordinary 
dry  condenser  and  a  stop.  Of  course  with  an  oil-immersion 
condenser  no  funnel  is  required. 

Henceforth,  for  research  work,  a  perfect  battery  will  consist  of 
a  2  in.,  1  in.,  |  in.,  ^  in.,  this  iin.,  and  a  TV  in.  oil-immersion. 


AND    A    NEW    METHOD    OF    ILLUMINATION.  365 

In  the  Navy,  when  Dreadnoughts  were  introduced,  old-fashioned 
battleships  were  scrapped  ;  so  also  in  microscopical  affairs  those 
who  are  wise  will  scrap  all  their  dry  lenses  of  powers  higher  than 
3  in.  or  ^  in. 

One  can  foresee  that  the  advent  of  this  new  lens  means  much, 
for  just  as  oil-immersions  have  eclipsed  water-immersions,  so  will 
this  new  lens  supersede  the  wide-angled  dry  lens,  which  cannot 
compete  with  it  in  working  distance,  quality,  field,  or  price. 

It  is  to  be  hoped  that  Zeiss  will  issue  an  objective  of  this  class 
for  the  long  as  well  as  for  the  short  tube.  The  most  notable 
feature  in  this  new  object  glass  is  the  near  approach  that  has 
been  made  towards  apochromatism  without  the  use  of  fluorspar. 

There  is,  however,  another  matter  for  your  notice — viz.  an 
entirely  new  way  of  using   an  object  glass  for  diatom  or  other 


a 


Fig.  1. 

resolutions,  a  method,  moreover,  for  which  this  new  object  glass 
is  peculiarly  suited.  The  method  is  so  simple  that  it  can  be 
explained  in  a  few  words  :  (1)  Place  the  diatom  so  that  the  striae 
to  be  resolved  are  vertical  in  the  field.  (2)  Set  up  a  critical 
imawe  with  the  edge  of  the  flame  in  focus  and  central  to  the 
field,  and  open  the  diaphragm  to  its  full  extent.  (3)  By  means 
of  the  substage  centring  screws  move  the  condenser  so  that  the 
image  of  the  flame  lies  just  outside  the  field  of  a  high-power 
eye- piece  (fig.  1).  If  the  striae  are  within  the  grip  of  the  object 
glass  they  will  be  resolved. 

It  just  amounts  to  this,  that  if  one  is  working  at  diatoms 
with  critical  illumination  and  has  need  to  resolve  one,  all  that  is 
necessary  is  to  move  the  side  way  adjusting  screw  of  the  substage 
and  place  the  flame  image  just  outside  the  field,  and  the  thing  is 
done  in  an  instant,  without  any  trouble  with  stops,  slots,  or 
other  apparatus. 

You  will  notice  that  the  amount  of  the  displacement  of  the 
condenser  is  very  small  (say  twice  the  length  of  a  Kavicida  rhom- 


366  E.    M.    NELSON    ON    A    NEW    OBJECT    GLASS    BY    ZEISS. 

boides),  so  that  this  new  kind  of  illumination  must  not  be 
confused  with  that  from  a  condenser  considerably  decentred, 
with  the  illuminant  so  placed  that  the  light  passes  through  the 
condenser  obliquely,  a  form  of  illumination  old  and  well  known, 
or  rather  which  used  to  be  well  known. 

Although  there  is  no  difficulty  in  executing  the  necessary 
manipulation,  the  explanation  of  how  the  result  is  obtained  is  not 
so  easy.  First,  no  direct  light  from  the  flame  enters  the  field,  but 
it  must  be  remembered  that  it  is  not  a  dark-ground  image  we  are 
dealing  with ;  for  if  it  were  high  resolution  would  fail,  as  Mr. 
W.  B.  Stokes  has  pointed  out.  The  field  is  not  dark,  neither  is  it 
light,  but  it  is  a  sort  of  glow ;  from  whence  does  this  glow  come  ? 
At  first  it  was  thought  that  it  must  arise  from  internal  reflections 
in  the  front  lens  of  the  object  glass,  and  that  the  lens  was  acting 


Fig.  2.  Fig. 


3. 


as  its  own  lieberkiihn,  as  in  fig.  2.  But  further  experiments  have 
proved  that  this  is  not  the  case  ;  no  doubt  some  light  may  travel 
in  that  manner,  but  the  amount  that  does  so  is  quite  small,  and 
wholly  insufficient  for  the  purpose.  The  main  body  of  this  light 
is  present  owing  to  spherical  aberration  in  the  condenser,  which 
gives  rise  to  a  very  oblique  beam,  as  in  fig.  3.  For  this  kind  of 
illumination  therefore  a  condenser  with  spherical  aberration  is  to 
be  preferred  to  one  more  aplanatic. 

There  can  be  no  question  about  extraneous  light  from  the 
illuminant  having  anything  to  do  with  it,  for  when  a  metal 
screen,  with  a  slit  the  size  of  the  edge  of  the  flame,  was  placed 
close  to  the  chimney,  no  difference  in  the  effect  was  observed. 

This  kind  of  illumination  will  be  of  service,  for  it  will  enable  an 
observer  to  obtain  high  resolution  with  a  dry  condenser,  in  an 
instant,  without  the  troublesome  manipulations  usually  necessary. 

Journ.  Quekett  Microscopical  Club,  8a:  2,  Vol.  XII.,  No.  7"»,  November  1914. 


307 


A     NEW     LOW-POWER     CONDENSER. 

By  Edward  M.  Nelson,  FJR.M.S. 
{Read  April  28a,  1914). 

Fig.  4. 

Some  time  ago  1  pointed  out  to  the  Club  that  microscopists  were 
badly  off  for  a  low-power  condenser,  for,  so  far  as  I  know,  there 
is  no  such  appliance  to  be  had.  Mr.  Curties  kindly  exhibits- 
to-night  one  he  has  made  from  my  formula.  This  condenser  is 
designed  as  a  low-power  illuminator,  and  not  at  all  for  the 
purpose  of  resolving  fine  diatom  striae.  With  the  top  on,  its 
focus  is  1  inch,  and  with  the  top  off  2  inches.*  Both  the  lenses 
are  achromatised,  and  it  will  be  seen  that  it  is  particularly 
achromatic,  as  well  as  aplanatic ;  it  will  work  from  the  lowest 
powers  up  to  a  |  inch. 

The  first  object  I  examined  with  it  was  a  Navicula  lyra,  with 
a  Zeiss  12  mm.  apochromat.  I  have  been  working  with  the 
microscope  now  upwards  of  forty  years,  and  never  before  have  I 
seen  such  a  perfect  image  of  this  diatom.  In  general  work, 
with  the  lower  powers,  the  flat  of  the  flame  of  a  reading 
lamp  is  focused  upon  the  object ;  this  with  the  2  inch  condenser 
covers  a  large  portion  of  the  field,  even  of  the  lowest  powers.  It 
will  give  an  excellent  dark-ground  for  pond  life,  etc.,  up  to  say  a 
|  inch  objective.  This  condenser  is  to  be  named  "  Quekett," 
after  that  illustrious  microscopist. 

Speaking  of  dark  backgrounds,  there  is  a  great  defect  in  many 
condensers,  viz.  that  the  spot  is  not  centred  to  the  optic  axis  of 
the  condenser,  because  the  cell  holding  the  stops  is  not  placed 
accurately  on  the  mount.  This  is  a  serious  defect,  because  if  the 
stop  is  not  centred,  the  microscopist  is  forced  to  use  a  much  larger 

*  This  back  lens  of  2-inch  focus  when  used  by  itself  in  a  holder  forms 
the  best  "verant"  I  have  seen.  It  is  very  useful  for  the  examination 
of  large  microscopical  objects,  as  well  as  of  flowers,  engravings,  coin-, 
postage  stamps,  seals,  etc. 


368 


E.    M.    NELSON    ON    A    NEW    LOW-POWER    CONDENSER. 


stop  than  is  necessary.*  How  often  one  sees  a  dimly  lighted 
object,  with  a  halo  of  bright  fog,  on  one  side  of  the  field,  owing 
to  the  use  of  an  excentric  stop  larger  than  is  necessary. 

To  remedy  this  defect,  Mr.  Curties  shows  a  simple  centring 
stop-holder  made  from  my  design.  The  stop  consists  of  a  disc 
with  a  hole  in  it  which  fits  on  a  pin  B ;  this  I  designed  for  my 
Jubilee  microscope,  which  was  made  by  Powell  and  exhibited  at 
the  Club  in  1887. 

Why  microscopists  will  have  their  stops  cut  out  of  the  sheet,  a 
much  more  expensive  plan  than  a  disc  fitting  on  a  pin  on  a  spider, 


ZI 


v 


Fig.  4. 

A,  lever ;  B.  flat  tube  with  the  stop  on  pin  ;  C  shows  the  flat  tube  placed 
on  the  lever,  with  screw  for  fixing  the  appliance  beneath  the  iris-box. 

I  am  unable  to  tell  you.  But  to  return,  this  pin  is  fixed  to  the 
end  of  a  flat  tube  B,  which  slides  on  a  flat  bar  A  ;  this  forms  the 
centring  adjustment  right  and  left.  The  centring  adjustment 
rectangular  to  this  is  in  arc,  by  moving  the  arm  C,  which  is 
pivoted  below  the  iris  box. 

*  If,  for  example,  a  centred  stop  of  -4-inch  diameter  is  requisite,  and 
supposing  that  the  stop  carrier  is  1  inch  out  of  centre,  then  a  stop  of 
•6  inch  will  be  required  to  do  the  same  work  as  the  stop  of  *4  inch.  Now 
the  area  of  a  circle  of  "6  inch  diameter  is  more  than  double  that  of  a  circle 
•4  inch  diameter  ;  this  shows  the  great  loss  of  light  an  excentric  stop-holder 
causes. 


Journ.  Quek-ett  Microscopical  Club,  Scr.  2,  Vol.  XII. ,  No.  75,  November  1914. 


369 


BINOCULAR    MICROSCOPES. 

By  Edward  M.  Nelson,  F.R.M.S. 
(Bead.  May  2tth,  1914.) 

Fig.  5. 

In  recent  years  several  binoculars  have  been  introduced  ;  none 
of  them,  however,  can  be  called  new.  The  first,  the  Greenough, 
by  Zeiss  *  in  1897  was  a  twin  microscope,  a  form  of  binocular 
invented  by  Pere  Cherubin  d'Orleans  nearly  three  hundred  years 
ago.  The  second,  by  F.  E.  Ives  in  1902,f  is  very  similar  to  one 
designed  by  Wenham  in  1866  as  a  counterblast  to  Powell's 
high -power  binocular  in  which  the  whole  beam  is  sent  into 
each  eye.  %  The  third  is  a  modification  of  the  second  by  Messrs. 
Leitz,§  and  the  fourth,  by  Messrs.  Beck,  is  very  similar  to  that 
of  Ives. 

Before  proceeding,  let  us  enumerate  the  points  gained  by 
binocular  vision.  They  are  four  in  number  and  were  stated 
by  me  in  the  English  Mechanic  ||  as  follows  : 

1.  Stereoscopism,  or  the  power  of  appreciating  solidity. 

2.  Increase  of  apparent  magnifying  power. 

3.  Increase  of  illumination. 

4.  Increase  of  colour  perception. 

The  first  binocular  we  have  to  deal  with,  viz.  the  Greenough 
twin  microscope,  became  a  practical  form  owing  to  the  re- 
introduction  of  the  Porro  prism  by  C.  D.  Ahrens  in  1888. 
Obviously,  it  can  only  be  used  with  very  low  powers,  but  never- 
theless I  have  had  no  reason  to  alter  the  favourable  opinion 
I  expressed  for  this  form  of  binocular  when  it  was  first  ex- 
hibited  by    Messrs.   Zeiss.     In    this   instrument   all   the   above 

*  Journ.  B.M.S.,  1897,  pp.  599-600. 
t  Ibid.,  1903,  p.  85,  Fig.  3. 

X  I  am  indebted  to  Mr.  Rousselet  for  kindly  bringing  the  Ives  binocular 
to  my  notice. 

§  Journ.  B.M.S.,  1914,  p.  5. 
||  1911,  Vol.  94,  No.  2432. 


370  E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES. 

four  attributes  of  binocular  vision  are  secured.  In  tins  micro- 
scops  the  left-hand  view  of  the  objective  is  sent  into  the  left 
eye,  and  the  right-hand  view  into  the  right  eye;  this,  because 
of  the  erection  of  the  image,  gives  an  ortho-stereoscopic  image. 
If  the  microscope  had  been  of  the  ordinary  inverting  type  the 
image  would  have  been  pseudo-stereoscopic.  It  was  due  to 
ignorance  of  this  principle  that  several  of  the  early  bino- 
culars were  pseudo-stereoscopes.  One  of  the  most  important 
points  in  this,  as  well  as  in  all  forms  of  binoculars,  is  that 
the  images  should  be  accurately  superimposed.  Several  tests 
have  been  proposed ;  one  was  that  an  object  should  be 
placed  upon  the  stage,  so  that  it  should  just  touch,  say,  the 
right  edge  of  the  field  of  the  right-hand  eye-piece.  This  eye- 
piece is  then  transferred  to  the  left-hand  tube,  and  if  the  object 
still  touches  the  same  portion  of  the  field  with  the  same  eye- 
piece the  adjustment  was  supposed  to  be  correct.  But  this 
is  no  test  at  all,  for  it  tells  you  nothing  about  the  really 
important  question,  which  is  whether  the  discs  of  the  fields 
are  themselves  superimposed. 

The  best  test  for  a  Greenough  is  to  oscillate  rapidly  a  strip 
of  card  half-inch  wide  before  the  fronts  of  the  objectives.  If 
the  images  shake,  then  they  are  not  accurately  superimposed, 
and  the  objectives  require  readjusting  in  their  seats. 

Leaving  now  the  twin  microscope,  we  will  pass  on  to  the 
other  kind  of  binocular,  which  has  only  one  objective.  In  the 
Wenham  this  important  adjustment  is  performed  by  the  align- 
ment of  the  tubes,  for  the  tilt  of  the  prism  has  very  little 
effect,  but  its  edge  must  be  carefully  set  at  right  angles  to 
a  line  joining  the  centres  of  the  eye-pieces. 

The  single  objective  binocular  may  be  divided  into  two  kinds, 
viz.  those  of  the  Wenham  or  Stephenson  type,  which  split  the 
beam  at  the  back  of  the  objective,  and  those  of  the  Fowell  type, 
which  pass  the  whole  beam.  All  those  of  the  Wenham  type 
possess  the  first  of  the  attributes  enumerated  above,  viz.  stereo- 
scopic effect,  for  in  an  ordinary  inverting  microscope,  at  the 
left-hand  eye-piece  the  Ramsden  disc  will  be  a  miniature  of 
a  cross-section  of  the  beam  issuing  from  the  right-hand  half 
of  the  objective,  and  that  at  the  right-hand  eye-piece  from  the 
left-hand  half  of  the  objective,  the  inversion  of  the  image 
necessitating  a  cross-over  of   the  pencils,  for   if   there  were  no 


E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES.  371 

cross-over  the  image  would  be  pseudo- stereoscopic.  There  is 
no  cross-over  in  a  Stephenson,  but  then  it  is  an  erecting 
microscope. 

The  binocular  of  the  Powell  type,  which  passes  the  whole 
pencil,  does  not  possess  the  first  attribute  of  stereoscopism  :  the 
image  in  both  eyes  being  identically  the  same.  No  doubt, 
owing  to  the  employment  of  both  eyes  and  for  physiological 
reasons,  there  may  be  more  or  less  of  a  stereoscopic  effect,  but 
that  is  an  entirely  different  thing  from  true  stereoscopism. 
When,  for  example,  the  full  moon  is  observed  through  a  field- 
glass  it  appears  as  spherical  as  a  cricket-ball,  the  images  in 
each  eye  must  be  identical  and  no  true  stereoscopism  can  be 
present. 

If  half  the  Kamsden's  disc  above  the  eye-lens  is  stopped  out 
by  a  diaphragm,  so  long  as  the  cross-over  is  preserved,  the 
image  in  an  inverting  microscope  will  be  ortho-stereoscopic.  This 
was  mentioned  by  "Wenham  in  1854;  and  later,  in  1882,  Dr. 
Mercer  pointed  out  that  a  diaphragm  is  not  needed,  but  an 
ortho-stereoscopic  effect  may  be  obtained  by  making  the  inter- 
ocular  distance  less  than  the  interpupillary,  which  causes  the 
iris  of  the  pupil  of  the  eye  to  cut  off  the  inner  half  of  the 
Ramsden  disc. 

The  disadvantage  of  a  diaphragm  above  the  eye-piece  is  that 
it  occupies  the  same  place  as  that  in  which  the  eye  ought  to  be; 
and  the  disadvantage  of  Dr.  Mercer's  method  is  that  the  head 
and  eyes  must  be  kept  absolutely  steady,  otherwise  there  will  be 
a  flickering  of  the  image,  which  causes  strain  and  distress  to 
the  eyes  :  the  higher  the  power,  the  smaller  the  Kamsden  disc 
and  the  greater  will  be  the  flickering  and  strain  and  fatigue 
to  the  eyes.  For  these  causes  ortho-stereoscopism  in  a  binocular 
of  the  Powell  type  is  of  a  different  character  from  that  of  the 
Wenham  or  Stephenson  type.  In  books  dealing  with  this 
subject  the  Wenham  super-eye-piece  diaphragm  and  the  Mercer 
narrow  inter-ocular  distance  are  treated  as  alternative  plans, 
equal  in  efficiency  to  the  Wenham  divided  objective  method. 
Such,  however,  is  not  the  case.  It  is  only  necessary  to  place 
two  microscopes  alongside  each  other,  charged  with  similar 
objectives  and  powers,  one  having  a  Wenham  divided  objective 
and  the  other  a  Mercer  narrowed  inter-ocular  distance,  when 
an  examination  of  the  same  object  will  at  once  dispel  any  theory 


372  E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES. 

as  to  the  equality  of  the  results,  the  ortho-stereoscopism  in 
the  Wenham  being  superior  to  that  in  the  other. 

In  the  Wenham  and  Stephenson,  ortho-stereoscopism  is  weak 
with  objectives  which  have  less  than  20°  of  angular  aperture  (say 
1^  inch  of  *17  N.A.),  and  the  divided  objective  breaks  down  with 
high  powers.  A  divided  objective  binocular  may  be  said  to  be  at 
its  best  with  a  \  inch ;  good  with  1  inch,  |,  T4(j-,  and  g ;  fair  with  \  ; 
but  failing  with  a  4.  Very  small  Wenham  prisms  have  been 
made  and  mounted  on  a  funnel  and  placed  in  the  mounts  of  a 
Y2- ',  the  result  being  so  indifferent  that  further  experiments 
in  that  direction  were  abandoned. 

The  Wenham  plan  possesses  a  great  advantage  over  all  other 
kinds  of  stereoscopic  binoculars,  viz.  that  the  straight  tube  is 
free  from  glasses,  prisms,  or  other  appliances  likely  to  disturb  the 
image.  You  will  naturally  ask,  Why  then  was -the  Powell  non- 
stereoscopic  system  introduced  ?  The  answer  is  that  it  was 
intended  to  come  in  where  the  W'enham  left  off,  for  Powell 
engraved  on  his  Wenham  prism,  "  For  Low  Powers,"  and  on  his 
own  prism,  "  For  High  Powers."  The  reason  why  the  high-power 
prism  fell  into  disuse  was  on  account  of  the  poor  definition  that 
could  be  obtained  with  it.  It  bad  no  clear  tube  like  the  Wenham, 
and  it  should  be  remembered  that  prisms  and  flat  glass  surfaces, 
owing  to  the  manufacture  of  prism  field-glasses,  are  now  made 
with  a  precision  and  accuracy  altogether  unknown  in  1865,  when 
Powell  made  his. 

Binoculars  of  the  Wenham  or  divided  lens  type  have  the  dis- 
advantage of  indifferent  definition  of  objects  placed  vertically 
in  the  field.  If,  for  example,  that  well-known  test  for  medium 
powers,  the  hair  of  the  Polyxenus  lagurus,  be  placed  vertically  in 
the  Wenham,  with,  say,  a  one-third  objective,  the  definition 
will  be  fuzzy  ;  but  directly  the  hair  is  placed  horizontally  in  the 
field,  the  image  becomes  sharp.  In  ordinary  work  with  a 
Wenham,  where  an  ortho-stereoscopic  image  is  of  primary  im- 
portance, this  defect  is  not  noticed,  and  probably  only  a  few 
raicroscopists  are  acquainted  with  it.  But  with  the  Powell  type 
of  binocular,  this  error  does  not  exist.  The  image  is  the  same 
in  all  azimuths.  Now,  in  the  Wenham  high-power  binocular, 
which  was  introduced  in  reply  to  Powell's,  the  beam  was  divided 
by  two  right-angled  prisms  with  an  air-space  between  tbem,  the 
inclination  of  the  surfaces  being   adjusted  near  to  the  critical 


E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES.  373 

angle  so  that  some  of  the  light  was  passed  while  some  was 
reflected.  As  this  took  place  at  both  surfaces  a  double  image 
was  made  in  one  tube,  which,  of  course,  was  fatal  to  the  design, 
and  the  binocular  never  came  into  use.  Prof.  Abbe's  binocular 
eye-piece  was  made  on  a  similar  plan  and  failed  for  the  same 
reason.  Subsequently,  however,  a  method  was  discovered  for 
depositing  a  semi-translucent  film  of  silver  on  glass,  by  which 
means  a  beam  could  be  half  reflected  and  half  transmitted.  This 
method  was  adopted  by  Ives,  and  the  doubling  of  the  image  in  the 
one  tube  was  avoided.  The  Ives  binocular  resembled  the  Wenham, 
inasmuch  as  the  prism  could  be  withdrawn  and  the  instrument 
used  as  a  monocular.  But  it  also  differed  from  it,  for  in  the 
Wenham  the  inter-ocular  distance  was  adjusted  by  lengthening 
or  shortening  the  draw-tubes,  while  in  the  Ives  it  was  accom- 
plished by  a  lateral  displacement  of  the  side  tube  in  arc,  the 
lower  end  of  this  tube  being  pivoted  on  a  hinge.  This  was 
a  good  design,  for  it  permitted  the  inter-ocular  distance  to  be 
adjusted  without  disturbing  the  tube  length.  In  1860,  when  the 
Wenham  was  first  introduced,  low  powers,  with  their  double 
fronts,  were  very  insensible  to  alteration  of  tube  length,  and  as 
all  powers  higher  than  a  |  had  correction  collars,  any  alteration 
of  tube  length  was  of  no  moment ;  this,  however,  no  longer 
applies,  because  objectives  now  made  with  single  fronts  having 
over-corrected  backs  are  very  sensitive  to  tube  length.  So  in 
designing  a  binocular  for  use  with  such  objectives,  particular 
attention  must  be  given  to  tube-length  adjustment. 

Now,  lately,  Messrs.  Leitz  have  brought  out  a  new  binocular  of 
the  Powell  type ;  the  arrangement  of  the  prisms,  which  deflect  the 
rays  right  and  left,  differs  from  the  many  kinds  that  have  been 
invented  for  this  purpose.  The  semi- translucent  silver  film 
method  has  been  adopted  by  Messrs.  Leitz  in  their  new  binocular, 
and  an  almost  equally  illuminated  image  is  seen  in  each  tube. 
By  means  of  their  very  perfect  system  of  working  prisms  they 
have  secured  a  really  sharp  critical  image  in  each  tube.  The 
tubes  are  parallel  to  one  another,  but  the  instrument  cannot  be 
used  as  a  monocular,  for  neither  body  is  in  the  optic  axis  of  the 
objective.  Messrs.  Beck  have  also  brought  out  a  binocular 
microscope  with  the  two  Ives  prisms  joined  in  one.  The  bodies 
are  converging,  but  as  one  body  is  in  the  optic  axis  of  the 
instrument,  it  can  be  used  as  a  monocular. 


374  E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES. 

A  great  deal  has  been  made  of  the  difference  between  parallel 
and  converging  tubes.  It  has  been  urged  that  parallel  tubes  are 
conducive  of  eye  strain  and  fatigue.  Having  now  had  a  Leitz 
microscope  in  constant  use  for  nearly  three  months,  and  having 
done  prolonged  work  with  it,  no  more  eye-strain  has  been  found 
with  the  parallel  tubes  than  with  a  Wenham,  and  with  both 
there  is  less  fatigue  than  with  a  monocular. 

To  me  the  image  plane  in  a  microscope  appears  at  so  definite 
a  distance  that  I  seem  able  to  hold  a  pencil  in  front  of  it,  or 
behind  it,  or  touching  it.  When  using  a  binocular  I  simply  look 
at  the  image  in  this  plane,  being  quite  as  unconscious  of  either 
the  parallelism  or  convergence  of  the  eyes  as  if  I  were  looking  at 
various  objects  in  the  room,  or  on  the  table.  During  the  course 
of  these  experiments  several  curious  observations  were  made. 
Various  persons  were  asked  to  examine  the  images  in  the  Wenham 
and  in  the  Leitz  for  the  purpose  of  ascertaining  their  opinion  as 


W  M 

Fig.  5, 

to  the  relative  amount  of  stereoscopic  effect  in  each.  Two  persons 
having  good  normal  vision  saw  no  stereoscopic  effect  in  either, 
the  images  in  both  instruments  appearing  quite  flat ;  one  of  them 
could  see  no  stereoscopic  effect  either  in  an  ordinary  stereoscope 
or  in  a  field  glass.  Two  others  saw  stereoscopism  in  the  Wenham, 
but  not  in  the  Leitz  with  the  Mercer  method.  With  the  same 
object  and  same  power  in  both  (|  inch  and  B  eye-piece),  most 
persons  said  that  stereoscopism  was  stronger  in  the  Wenham, 
owing  probably  to  want  of  practice  and  experience  with  the 
Mercer  method. 

When  the  inter-ocular  distance  in  the  new  binocular  is  kept 
of  the  same  width  as  the  inter-pupillary,  the  microscope  is  a 
non-stereoscopic  binocular.  The  Mercer  plan  of  reducing  the 
inter-ocular  distance  is  found  to  produce  fatigue  on  account  of 
the  flickering  of  the  image  when  the  Ramsden  disc  is  small. 

Figure  5  shows  the  reason  why  eye  strain  and  fatigue, 
which   are  present  with    the   Mercer    method,   are   absent   with 


E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES.  375 

the  Wenhani ;   the  circles  in  W  and  M  represent  the  pupil  of 
the  eye,  the  semi-circle  in  W  is  the  Ramsden  disc  in  a  Wenham, 
and  the  portion  of  the  circle  in  M  is  the  Ramsden  disc  when 
the  inter-ocular  distance  is  less  than  the  inter-pupillary  in   the 
Mercer  method.     It  can  at  once  be  seen  that  a  slight  movement 
of  the  head  will  not  affect  the  luminosity  in  W,  but  in  M  the 
head   cannot   be   moved   in   the   slightest   degree   without   either 
increasing   or   diminishing    the    amount    of    the    Ramsden    disc 
cut  off  by  the  iris  of  the  pupil ;  necessarily,  therefore,  if  in  one 
eye  the  Ramsden  disc  is  enlarged  it  is  cut  off  in  the  other  eye, 
and  vice  versa,  which  is  the  cause  of  the  nickering  previously 
mentioned.     A  moment's  consideration  will  show  how  this  defect 
in  the  Mercer  method   may  to  a  certain  extent  be   minimised. 
Obviously  the  larger  the  Ramsden  disc  the  less  noticeable  will  be 
this  defect.     This,  of  course,  points  to  the  use  of  a  low-power 
eye-piece  with  any  given   objective.       The  low-power  eye -piece 
has  an   additional    advantage — -viz.   that   the  rays  emerge   at  a 
smaller  angle  than  in  the   case  of  a  deep   eye-piece,   and  this 
permits  the  eye  being  held  at  a  little  distance  from  the  proper 
eye-point,  where  the  Ramsden   disc  is  expanded.       Hence   the 
rule  for  stereoscopism  with  the  new   binocular  is  to  make   the 
inter-ocular  distance  somewhat  less  than  the  inter-pupillary,  and 
not  to  use  eye-pieces  deeper  than  1|  inches,  and  to  hold  the  eye 
a  little  way  behind  the  eye-point. 

There  are  two  other  sources  of  eye  strain  and  fatigue  common 
to  all  binoculars  of  whatever  type  :  the  first  is  non -coincidence 
of  the  superimposed  fields.  This  by  no  means  uncommon  fault 
is  due  to  carelessness  in  fitting  and  putting  together  ;  it  is  a 
source  of  great  eye  strain  and  fatigue,  and  the  purchaser  of  a 
binocular  microscope  should  be  particular  to  see  that  the  fields 
are  precisely  superimposed.  The  second  is  a  difference  of  foci 
in  the  tubes.  In  the  binoculars  both  of  Messrs.  Leitz  and  Beck 
provision  is  made  for  this  by  a  focusing  arrangement  in  one  of 
the  eye-tubes.  In  the  Greenough  it  is  accomplished  by  means 
of  a  focusing  adjustment  in  one  of  the  objectives.  If,  therefore, 
a  microscope  is  provided  with  some  such  arrangement,  the  user 
need  not  be  troubled  about  this  point. 

Passing  on  now  to  the  second  attribute  of  a  binocular — viz. 
that  of  increased  apparent  magnifying  power,  it  is  found  to  be 
as  obvious  in  a  microscope  as  it  is  in  a  field  glass.     Its  precise 


376  E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES. 

amount  is  difficult  to  determine,  nor  is  it  known  if  it  is  the 
same  for  all  persons.  As  I  pointed  out  elsewhere,  it  is  inaccurate 
to  say  that  there  is  an  increase  of  apparent  magnification  in  a 
binocular ;  what  really  takes  place  is  that  in  a  monocular  there 
is  a  diminution  of  apparent  magnifying  power,  and  that  this  dimi- 
nution is  non-existent  in  a  binocular.  If  any  one  examines  a 
lighthouse,  a  ship,  or  other  object  with  a  2  or  3  power  monocular 
telescope,  the  image  appears  no  larger  than  when  it  is  seen  with 
the  naked  eye.  The  image,  as  any  one  will  tell  you,  is  brighter 
and  clearer,  but  not  larger.  Directly  the  image  seen  in  the 
telescope  is  superimposed  on  that  seen  with  the  other  eye  the 
magnification  of  the  monocular  is  demonstrated,  which  generally 
causes  surprise.  Having  given  this  subject  considerable  attention, 
I  am  of  opinion  that  the  true  magnification  is  seen  in  a  binocular, 
but  that  with  a  monocular,  either  telescope  or  microscope,  this 
is  reduced. 

The  third  attribute — viz.  illumination  :  It  is  doubtful  if  there 
is  much  gain  in  the  Greenough  type  of  binocular,  as  the  amount 
gained  by  the  use  of  both  eyes  is  probably  lost  owing  to 
the  prisms,  surface  reflections,  etc.  Of  course,  with  a  single 
objective  type  of  instrument  there  must  be  a  loss.  This  is  of 
no  importance,  for  in  a  microscope  one  has  usually  more  light 
than  is  needed. 

The  fourth  attribute  :  Experiments  have  shown  that  colour 
tints  are  increased  in  a  binocular  ;  this  is  a  distinct  gain,  for 
there  is  always  much  and  often  total  loss  of  colour  in  micro- 
scopical observations. 

There  is  another  form  of  binocular  which  must  be  mentioned, 
viz.  the  binocular  eye-piece.  This  was  an  early  invention  of 
Wenham ;  the  next  to  take  it  up  was  Tolles,  of  Boston,  U.S.A., 
who  made  a  very  good  one  by  using  prisms  on  the  Nachet 
plan,  dividing  the  beam  by  means  of  an  isosceles  prism.  Tolles' 
binocular  was  well  made,  stood  deep  eye-pieces,  and  had  the 
advantage  that  both  tubes  were  similar  ;  consequently  the  illumi- 
nation and  path  of  the  rays  was  equal  in  each.  The  advantage 
this  system  possesses  is  that  it  permits  of  objective  correction  by 
draw  tube.  With  other  binoculars  objective  correction  is  not  so 
easily  accomplished. 

The  last  form  of  binocular  eye-piece  was  brought  out  by 
Professor  Abbe.     This,  as  we  have  seen  above,  was  a  failure. 


E.    If.    NELSON    ON    BINOCULAR    MICROSCOPES.  377 

There  was  another  objection,  viz.  that  the  path  of  the  rays  was 
much  longer  in  one  tube  than  in  the  other,  so  that  two  different 
forms  of  eye-pieces  had  to  be  used.  Very  few  were  made,  and 
it  is  probable  that  no  more  will  be. 

In  conclusion  let  us  examine  the  position  of  these  new 
binoculars.  From  what  has  been  said  above  they  are  clearly  a 
class  by  themselves.  It  would  be  quite  inaccurate  to  entertain 
the  idea  that  these  instruments  are  a  new  kind  of  stereoscopic 
binocular  constructed  to  enter  into  competition  with,  and  finally 
to  supersede,  the  existing  binoculars  of  the  Wenham  and 
Stephenson  types  ;  for  from  what  we  have  seen  they  only  possess 
the  first  attribute,  viz.  stereoscopism  in  a  limited  manner.  The 
word  "limited"  is  used  in  default  of  a  better  expression.  It 
does  not  mean  that  with  the  Mercer  effect  stereoscopism  becomes 
less  strong,  for,  on  the  contrary,  with  the  Mercer  effect  hyper- 
stereoscopism  is  often  present,  and  care  should  always  be  taken 
to  guard  against  it.  With  the  Mercer  effect  a  cell,  for  example, 
which  is,  and  which  under  a  Wenham  would  look,  like  an 
ellipsoidal  football  will  appear  under  a  hyper-stereoscopic  Mercer 
effect  as  if  standing  on  end. 

The  centre  of  that  beautiful  diatom,  plentiful  on  "  Mud 
Cuxhaven  "  slides,  viz.  Actinocyclus  Ralfsii,  under  hyper-stereo- 
scopism  appears  at  the  bottom  of  a  deep  pit,  the  outer  annulus 
being  highly  raised,*  whereas  we  know  that  the  structure  is  a 
kind  of  shallow  saucer.  The  word  "limited"  is  intended  to 
apply  to  the  stereoscopic  condition  that  the  Itamsden  disc  cannot 
be  centred  to  the  pupil.  The  Mercer  plan  also  entails  loss  of 
light  and  of  resolution  of  vertical  striae.  Messrs.  Leitz  provide 
their  inter-ocular  adjustment  with  a  millimetre  scale.  The 
observer  should  carefully  note  the  precise  adjustment  that  will 
centre  the  Ramsden  disc  to  his  own  eyes  ;  half  a  division  on  the 
scale  (which  represents  1  mm.)  or  even  less  ought  to  suffice  for 
the  Mercer  effect.  The  test  of  coincidence  of  the  inter-ocular 
with  the  inter-pupillary  distance  is  that  of  maximum  brightness. 
Luminosity  quickly  falls  off  with  either  increase  or  decrease  of 
inter-ocular  distance.  With  a  little  practice,  one  becomes  so 
expert  in  judging  the  luminosity  that  a  reference  to  the  divided 
scale  is  seldom  necessary. 

*  Seen  best  with   transmitted  light,   a   No.    i  objective    and  a  1  inch 
eye-piece. 


378  E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES. 

You  will  then  naturally  ask,  If  these  new  binoculars  are  not 
stereoscopic,  what  is  their  use?  Their  use  is  confined  to  the 
employment  of  full  Kamsden  discs  in  each  eye,  that  is  for 
work  with  non-stereoscopic  images.  An  enormous  amount  of 
microscopic  work  is  done  with  images  of  that  kind,  and  when 
prolonged  work  is  undertaken  with  the  new  binocular  great 
relief  and  comfort  to  the  eyes  will  be  secured.  But  to  say,  on 
the  one  hand,  that  one  of  these  instruments  when  used  for, 
say,  the  examination  of  pond  life  with  a  \  inch  and  the  Mercer 
effect  is  going  to  supersede  a  Wenham,  and  on  the  other  hand 
to  state  that  by  means  of  this  new  binocular  delicate  secondary 
structures  on  diatoms  will  be  more  easily  seen  than  with  a 
monocular,  is  to  talk  nonsense.  At  the  upper  limit  they  cannot 
compete  with  the  monocular,  and  at  the  lowest  limit  they  cannot 
compete  with  the  Wenham ;  but  in  their  own  sphere  they  are 
extremely  useful  and  form  a  very  important  addition  to  the 
modern  improvements  in  Microscopy. 

At  any  time  with  the  new  binocular  the  Mercer  effect  can  be 
turned  on  to  determine  the  relation  of  the  various  parts  of  an 
object ;  but  it  must  be  borne  in  mind  that  stereoscopism  in  a 
microscope  with  the  higher  powers  is  only  partial,  and  whether 
it  is  present  or  not  depends  largely  upon  the  nature  of  the 
object;  for  example,  with  a  medium  power,  such  as  \  or  a 
i,  the  rays  of  a  Heliopelta  will  exhibit  strong  stereoscopism, 
but  many  other  objects  with  the  same  power  will  show  none. 
With  a  \  and  a  spread  slide  of  P.  angulatum,  it  is  difficult  to 
determine  whether  a  valve  is  convex  or  concave  side  up.  Stereo- 
scopism in  macroscopic  vision  differs  from  that  in  microscopic 
vision  inasmuch  as  it  is  influenced  greatly  by  the  thickness  of 
the  object. 

With  macroscopic  vision  stereoscopism  is  seen  equally  well 
with  either  a  book  or  a  bookcase,  but  that  is  not  so  with 
microscopic  vision.  In  that  case  stereoscopism  would  be  present 
with  our  allegorical  bookcase  but  not  with  the  book.  Low 
powers  deal  with  thick,  coarse  objects,  and  therefore  stereoscopism 
is  present ;  but  with  the  higher  powers  it  is  necessary  to  select 
suitable  objects  for  the  demonstration  of  the  stereoscopic  effect. 
For  instance,  bacteria  dried  on  cover  do  not  exhibit  any  more 
stereoscopism  with  the  new  binocular  than  with  a  monocular, 
for  in  a  monocular  they  can  be  made  to  look  like  sausages  ;  but 


E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES.  379 

when  bacilli  in  tissue  are  examined  with  the  Leitz  binocular,  a 
^  and  the  Mercer  method,  a  beautiful  picture  of  them  in 
perspective  projection  will  be  seen  as  well  as  of  the  cell  nuclei 
which  appear  spherical  as  marbles. 

It  is  a  good  plan  when  working  with  this  new  binocular  to 
turn  on  the  Mercer  effect  and  when  the  form  of  the  image  has 
been  mentally  grasped  to  turn  it  either  wholly  or  partly  off, 
for  when  the  stereoscopic  form  of  an  object  has  once  been 
realised  by  the  mind  re  can  be  retained,  although  the  optical 
conditions  which  gave  rise  to  it  have  been  removed.  Some  will 
have  noticed,  when  looking  at  parquetry  representing  cubes,  that 
if  the  effect  when  first  noticed  is  intaglio  it  is  a  matter  of  some 
difficulty  to  reverse  this  mental  image  so  that  the  cubes  shall 
appear  to  be  in  alto-rilievo. 

I  asked  Messrs.  Leitz  to  make  me  a  couple  of  tubes  to  slide 
over  their  tubes,  by  which  means  tube-length  adjustment  can 
be  accomplished.  The  tubes  can  be  drawn  up  and  down  over 
the  fixed  tubes  and  the  eye-pieces  also  can  be  partially  drawn 
out,  as  the  tubes  are  sprung  both  top  and  bottom.  Without 
these  tubes  it  was  not  possible  to  obtain  a  critical  image  with 
Messrs.  Leitz'  own  objectives  for  the  Continental  short  tube. 

The  great  charm  in  these  new  binoculars  consists  in  the 
sharpness  of  the  image  combined  with  ease  and  comfort  of  vision, 
hence  the  need  for  lens  correction  either  by  alteration  of  tube 
or  by  screw  collar.  The  sharpness  of  image  in  my  instrument 
at  least  is  very  little  behind  that  of  a  monocular,  for  it  requires 
a  delicate  test  to  perceive  any  difference  at  all,  and  often  a  pair 
of  18  compensating  eye-pieces  have  been  used  with  advantage. 

With  a  ^  inch  objective  and  upwards,  these  new  binoculars 
have  the  field  all  to  themselves,  as  no  other  binocular  for  sharp- 
ness and  crispness  of  image  can  for  a  moment  compete  with 
them.  With  low  powers  and  1^  inch  eye-pieces  and  a  slight 
Mercer  effect  they  give  lovely  images,  but,  as  was  hinted  above, 
with  the  Mercer  effect  one  must  alwaj^s  be  on  one's  guard  against 
hyper-stereoscopism.  Recently  a  shock  was  experienced  on  finding 
that  a  Radiolarian  which  appeared  under  the  Mercer  effect  as 
round  as  an  orange,  when  viewed  on  edge  was  shaped  rather  like 
a  mince  pie.     Here  the  Wenham  gave  the  truer  image. 

Latterry,  even  the  Greenough,  which  is  known  to  give  beautiful 
images,  has  been  suspected  of  hyper-stereoscopic  tendencies. 

Journ.  Q.  M.  C,  Series  II. — No.  75.  27 


380  E.    M.    NELSON    ON    BINOCULAR    MICROSCOPES. 

I  never  expected  to  live  to  see  a  critical  image  of  a  Podura 
scale  in  a  binocular,  but  that  is  now  an  accomplished  fact,  for  I 
have  seen  a  most  beautiful  picture  of  a  Podura  scale  with  the 
Leitz  binocular  and  an  apo  4  mm.,  and  that,  too,  critical  in  all 
azimuths. 

Dark-ground  images  are  very  suitable  for  the  new  binoculars 
because  the  objective  is  working  at  full  cone,  so  there  is  a  larger 
Ramsden  disc  than  would  be  usually  the  case  with  transmitted 
light. 

Messrs.  Leitz  sent  with  the  microscope  some  of  their  new 
Orthoskop-Kellner  eye-pieces,  the  performance  of  which  is  very 
satisfactory.  I  have  had  a  cap,  attachable  to  the  eye-piece  by  a 
small  screw,  made  to  prevent  the  eye  lens  being  smeared  by 
contact  with  the  eye-ball.  This  with  a  binocular  happens 
frequently,  so  that  a  process  of  continual  wiping  of  the  eye-lens 
is  necessary,  which  causes  interruption  and  much  interference 
with  one's  work. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  75,  November  1914. 


38] 


NOTES   ON    THE  CULTIVATION   OF   PLASMODIA   OF 

BAD  HAM  I A    UTRICULARIS. 

By  A.  E.  Hilton. 

{Head  May  26*A,  1914.) 

Fig.  6. 

A  free-flowing  mass  of  naked  and  almost  undifferentiated 
protoplasm,  such  as  we  have  in  the  plasmodium  of  Badhamia 
utricularis,  suggests  opportunities  for  biological  experiments, 
with  unusual  promise  of  success.  From  living  matter  in  so 
primitive  a  condition,  it  should  be  possible,  one  imagines,  to  gain 
a  more  intimate  knowledge  of  the  fundamental  substance  which 
is  the  basis  of  all  physical  life. 

Systematic  investigations,  however,  depend  upon  a  constant 
supply  of  material,  and  a  continuous  supply  of  plasmodia  is  not 
easy  to  obtain.  In  natural  surroundings,  they  are  only  to  be 
found  when  conditions  of  temperature  and  moisture  are  suitable  ; 
and  even  then,  in  most  districts,  they  are  very  scarce.  More- 
over, the  removal  of  a  plasmodium  to  a  place  suitable  for 
studying  it,  generally  results  in  the  plasmodium  shortly  passing 
into  the  sporangial  stage,  or  perishing  from  lack  of  proper 
nutriment.     Either  way,  the  immediate  end  is  defeated. 

In  the  Introduction  to  Mr.  Lister's  Monograph  of  the 
Mycetozoa,  recently  revised  by  his  daughter,  it  is  stated  that 
"  The  plasmodium  of  Badhamia  utricularis  is  one  of  the  very  few 
we  are  acquainted  with  that  feed  on  living  fungi,"  and  that  "  it 
is  capable  of  being  cultivated  without  limit  on  Stereum  hirsutum 
and  allied  species,  and  can  be  observed  under  the  microscope  to 
dissolve  fungus  hyphae  as  the  hyaline  border  of  a  wave  of  the 
yellow  plasmodium  advances  over  them."  In  many  places, 
however,  an  unfailing  stock  of  the  fungus  mentioned  is  difficult 
to  ensure ;  so  that  here,  again,  a  difficulty  arises. 


382  A.    E.    HILTON    ON    NOTES    ON    THE    CULTIVATION    OF 

Professor  De  Bary  (1884),  in  his  great  work  on  the  Com- 
parative Morphology  and  Biology  of  the  Fungi,  Mycetozoa  and 
Bacteria,  mentions  boiled  cabbage  leaves  as  having  been  used  for 
the  cultivation  of  Mycetozoa ;  but  he  does  not  name  the  species 
which  were  cultivated,  and  boiled  cabbage  leaves,  if  kept  for  any 
length  of  time,  become  too  offensive  for  endurance. 

In  1906,  an  account  was  published  in  Germany  of  experiments 
in  the  cultivation  of  plasmodia  made  by  J.  G.  Constantineau  ; 
and  these  are  alluded  to  both  in  Mr.  Lister's  Monograph  and 
the  Royal  Microscopical  Society's  Journal  for  April  1907.  In 
neither  of  these  are  details  given,  or  any  indication  of  the 
extent  to  which  the  experiments  were  successful.  Possibly 
they  were  too  technical  to  be  of  general  use.  ' 

No  apology,  therefore,  is  needed  for  placing  on  record  the 
result  of  experiments  made  during  the  last  few  months,  which 
suggest  a  method  of  continuous  cultivation  of  plasmodia  of 
Badhamia  utricularis,  at  once  simple  and  practicable.  Whether 
this  method,  with  or  without  modification,  is  applicable  to 
plasmodia  of  other  species,  I  have  not  had  an  opportunity  of 
<letermining.  Other  workers  may  perhaps  take  up  the  suggestion 
and  carry  the  matter  further. 

In  the  first  place,  I  have  found  that  the  growth  of  a  Plas- 
modium of  B.  utricularis  can  be  stimulated  by  the  occasional 
application  of  a  mixture  of  ammonium  phosphate  *  and  cane 
sugar,  half  an  ounce  of  the  phosphate  and  the  same  weight  of 
sugar  being  dissolved  in  a  quart  of  water. 

In  the  second  place,  I  find  that  the  plasmodium  will  feed  and 
grow  on  bread  kept  moistened  with  water,  especially  if  some  of 
the  mixture  described  be  added  to  it  from  time  to  time. 

The  effect  of  the  mixture  seems  to  be  both  direct  and  indirect- 
It  appears  to  impart  greater  vigour  to  the  plasmodium,  so 
increasing  its  feeding  capacity ;    and  it   also  benefits  the    plas- 

*  Since  the  above  paper  was  read,  Mr.  James  Grundy  has  informed  mc 
be  has  added  calcium  phosphate  to  the  mixture  with  excellent  results. 


PLASMODIA    OF    BADI1AMIA    UTRICULARIS.  383 

m odium  indirectly  by  promoting  the  growth  of  filamentous 
moulds,  such  as  Aspergillus  or  Penicillium,  which  soon  appear  on 
fungus  or  bread,  after  the  mixture  has  been  applied  to  it.  The 
hyphae  of  these  moulds  are  dissolved  and  absorbed  by  the  proto- 
plasm as  food. 

In  using  the  mixture  discretion  must  be  exercised,  according  to 
the  condition  of  the  plasmodium,  as  sometimes  plain  water  is 
preferable  ;  but  the  careful  observer  will  find  sufficient  indications 
to  guide  him  in  this  respect.  No  precise  rules  can  be  laid  down, 
but  the  student  will  find  that  with  these  auxiliary  helps  he  will 
be  less  dependent  than  heretofore  on  a  supply  of  Stereum  or 
similar  fungus,  although  it  may  be  advisable  to  use  some  of  that 
at  times,  if  convenient,  as  being  the  more  natural  food.  Any 
fungus  which  becomes  putrid  must  be  removed,  or  it  may  poison 
the  plasmodium  ;  but  the  bread  is  not  so  liable  to  become 
injurious,  and  may  remain  a  reservoir  of  protoplasm  until,  after 
a  prolonged  period,  the  plasmodium  has  eaten  it  all. 

]STote. — I  have  also  been  asked  to  describe,  for  the  benefit  of 
our  readers,  my  method  of  exhibiting  the  reversing  currents  of 
streaming  plasmodia,  a  description  of  which  has  been  given  in 
the  Journal.*  The  very  simple  arrangement  is  shown  in  the 
diagram  below. 


Fig.  6. 

A  tube  of  this  size  is  sufficient,  and  a  ring  of  blotting-paper, 
with  sclerotium  upon  it,  is  placed  inside ;  the  sclerotium  being 
between  the  paper  and  the  glass.  A  few  drops  of  water  are 
added,  the  cork  is  inserted,  and  the  tube  is  then  tilted  and 
revolved  until  the  water  has  soaked  the  paper  and  moistened  the 

*  Joum.  Q.M.C.,  Vol.  X.,  pp.  263-270,  November  1908. 


384       A.    E.    HILTON    ON    PLASMODIA    OF    BADHAMIA    UTRICULARIS. 

whole  of  the  interior  surface  of  the  tube.  A  small  hole  is  bored 
through  the  cork  to  admit  air  without  allowing  too  much 
evaporation  ;  or  the  cork  may  occasionally  be  removed.  If 
necessary,  a  drop  or  two  of  water  can  be  added  now  and  then,  to 
keep  the  air  moist.  Only  plain  water  should  be  used.  When 
the  sclerotium  revives,  the  plasmodium  creeps  on  to  the  glass  on 
either  side  of  the  ring  of  paper,  and  the  reversing  currents  can 
then  be  seen  by  placing  the  tube  on  the  stage  of  the  microscope 
and  throwing  the  light  up  through  it  from  the  mirror  beneath. 
A  1  inch  objective,  focused  on  the  veins  of  the  spreading 
plasmodium,  shows  the  streaming  movements  quite  plainly.  The 
sclerotium  should  be  placed  in  the  tube  the  day  before  the 
plasmodium  is  required  for  exhibition. 


Joarn.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  75,  November  1014. 


on  K 


85 


ON   THE   MINIMUM    VISIBLE. 

By  A.  A.  C.  Eliot  Merlin,  F.R.M.S. 

(Read  October  27th,  1914.) 

I  have  read  with  great  interest  and  profit  our  President's 
Address  on  "  Organisms  and  Origins."  The  subject  is  one  that 
must  fascinate  every  microscopist,  whatever  his  line  of  research 
may  be.  In  the  address  a  point  was  raised  respecting  the 
minimum  visible,  it  being  stated  that  "  it  seems  impossible  to 
obtain  any  precise  information  as  to  the  size  of  the  smallest 
particles  that  can  be  seen  with  the  microscope." 

Now,  setting  aside  the  ultra-microscope,  as  our  knowledge  is 
very  exact  and  definite  indeed  on  this  subject,  it  may  prove  of 
interest  to  deal  with  the  question  at  some  length.  As  a  matter 
of  fact,  when  a  particle  properly  illuminated  is  just  visible  under 
a  given  objective,  if  the  aperture  be  cut  down  by  means  of  an  iris 
diaphragm  placed  above  the  back  lens  so  that  the  particle  just 
ceases  to  be  visible,  and  the  numerical  aperture  to  which  the 
objective  has  been  thus  reduced  is  measured,  then  the  dimensions 
of  the  particle  can  be  exactly  ascertained  from  the  antipoint  table 
published  by  Mr.  Nelson  in  the  Journal  of  the  Royal  Microscopical 
Society.  This  antipoint  table  should  prove  invaluable  when 
accurate  and  minute  measurements  are  necessary,  but  little 
interest  has  been  apparently  evinced  in  the  matter  since  micro- 
metry of  a  high  order  is  no  longer  practised,  in  England  at  least. 
Leaving  this  for  the  present,  I  venture  to  refer  to  and  examine 
the  claim  made  by  Mr.  Brown  at  a  recent  meeting  of  the  Club 
that  he  had  seen  central  "  pores  "  on  the  surface  of  the  frustules 
of  certain  diatoms ;  which  he  estimated  at  l/200,000th  of  an  inch 
in  diameter.  On  reading  Mr.  Brown's  "  Notes  on  the  Structure 
of  Diatoms,"  *  I  examined  a  specimen  of  Pleurosigma  balticum, 

*  Journ.  Q.M.C.,  Ser.  2,  Vol.  II.  p.  317. 


386  A.    A.    C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE 

in  realgar,  under  a  very  perfect  recent  1/1 2th  apochromat  of 
N.A.  1*4,  employed  with  a  magnification  of  4,200.  Mr.  Brown's 
central  "pores"  could  be  readily  distinguished  at  a  certain  high 
focus  on  the  outer  layer  of  the  valve.  But  in  the  "  pores  "  so 
revealed  I  immediately  recognised  my  old  friends  Dr.  Boyston- 
Pigott's  "  dark  eidolic  dots  of  interference."  In  thus  frankly 
stating  my  conviction,  I  am  sure  that  Mr.  Brown,  as  a  veteran 
observer,  would  wish  me  to  pursue  no  other  course.  We  are  all 
liable  to  make  mistakes  in  the  interpretation  of  diatomic  struc- 
ture, and  the  only  hope  of  progress  lies  in  friendly  criticism  and 
the  exchange  of  views.  Although  I  consider  Mr.  Brown's  central 
"  pores  "  of  Pleurosigma  balticum,  Navicula  serians  and  P.  angu- 
lation! to  be  clearly  false  ghosts,  it  is  by  no  means  unlikely  that 
the  outer  layers  of  these  diatoms  may  be  perforated  with  fine 
secondary  structure,  like  the  forms  with  coarser  primaries. 
Under  the  most  critical  conditions,  with  T4  N.A.  and  a  magnifi- 
cation of  4,200,  something  of  the  kind  has  been  seen  both  in 
P.  balticum  and  N.  serians.  These  appearances,  however,  are 
far  more  elusive  and  difficult  than  the  eidolic  central  clots,  and 
quite  different  in  aspect  and  position.  So  far  as  my  experience 
goes,  capped  diatomic  primaries  are  always  pierced  by  at  least 
three  or  four  secondaries  when  any  such  structure  is  observable. 
It  may  nevertheless  be  safely  asserted  that  if  the  primaries  of 
P.  angulatum  are  thus  capped  and  pierced,  the  secondaries  must 
be  as  much  beyond  the  grasp  of  our  best  lenses  as  are  the  eidolic 
dots  of  A .  pellucida. 

In  order  to  show  how  similar  are  the  observational  conditions 
described  by  Dr.  Royston-Pigott  as  necessary  for  the  proper 
demonstration  of  eidolic  clots  to  those  specified  by  Mr.  Brown 
concerning  his  central  diatomic  "  pores,"  I  must  quote  Dr.  Royston- 
Pigott's  remarks  on  the  subject  at  some  length.  In  "Micro- 
scopical Advances  "  *  it  is  stated :  "  With  regard  to  attenuated 
circles,  nothing  are  more  abundant  in  diatomic  and  scale 
markings.  If  a  spherule  be  l/60,000th  of  an  inch,  the  black 
marginal  ring  is  generally  about  one-fifth  of  this,  or  1 /300,000th 
thick,  ornamented  with  a  minute  central  black  clot.  The  clot  and 
its  fellows  are  amongst  the  most  interesting  and  surprising  sights 
in  minute  microscopy.     Few   glasses  will  show  them.     That   a 

*  English  Mechanic,  vol.  xlviii.  p.  209. 


A.    A.    C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE.  387 

minute  spherule  should  be  capable  of  exhibiting  the  same 
recherchcs  phenomena  as  a  delicate  glass  lens  l/30th  focus  solely 
from  its  refractions  and  chromatic  aberrations,  at  first  seems 
quite  incredible."  In  another  place  *  Dr.  Poyston-Pigott  con- 
tinues :  "  The  existence  of  dark  eidolic  dots  of  interference  is  an 
important  fact  which  now  requires  further  elucidation.  Darkness 
has  resulted  from  excessive  light.  Wave  neutralising  wave,  certain 
undulations  killed  each  other.  This  is  seen  on  a  grand  scale  in 
the  solar  spectra  formed  by  a  small  lens  in  the  foci  of  a  very  fine 
microscojDe.  Forty-eight  dark  rings  have  been  counted  developed 
by  an  extremely  small  solar  beam.  The  feeble  refractions  occur- 
ring in  a  diatomic  convexity  cannot  develop  a  very  numerous 
retinue  of  rings  ;  but  sufficient  diatomic  lenses  have  been  accumu- 
lated for  the  purpose  indicated.  To  exhibit  successfully  a  series 
of  eidolic  dots  of  interference  demands  very  careful  illumination 
and  a  very  fine  objective.  Their  size  varies  with  the  nature  and 
diameter  of  the  refracting  spherule.  The  1/Sth  water  lens  of 
Powell  and  Lealand  seems  to  excel  all  my  others  in  detecting 
them  in  different  focal  planes.  Six  have  been  in  order  thus  seen, 
but  in  small  spherules  such  as  those  of  P.  angtdatum  many  dots 
are  too  faint  for  recognition.  My  experience  of  scale  molecules 
has  convinced  me  they  also  are  wonderfully  transparent,  display 
black  marginal  test  rings,  and  often  one  eidolic  dot."  .  .  .  "  These 
dots  are  well  developed  by  large  beading  of  diatoms  from  1/9, 000th 
to  1/1 4,000th  of  an  inch  in  diameter.  Extremely  large  spherical 
beads  are  seen  in  Cresswellia  superba  and  in  Cestodiscus  superbus 
(beads  1/1 2,500th)  ;  E.  costatus  and  C  oscinodisens  radiatus  are 
also  fine  examples.  To  exhibit  successfully  all  the  eidolic  dots  of 
interference  in  successive  focal  planes  demands  very  excellent 
glasses,  careful  precautions,  and,  above  all,  well-separated  diatomic 
beads.  They  may  be  caught  above  very  small  diatomic  and  scale 
beading.  Remarkably  good  eyesight  has  distinguished  them 
above  the  bosses  of  P.  angulation  and  occasionally  I  have 
detected  two  sets  of  dots  when  one  stratum  of  beading  lies  just 
below  another.  In  general,  except  in  strongly  pronounced 
diatomic  bosses,  the  observer  may  rest  satisfied  with  finding  the 
primary  eidolic  dot,  No.  1,  fig.  1  in  the  diagram. f     A  better  glass 

*  English  Mechanic,  vol.  xlix.  p.  315. 

t  A  diagram  showing  a  series  of    eight    gradually  diminishing  dots  is 
annexed  to  the  original  paper. 


388  A.    A.    C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE. 

may  enable  him  to  detect  Nos.  2  and  3  by  daylight.  Lamplight, 
unless  its  yellow  tint  be  subdued  with  a  blue  chimney  and  other 
blue  glasses,  extinguishes  the  dot  by  the  flame  image  produced  by 
the  diatomic  lens.  It  may  be  recovered,  however,  in  front  of  it 
by  careful  manipulation."  ..."  Dr.  Van  Heurck  obligingly 
photographed  with  the  new  apochromatic  glass  the  eidolic  dot 
shown  by  the  beading  of  P.  angulatum." 

Dr.  Royston-Pigott  estimates  the  dots  in  P.  angulatum  to  be 
attenuated  to  1 /250,000th  of  an  inch  and  considers  that 
extremely  minute  dots,  about  1/300, 000th,  are  not  only  found 
amongst  diatoms,  but  reveal  themselves  in  the  transparent 
headings  of  moth-scales,  and  adds,  "  but  there  are  many  forms 
of  these  dots."  It  is  also  remarked  that  "  exquisitely  small  and 
black  dots  can  often  be  seen  in  focal  planes  elevated  slightly 
above  diatomic  beads  by  using  a  black  central  stop  below  the 
condenser.  It  requires  very  grand  glasses  to  display  these  elegant 
results."  It  is  needless  to  point  out  that  the  late  Dr.  Royston- 
Pigott  was  an  upholder  of  the  now  abandoned  view  that  the 
perforations  of  diatoms  were  solid  silex  beads  or  bosses.  The 
foregoing  sufficiently  proves  that  the  central  eidolic  dots  or 
"  pores "  of  diatoms  were  well  known  twenty-six  years  ago,  but 
those  specially  interested  in  the  subject  should  read  the  papers 
referred  to. 

Setting  aside  all  such  diffraction  phenomena,  or  false  ghosts, 
probably  the  most  delicate,  true  diatomic  structures  just  within 
the  grasp  of  our  finest  modern  objectives  of  large  aperture  are 
the  thin  perforated  "  veils  "'  to  be  detected  on  certain  diatoms. 
Of  these  perhaps  one  of  the  best  examples  is  Triceratium  america- 
nitm,  var.,  Oamaru,  mounted  in  styrax  by  M oiler.  It  is  a  difficult 
structure  with  axial  screen  illumination,  but  there  can  be  little  or 
no  doubt  that  the  appearances  observable  represent  real  perfora- 
tions in  a  thin  outer  plate.  In  this  diatom  there  is  no  complicated 
structure  to  bewilder  the  observer  and  manufacture  false  ghosts. 
It  is,  however,  extremely  improbable  that  the  minute  perforations 
of  the  IViceratium  americanum,  difficult  as  they  are,  represent 
anything  smaller  than  the  1/1 00,000th  of  an  inch,  and  being 
subject  to  the  limitations  of  the  laws  of  diffraction,  like 
all  periodic  structures,  are  consequently  of  little  help  as 
an  example  of  the  minimum  visible  under  more  favourable 
conditions. 


A.    A.    C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE.  389 

In  biological  investigations  it  is  frequently  required  to  view 
widely  scattered  living  particles,  or  germs,  of  various  sizes  down 
to  the  most  minute  dot  that  can  just  be  detected.  When  any 
such  particle  is  under  observation  nothing  is  easier  than  to 
measure  its  dimensions  accurately  by  the  anti point  method. 
There  is  in  my  cabinet  a  section  of  fluor  spar,  given  to  me  by 
Mr.  Traviss,  which  contains  numerous  liquid-filled  cavities  of 
various  sizes.  In  each  cavity  there  is  a  rapidly  moving  bubble. 
Some  of  these  bubbles,  under  a  1/1 2th  apochromat  of  1*4KA., 
appear  as  mere  trembling  specks  only  just  visible  and  within  the 
grip  of  the  objective,  and  there  are  probably  others  too  minute 
to  be  seen  at  all.  Selecting  a  bubble  just  visible  under  such 
conditions  when  illuminated  with  a  large  axial  cone  and  Gifford 
screen,  if  we  wish  to  ascertain  its  diameter  we  have  only  to  refer 
to  Mr.  Nelson's  papers,  "A  Micrometric  Correction  for  Minute 
Objects,"  *  and  "  The  Influence  of  the  Antipoint  on  the  Micro- 
scopic Image  shown  graphically."  f  These  papers  contain  all 
the  necessary  explanations  and  data,  and  we  find  from  the 
amended  table  in  the  latter  paper  that  with  a  working  aperture 
of  1*4  and  screen  the  minimum  particle  visible  must  have  a 
diameter  of  0-00000265  (l/377,358th)  in.,  or  0'0673  /x  :  the  photo- 
graphic limit  being  with  similar  aperture  0-00000209  (l/478,4:69th) 
in.,  or  0'5031  /x. 

Thus  we  can  measure  accurately  the  diameter  of  the  smallest 
particle  or  bubble  visible  with  a  given  aperture.  The  accuracy 
of  the  result  depends  on  knowing  exactly  the  N.A.  employed  at 
extinction  point,  and  this  must  in  each  case  be  found  with  an 
accurate  apertometer.  It  is  advisable  that  the  working  aperture 
should  nearly  equal  the  N.A.  of  the  objective  at  the  extinction 
point,  but  it  need  not  necessarily  be  quite  full  cone.  When  the 
critical  point  is  reached  a  very  slight  decrease  of  N.A.  makes  all 
the  difference  between  easy  visibility  and  invisibility.  Mr. 
Nelson's  first  table  "  was  computed  by  the  formula 


5-4686  \  W.A. 
The  numerical  coefficient  was  determined  from  data  found  by  the 

*  Journ.  R.M.S.,  1903,  pp.  579-82. 

t  Ibid.,  1904,  pp.  269-71.     See   also   "  On   the    Measurement  of  Very- 
Minute  Microscopical  Objects  "  {Journ.  R.M.S.,  1909,  pp.  549-50). 


390  A.    A.    C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE 

extinction  of  the  image  of  a  minute  point  by  reducing  the  W.A. 
to  0'165.  The  size  of  the  point  was  measured  by  a  wide-angled 
oil-immersion,  and  a  W.A.  of  0*9,  and  was  found  to  be  apparently 
1/50, 050th  inch.     From  this  we  have 

6-6961X-165  =  50,050. 
And 

:0-000003663. 


li-6961\-9 


Employing  this  as  a  provisional  correction,  we  find  the  size  of  the 
point  to  be  1/4 2,396th  in.  Again,  using  this  measurement,  we 
obtain  a  new  numerical  coefficient,  viz.  5*6587,  and  finally  find 
the  size  of  the  point  1/40, 875th  in.,  and  the  coefficient  5*4686  as 
stated  above.  In  this  calculation  A  is  the  reciprocal  of  the  wave- 
length, or  the  number  of  waves  per  inch,  given  at  the  head  of 
each  column  in  the  table."  In  Mr.  Nelson's  subsequent  paper, 
"  The  Influence  of  the  Antipoint  on  the  Microscopical  Image 
shown  graphically,"  the  data  will  be  found  for  the  slightly 
amended  table  given  therein. 

Shortly  after  the  publication  of  Mr.  Nelson's  papers  on  this 
interesting  subject,  Dr.  Coles  kindly  sent  me  a  well-stained 
balsamed  slide  of  the  putrefactive  microbe  B.  termo.  On  this  I 
was  able  to  find  a  distinctly  flagellated  specimen  suitable  for 
measurement  by  the  extinction  method.  The  flagellum  could  be 
plainly  seen  with  an  apochromatic  l/6th  of  0*98  N.A.  used  with 
a  full  cone  and  screen,  and  it  became  invisible  when  the  N.A. 
was  gradually  cut  down  to  0*42  by  means  of  an  iris  diaphragm 
over  the  top  lens  of  the  objective,  thus  making  the  diameter  of 
the  flagellum  0*00000S91  (1/1 1 2,200th)  in.,  or  0*226  fx. 

Afterwards  a  balsamed-stained,  flagellated  specimen  of  the 
tubercle  bacillus  was  found.  This  was  more  difficult  to  see,  and 
the  flagellum  was  thought  to  be  much  finer  than  that  of  the 
B.  termo.  A  1/8 tli  apochromat  of  1*4  N.A.  was  employed  to 
measure  this.  When  the  N.A.  was  cut  down  to  the  vanishing 
point  and  tested  with  the  Abbe  apertometer,  it  was  found  to  bv 
exactly  0*42,  thus  making  the  diameter  of  the  tubercle  bacillus 
flagellum  precisely  equal  to  that  of  the  B.  termo.  It  may  here 
be  mentioned  that  the  existence  of  the  tubercle  bacillus  flagellum, 
discovered  by  Mr.  Nelson,  has  been  denied.      It  has,  however, 


A.    A     C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE.  391 

been  observed  by  many  microscopists,  including  myself,  and  has 
been  beautifully  photographed  by  Mr.  Nelson.* 

Now  the  flagellum  of  B.  termo  was  most  carefully  measured 
by  the  late  Dr.  Dallinger,  and  his  results  were  embodied 
in  a  paper  entitled  "  On  the  Measurement  of  the  Diameter 
of  the  Flagella  of  Bacterium  termo  :  a  Contribution  to  the 
Question  of  the  '  Ultimate  Limit  of  Vision  '  with  our  Present 
Lenses."  f  Two  hundred  measurements  were  made  by  means  of 
a  fine  pencil  mark  made  over  half  or  two-thirds,  not  over  the 
whole,  of  the  camera-lucida  image  of  the  flagellum.  The  labour 
entailed  may  be  judged  from  Dr.  Dallinger's  statement:  "Now 
I  made  fifty  separate  drawings  and  measurements  with  each 
of  the  four  lenses,  the  same  conditions  being  observed  in  each 
case.  The  results  expressed  in  decimal  fractions  are  as  follows, 
viz.  : 

"  1.  The  mean  value  of  fifty  measurements  made  with  the 
1/1 2th  in.  objective  gives  for  the  diameter  of  the  flagellum 
000000489208. 

"  2.  The  mean  value  of  fifty  measurements  made  with  the 
l/16th  in.  objective  gives  0-00000488673. 

"  3.  The  mean  value  of  fifty  measurements  made  with  the 
l/25th  in.  objective  gives  0-00000488024. 

"  4.  The  mean  value  of  fifty  measurements  made  with  the 
l/35th  in.  objective  gives  0-00000488200. 

"  We  thus  obtain  a  mean  from  the  whole  four  sets  of  measure- 
ments, which  gives  for  the  value  of  the  diameter  of  the  flagellum 
of  B.  termo  0*00000488526,  which,  expressed  in  vulgar  fractions, 
is  equivalent  to  1 /204700th  of  an  inch  nearly;  that  is  to  say. 
within  a  wholly  inappreciable  quantity." 

These  classical  measurements  of  the  diameter  of  the  B.  termo 
flagellum  are  of  the  greatest  importance,  for  by  their  means  the 
accuracy  of  the  extinction  method  is  demonstrated,  which  in  turn 
serves  to  confirm  the  exactness  of  the  late  Dr.  Dallinger's  results. 
Assuming  that  a  W.A.  of  0  8  was  employed,  the  necessary  anti- 
point  correction  by  Mr.  Nelson's  amended  table  is 0*000005 13th  in., 
which,addedtoDr.Dallinger'smean,makes0*00001001(l/99,900th) 
in.  for  the  true  diameter  of  the  flagellum,  as  against  0*00000891 

*  Journ.  Q.M.C.,  Ser.  2,  Vol.  XI.  PI.  22. 
f  Ibid.,  1878,  pp.  109-75. 


392  A.    A.    C.    ELIOT    MERLIN    ON    THE    MINIMUM    VISIBLE. 

(1/1 12,200th)  in.,  the  diameter  obtained  by  me  from  Dr.  Coles's 
specimen  by  extinction  measurement.  The  latter  method  is 
certainly  not  second  to  Dr.  Dallinger's  in  exactness,  whileit  is 
undoubtedly  less  laborious.  Through  no  fault  of  his  own,  Dr. 
Dallinger's  uncorrected  figures  put  the  diameter  of  the  flagellum 
at  half  its  true  dimensions. 


Journ.  Quekett  Microtcopical  Club,  Ser.  2,  Vol.  XII.,  No.  75,  November  1014. 


39:; 


REMARKS   ON    TWO   SPECIES  OF   AFRICAN    VOLVOX. 

By  Charles  F.  Eousselet,  F.R.M.S. 
(Read  October  21th,  1914.) 

The  slides  of  two  species  of  African  Volvox  which  I  am 
exhibiting  to-night  have  a  history  of  unusual  interest. 

It  will  be  remembered  that  at  the  meeting  of  this  Club  on 
October  25th,  1910,  a  paper  was  read  by  Prof.  G.  S.  West  of 
Birmingham  University,  in  which  two  new  species  of  Volvox 
from  Africa  were  described. 

One  of  these,  Volvox  africames,  of  small  size  and  oblong  in 
shape,  was  found  in  a  Plancton  collection  made  in  July  1907 
by  Mr.  R.  T.  Leiper,  of  the  Egyptian  Government  Survey,  near 
the  northern  shores  of  the  Albert  Nyanza.  I  received  a  very 
small  quantity  of  this  collection  for  the  purpose  of  determining 
the  Rotifera  it  contained,  and  found  these  pretty  oval  colonies  of 
Yolvox,  as  did  also  Prof.  West,  who  had  received  a  similar 
sample,  in  order  to  name  the  various  fresh-water  algae 
contained  therein. 

The  other  species  is  of  very  much  larger  size  (as  much  as 
l/20th  inch  in  diam.),  of  spherical  shape  and  densely  crowded  with 
cells  on  its  surface  (estimated  at  50,000  cells  in  one  of  the  larger 
Colonies),  was  found  by  myself  on  the  occasion  of  the  visit  of  the 
British  Association  to  South  Africa  in  September  1905  at 
Gwaai  Station  in  Rhodesia,  about  half-way  between  Bulawayo 
and  the  Victoria  Falls  of  the  Zambesi ;  the  train  stopped  for 
half  an  hour  at  this  station  by  the  side  of  a  shallow  pool  formed 
by  the  Gwaai  River,  and  as  usual  I  jumped  out  of  the  train  with 
my  collecting- net  and  bottle  and  secured  a  dip  from  the  pool. 
As  the  train  went  on  I  examined  the  contents  of  my  bottle,  and 
besides  various  Rotifera  I  noticed  some  large  colonies  of  Volvox. 
The  whole  collection  was  put  up  in  formalin,  and  eventually  the 
specimens  of  Volvox  were  handed  over  to  Prof.  West  for 
description,  which  was  done  in  our  Journal  in  November  1910.* 

Of  both  these  African  Species  of  Volvox  vegetative  colonies 
only  had  been  found,  and  Prof.  West  expressed  his  regret  that 
the  sexual  colonies  in  various  stages  were  not  represented,  so 
that  his  description  was  necessarily  incomplete. 

This  closed  the  first  stage  of  the  story. 

In  May  1912  Dr.  A.  W.  Jakubski  published  in  the  Zoologischer 
Anzeiger  a  paper  on  Rotifera  collected  by  him  in  the  Ussangu 
Desert  in  German  East  Africa,  in  which  several  new  species  of 
Distyla  were  figured  and  described.  At  that  time  Mr.  James 
Murray  was  writing  papers  on  the  Rotifera  of  Australasia  and 
South  America  and  in  particular  was  studying  the  family  of  the 

*  Journ.  Q.M.C.,  Ser.  2,  Vol.  XL,  p.  99-104. 


O 


94       C.    F.    ROUSSELET    ON    TWO    SPECIES    OF    AFRICAN    VOLVOX. 


Cathypnidae,  and  we  considered  it  very  desirable  to  obtain, 
if  possible,  specimens  of  the  new  species  described.  So  after  I 
had  ascertained  that  the  author  was  working  at  the  Zoological 
Institute  at  Lemberg  University  I  wrote  to  Dr.  Jakubski 
asking  him  to  be  good  enough  to  send  me  a  little  of  the  material 
containing  the  species  of  Rotifera.  Some  time  in  the  spring  of 
1913  the  Doctor  very  kindly  sent  a  few  slides  and  also  about  eigh- 
teen tubes  of  Plancton  material  collected  in  German  East  Africa. 
By  this  time  Mr.  James  Murray  had  left  England  on  his  way  to 
the  disastrous  North  Canadian  Arctic  Expedition,  from  which 
he  has  not  returned,  and  being  myself  much  occupied  with  other 
work,  1  delayed  the  examination  of  this  material  until  the  spring 
of  the  present  year,  when  I  received  a  polite  reminder  from  the 
sender  asking  for  the  return  of  his  tubes  as  soon  as  convenient. 
This  request  obliged  me  to  look  over  the  contents  of  the  tubes 
without  further  delay,  which  was  clone  in  May  and  June  last. 

In  his  paper  the  author  states  that  in  deserts  of  German 
East  Africa  pools  and  ponds  are  rare  and  can  only  be  found  after 
heavy  rainfalls,  and  are  then  shallow  and  last  a  very  few  weeks 
only,    but   often   develop    a    considerable    amount    of    Plancton 


organisms. 


In  two  of  the  tubes,  amongst  various  Rotifera,  I  was  surprised 
and  fortunate  to  come  across  numerous  colonies  of  Vol  vox 
which  I  at  once  recognised  as  the  same  two  species  from 
Africa  described  by  Prof.  West  four  years  previously.  Moreover 
both  species  were  present  in  various  sexual  stages  with 
androgonidia  and  oospores,  the  male  and  female  colonies,  as 
well  as  the  vegetative  colonies.*  The  ripe  star-shaped  oospores 
of  the  large  Volvox  Rousseleti  in  particular  are  very  fine  and 
remarkable,  and  these  specimens  will  now  enable  Prof.  West 
to  describe  the  complete  life- history  of  both  these  African  species, 
which  appear  to  be  widely  distributed  in  that  continent,  though 
not  as  yet  known  from  any  other  part  of  the  world. 

After  completing  my  examination  of  the  material  I  returned 
all  the  tubes  to  Dr.  Jakubski  at  Lemberg  in  Galicia  early  in 
July,  but  have  not  heard  whether  they  reached  him.  The 
tragedy  of  the  situation  is  that  at  the  end  of  the  same  month 
war  was  declared  and  Lemberg  (Lwow)  was  one  of  the  first 
towns  of  importance  taken  and  occupied  by  the  Russian  army, 
and  it  is  at  present  impossible  to  ascertain  what  has  become  of 
either  my  correspondent  or  his  collection  of  specimens. 

You  will  agree  that  it  was  a  piece  of  extraordinary  and 
remarkable  good  luck  that  these  collections  came  into  my  hands 
and  at  this  particular  time. 

*  Slides  were  exhibited  by  Mr.  Eousselet  showing  the  various  sexual 
stages. 

Joum.  Quekctt  Microscopical  Club,  Her.  2,  Vol.  XII. ,  No.  75,  November  1914. 


395 


REPORT  ON  THE  CONFERENCE  OF  DELEGATES  OF 
CORRESPONDING  SOCIETIES  (BRITISH  ASSOCI- 
ATION) HELD  AT  HAVRE,  1914,  BY  INVITATION  OF 
THE  ASSOCIATION  FRANCAISE  POUR  L'AVANCE- 
MENT   DES  SCIENCES. 

{Bead  October  27th,  1914.) 

To    the    President    and    Council    of   the    Quehett    Microscopical 
Club,  London. 

As  your  Delegate  I  attended  the  Havre  Congress  of  the 
French  Association,  which  began  on  Monday,  July  27th.  The 
Opening  Meeting  was  held  in  the  Grand  Theatre,  where  Monsieur 
Armand  Gautier,  the  President,  welcomed  the  members  and 
delivered  an  address.  On  behalf  of  the  English  members 
Sir  William  Ramsay  addressed  the  meeting  in  French.  In  the 
evening  there  was  a  reception  by  the  Mayor  and  Corporation 
in  the  Town  Hall.  On  the  Tuesday  I  attended  a  Conference 
of  the  Delegates  of  Corresponding  Societies  in  the  Town  Hall, 
when  Sir  E.  Brabrook  read  a  discourse  on  behalf  of  the  Chair- 
man, Sir  H.  G.  Fordham,  who  was  absent,  "  On  the  History 
of  British  Association  Conferences  of  the  Delegates,"  of  which 
it  appears  Mr.  John  Hopkinson  was  the  founder.  Mr.  Hop- 
kinson  read  a  paper  on  "Local  Natural  History  Societies  and 
their  Publications,"  in  which  he  advocates  certain  rules  in 
the  publication  of  Transactions  which  would  render  them  more 
easily  capable  of  being  referred  to  and  quoted  by  inquirers 
or  the  bibliographer,  and  at  the  same  time  save  expense  in 
making  reprints  for  distribution  by  the  authors. 

Sectional  Meetings  took  place  on  the  Tuesday  and  Wednesday, 
although  clouds  were  then  gathering  on  the  political  horizon,  and 
some  presidents  of  Sections  did  not  appear.  On  the  Thursday, 
July  30th,  the  Congress  went  on  an  excursion  by  train  and 
boat  up  the  River  Seine  as  far  as  Rouen,  visiting  many  historical 
places  of  interest  and  some  famous  old  and  ruined  cathedrals 
and  ancient  Roman  settlements,  such  as  Lillebonne,  Caudebec, 
Jumieges,  La  Bouille,  on  the  way. 

On  the  following  day,  Friday,  more  meetings  of  Sections  wTere 
Journ.  Q.  M.  C.,  Series  II.— No.  75.  28 


396  REPORT  ON  THE  CONFERENCE  OF  DELEGATES  HELD  AT  HAVRE. 

held,  but  were  very  poorly  attended,  as  the  political  outlook  was 
more  and  more  threatening  and  many  members  were  called  away 
and  left  hurriedly. 

On  Saturday,  August  1st,  most  presidents  and  secretaries  of 
Sections  had  gone  and  only  a  very  few  meetings  took  place.  On 
that  morning  at  the  Zoological  Section  I  read  a  short  paper 
in  French  on  "  Pedalion  or  Pedalia,  a  Question  of  Nomenclature 
in  the  Class  Potifera."  About  midday  a  Government  announce- 
ment or  "  Decret "  was  placarded  at  the  Town  Hall  and  at 
Post  Offices  ordering  a  general  mobilisation  of  the  French  Army,, 
to  commence  at  midnight,  when  the  Congress  broke  up. 

I  left  Havre  the  same  night  by  steamer  for  Southampton  r 
where  I  arrived  on  Sunday  morning,  about  three  hours  late,  the 
boat  having  been  held  up  several  times  in  the  Channel  by 
torpedo-boats.  Thus  ended  a  most  tragic  meeting  of  a  Congress 
for  the  Advancement  of  Science. 

(Signed)  Charles  F.  Pousselet. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  75,  November  1914. 


o\n 


PEDALION    OU    PEDALIA;    UNE   QUESTION    DE 
NOMENCLATURE    DANS   LA   CLASSE  DES  ROTIFERES. 

Par  Charles  F.  Rousselet. 

[Paper  read  by  the  author  as  the  Queliett  Club'' a  Delegate  to  the  Conference 
of  Delegates  of  Corresponding  Societies  of  the  British  Association  held  at 
Havre  by  invitation  of  the  Association  Franqaise  pour  V  Avancement  des 
Sciences.     Section  de  Zoologic,  Seance  du  ler  A  out  1914.] 

Au  6me  Congres  de  l'Association  Frangaise  pour  l'Avancenient 
des  Sciences  term  au  Havre  en  18"7  M.  Jules  Barrois  presenta 
un  memoire  portant  le  titre:  "Sur  1'anatomie  et  le  developpement 
du  Pedalia  mira."  (Seance  de  la  Section  de  Zoologie  du30Aoiit 
1877.) 

Or  en  1871  le  Dr.  C.  T.  Hudson  avait  decouvert  dans  une  mare 
d'eau  douce  a  Clifton  pres  de  Bristol  un  Kotifere  extraordinaire, 
ayant  six  membres  arthropodiques,  l'un  sur  la  face  ventrale,  un 
second  sur  la  dorsale,  et  deux  de  chaque  cote  du  corps,  au  moyen 
desquels  1'aniinal  peut  nager  et  avance  dans  l'eau  par  petits 
sauts,  semblables  aux  mouveruents  des  larves  des  crustaces 
Cyclops.     Hudson  noinma  l'animal  Pedalion  mirum. 

En  examinant  ces  jours  le  volume  des  Comptes  rendus  du 
Congres  de  1877  j'y  trouve  a  la  page  661  un  Extrait  de  la  com- 
munication de  Barrois  portant  le  titre  ci-dessus.  On  voit  que  le 
nom  de  Pedalion  a  ete  change  en  celui  de  Pedalia.  En  lisant 
plus  loin  on  y  trouve  les  phrases  suivantes : 

"  M.  J.  Barrois  a  ete  conduit  par  ses  etudes  sur  les  Bryozoaires 
a  considerer  la  forme  primitive  de  ces  animaux  comme  comparable 
a  l'etat  adulte  des  Botiferes.  Pour  elucider  cette  question 
M.  Barrois  a  entrepris  au  laboratoire  de  Wimereux  l'etude  de 
l'embryogenie  du  genre  Pedalion  si  interessant  par  la  diversity  de 
ses  organes  appendiculaires  et  dont  une  espece  est  assez  commune 
a  Wimereux.  Ce  Pedalion  est  une  espece  marine.  II  presente, 
outre  les  deux  epaulettes  ciliees,  six  lambeaux  d'epithelium 
ciliaire  qui  forment  par  leur  reunion  une  couronne  presque  com- 
plete; les  organes  appendiculaires  de  la  face  orale  sont  au  nombre 
de  six  :  quatre  pointes  chitineuses  et  deux  boutons  a  cils  raides ; 
les  points  oculiformes  sont  au  nombre  de  trois,  dont  deux 
appartiennent  a  la  face  orale." 

On  voit  que  le  nom  de  Pedalion  est  mentionne  deux  fois  dans 
cet  extrait,  tandis  que  celui  de  Pedalia  n'y  est  pas  nomme  du 
tout,  ni  y  trouve-t-on  une  raison  quelconque  pour  ce  changement 
de  nom,  qui  se  trouve  uniquement  dans  le  titre  du  memoire  de 
M.  Barrois. 


398  C.    F.    ROUSSELET    ON    PEDALION    OU    PEDALTA. 

La  question  done  s'impose :  qui  a  ecrit  ce  titre  ?  est-ce 
M.  Barrois,  ou  le  redacteur  des  Comptes  rendus  du  Congres  ? 
J'ignore  si  le  memoire  de  Barrois  a  ete  publie  en  entier  quelque 
part,  et  je  serai  bien  content  d'en  etre  informe.  La  Revue 
Scientifique  du  temps  (No.  13,  du  29.  Sept.  1877)  a  publie  le 
merne  extrait,  sans  le  titre  cepenclant,  et  par  consequent  le  mot 
Pedalia  n'y  est  pas  mentionne,  mais  seulement  celui  de  Pedalion 
a  deux  fois. 

II  y  a  autre  chose  encore  :  par  la  description  que  donne  Barrois 
il  ressort  bien  clairement  que  son  Botifere  n'etait  pas  Pedalion, 
qui  ne  vit  pas  dans  la  mer,  n'a  que  deux  yeux,  n'a  pas  d'epaulettes 
ciliees,  ni  de  couronne  ciliee  en  six  lambeaux,  ni  six  organes 
append icul aires  sur  la  face  orale.  Toute  cette  description 
s'applique  parfaitement  a  tine  espece  marine  du  genre  Syncbaeta 
(probablement  S.  triophthalma  Lauterborn,  qui  porte  ses  ceufs 
suspendus  a  la  pointe  de  son  pied  en  nageant),  mais  pas  du  tout 
au  Pedalion  mirum  de  Hudson,  qu'on  rencontre  un  peu  partout 
en  ete  dans  des  mares  d'eau  douce. 

II  existe  deux  autres  especes  de  Pedalion  (P.  fennicum  Levander 
et  7-*.  oxyure  Sernow)  qui  se  trouvent  tous  deux  dans  les  eaux 
saum  aires  en  Asie,  en  Egypte,  en  Amerique  et  en  Australie, 
mais  aucune  espece  n'a  encore  ete  decouverte  en  mer. 

Par  suite  de  1'application  des  regies  internationales  de  nomen- 
clature le  nom  du  genre  Pedalion  doit  tomber,  ce  nom  ayant  ete 
applique  precedemment  a  un  poisson  (Swainson  1832),  et  a  un 
mollusque  (Solier  1847). 

II  est  done  utile  et  necessaire  de  rechercher  qui  a  le  premier 
employe  le  nom  de  Pedalia,  et  j'invite  les  membres  de  la  Section 
de  Zoologie  de  bien  vouloir  me  communiquer  le  memoire  complet 
de  M.  Jules  Barrois  s'il  existe,  ou  toute  autre  information  qui 
pourrait  elucider  cette  question. 

Je  ne  parle  pas  de  l'Hexarthra  de  Schmarda,  qui  pourrait 
tres  bien  etre  une  espece  encore  plus  ancienne  de  Pedalion ;  e'est 
une  autre  question  que  j'espere  pouvoir  resoudre  sous  peu,  apres 
m'avoir  procure  des  peches  dans  le  meme  marais  d'eau  saumatre 
a  El  Kab  en  Egypte  oil  Schmarda  a  decouvert  son  Hexarthra  en 
Mars  1853. 

II  resulte  de  cet  expose  que  M.  Jules  Barrois  (ou  peut-etre 
quelqu'autre  personne)  a  non  seulement  change  le  nom  de 
Pedalion  en  celui  de  Pedalia,  mais  encore  l'a  applique  a  un 
Svnchaeta. 


Joarn.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  75,  Koccmbc,- 1914. 


399 


THE    LIBRARY. 

BOOKS   PURCHASED    SINCE   JANUARY    1914. 

Optical  Convention.     Vol.  II.     1912. 

Sylloge    Algarum    Omnium.      Vol.    II.     Sect.    II.      J.    Bapt. 

De  Toni,  1892. 
Bacteriological    Examination    of    Food    and    Water.      Wm. 

G.  Savage,  B.Sc,  M.D.,  D.P.H.,   1911 

BOOKS   AND   PHOTOGRAPHS   PRESENTED    SINCE 

JANUARY    1914. 

Revue  Suisse  de  Zoologie  a  propos  de  Rotiferes.     Vol.  XXII. 
No.  1.     January  1914.     E.  Penard. 

Presented  by  the  Author. 

Sylloge    Algarum    Omnium.      Vol.    II.      Sect.    I.    Raphideae. 
J.  Bapt.  De  Toni. 
Presented  by  the  Author. 

My  Sayings  and  Doings.     Rev.  Win.  Quekett. 
Presented  by  G.  W.  Watt. 

Cothurindes  Muscicoles.     E.  Penard. 
Presented  by  the  Author. 

Sur  quelques  Teulaculiferes  Muscicoles.     E.  Penard. 
Un  curieux  Infusoire,  Lbgendrea  bellerophon.     E.  Penard. 

Presented  by  the  A  uthor. 

Eighty  Photographs   of  Drawings   of   Rotifera.      By  F.  R. 
Dixon -Nuttall. 
Presented  by  F.  R.  Dixon-Nuttall. 

Eighty  Photographs  of  Rotifera. 
Presented  by  J.  B.  Groom. 

Royal  Society  of  Victoria  :   Further  Notes  on  Australian 
Hydroids.     Part  II.     W.  M.  Bale,  F.R.M.S. 

Presented  by  the  Author. 


400  THE    LIBRARY. 

<  )donaten-Studien.     C.  Weseriberg-Lund. 
Presented  by  the  Author. 

WOHNUNGEN     UND     GEHAUSEBAU     DER     StJSSWASSERINSEKTEN.        C. 

Wesenberg-  Lund. 
Presented  by  the  Author. 

FoRTPFLANZUNGSVERHALTNISSE       PAARUNG       UND       ElABLAGE       DER 

Susswasserinsekten.     C.   Wesenberg-Lund. 
Presented  by  the  Author. 

Commonwealth  of  Australia,  Department  of  Trade  and 
Customs  :  Fisheries.  Biological  Results  of  Fishing  Ex- 
periments carried  on  by  T.I.S.  Endeavour.      1909-14. 

Report  on  the  Hydroida  Collected  in  the  Great  Australian 
Bight  and  other  Localities.     W.  M.  Bale,  F.R.M.S. 

Presented  by  the  Author. 

The  Journal  of  Micrology.     Parts  I. -IV. 
Presented  by  H.  Edwards. 

For  Sale — 50  copies — reprints  of  Paper  "  Lagenae  of  the 
South- West  Pacific  Ocean,"  by  Henry  Sidebottom.  Two  Parts. 
Price  2s.  Gd.     Application  should  be  made  to  the  Librarian. 


401 


THE    CLUB    CABINET. 

The  following  Slides  have  been    added   to  the  Cabinet  since 
October  1912  : 

Protozoa. 

Presented  by  G.  T.  Harris. 
K.A.  106.  Actinosphaerium  Eichomi  (binary  fission). 

Infusoria. 

Presented  by  J.  C.  Kaufmann. 
K.A.   102.  Euglena  sp. 

Presented  by  J.  Burton. 
107.  Euglena  viridis. 

Presented  by  G.  T.  Harris. 

103.  Ephelota  sp.  (stained  to  show  nucleus). 

104.  Ephelota  sp. 

105.  Noctiluca  miliar  is. 

Hydrozoa. 
Presented  by  G.  T.  Harris. 

(s  =  stained.) 

M.A.       4:.  Aglaophenia  pluma,  s. 

50.  Aglaophenia  pluma  (gonophores). 

51.  Bougainvillia,  muscus. 
14.   Cah/cella  syringa. 

23.  C ampamdaria  Jlexuosa,  s. 

52 .  C ampamdaria  flexuosa. 

53.  C ampamdaria  neglecta. 

54.  Clara  carnea. 


402  TJ1E    CLUB    CABINET. 

M.A.     55.  Clava  carnea,  s. 

56.  Clava  midticornis,  s. 

57.  Clava  squamata,  s 
17.  Clytia  Johnstoni,  s. 

58.  Clytia  Johnstoni. 

91.  Clytia  Johnstoni  (medusa). 
19.  Cordylophora  lacustris,  s. 

59.  Cordylophora  lacustris  (with  compound  bud),  s. 
8.  Coryne  pus  ilia,  s. 

60.  Coryne  vaginata  (gonophores),  s. 

61.  Coryne    vaginata  [with    epiphytal    Licmophora  /label  - 

lata). 

62.  Coryne  vaginata,  s. 

63.  Eudendrium  insigne, 

64.  Eudendrium  insigne  [with  Ephelota  :  Infusorian). 

65.  Gonothyrea  Loveni. 

66.  Halecium  Bcanii. 

67.  Hydra  fusca. 

68.  Hydra  viridis  (ovary  and  testes),  s. 

69.  Hydra  vulgaris,  s. 

92.  Lizzia  Blondini  (medusa). 

93.  Lucernaria  fascicularis  (medusa). 

70.  Obelia  dichotoma,  s. 

71.  Obelia  dichotoma. 

72.  Obelia  geniculata,  s. 

73.  Obelia  geniculata. 

74.  Perigonimus  sessilis. 

75.  Plumularia  echinulata. 

76.  Plumularia  echinulata. 

77.  Plumularia  echinulata,  s. 

78.  Plumularia  echinulata,  s. 

79.  Plumularia  halecoides,  s. 

80.  Plamidaria  halecoides. 

81.  Plumidaria  pinnata. 

82.  Plumularia  setacea. 

83.  Plumidaria  setacea. 

84.  Plumularia  setacea  (metatophores). 

85.  Plumularia  siinilis,  s. 

86.  Plumularia  similis. 

87.  Podocoryne  areolata,  s. 


THE    CLUB    CABINET.  403 

M.A.     28.   Sertularia  frfiada. 

88.  Sertularia  pumila,  s. 

89.  Sertularia  pumila. 

90.  Serti'liiri'i  pwmila. 

Echinodermata. 
Presented  by  J.  Burton. 
N.     19.  Plates  of  Taeniogyrus  A  llani. 

Rotifera. 
Presented  by  J.  C.  Kaufmann. 

Rot.   246.   Lacinularia  elliptica. 

Turbellaria. 

Presented  by  H.  Whitehead. 

Series  20  :  v:ith  descriptive  notes  and  diagrams. 

Jficrostomum  lineare. 

Phaenocora  (Derostomum)  punctatum. 

Daly  el  Ha  viridis. 

Daly  ell  ia  diadema. 

Gyratrix  herm  aphrodit  us. 

Dendrocoelum  lacteum. 

Planaria  alpina. 

Planar  ia  alpina  :  tr.  and  long.  sees. 

Planaria  gonocephala. 

Polyeelis  nigra. 

Poly celis  nigra  :  tr.  sec. 

Polyeelis  cornuta. 

V B.     35.  Tr.  sec.  (serial)  of  a  Planarian. 

Insecta. 

Presented  by  T.  A.  O'Doxohoe. 

R.  402.  Scales  of  Templetonia  crystallina. 
403.   Scales  of  Seira  Buskii. 

Presented  by  F.  H.  jST.  C.  Kemp. 
399.   Xaucoris  cimicoides  (adult). 


404  THE    CLUB    CABINET. 

Polyzoa. 

Presented  by  G.  T.  Harris. 

M.B.     33.  Aetea  anguina. 

84.  Bowerbankia  imbricata. 

85.  Pedicellina  cernaa. 

80.   Pedicellina  cemua,  var.  gracilis. 

Physiological  Histology. 

Purchased.     (With  descriptive,  illustrated  text.) 

Series  10.     The  Shin. 

Human  scalp,  with  hair  :  long,  and  tr.  sees. 

Human  scalp,  with  hair  :  long,  sec,  injected. 

Human  skin,  with  perspiration  glands  :  long.  sec. 

Human  skin,  stages  of  development  of  perspiration  glands  :  long. 

sec. 
Human  skin,  with  blood  vessels  injected  :  long.  sec. 
Skin  of  Dog,  with  elastic  fibres  :  long.  sec. 
Tactile  hairs  of  Ox,  with  blood  sinus  :  tr.  sec. 
Human  hair,  stages  of  development  :   long.  sec. 
Human  nail  :  lon^.  sec. 


*&■ 


Series  11.     Muscle,  bone,  etc. 

Human  embryo,  finger  and  arm  :  long.  sees. 

Muscle  of  Ring  Snake,  with  motor  nerve  plates. 

Muscle  of  Dog  :  tr.  sec.  and  long,  sec,  injected. 

Tendon  of  Ox  :  tr.  sec. 

Cervical  ligament  of  Ox  :  sec. 

Bone  of  Ox  :  long,  sec 

Cranial  bone  of  Dog  :  sec. 

Joint  of  Rabbit :  median  sec.  , 

Series  12.      Central  nervous  system. 

Spinal  cord  and  ganglion  of  Cat  :  tr.  sec. 

Spinal  cord  of  Cat  (Golgi  preparation  :  cell  impregnation). 

Spinal  cord  of  Dog  :  tr.  sec. 

Cerebral  cortex  of  Cat  (Golgi  preparation  :  cell  impregnation). 


THE    CLUB    CABINET.  405 

Cerebellum  of  Cat  (fibre  impregnation). 
Cerebrum  of  Man  (fibre  impregnation). 
Pineal  gland  of  Ox  :  tr.  sec. 
Pituitary  gland  of  Ox  :  tr.  sec. 
Embryonic  spinal  cord  of  Fowl. 
Embryo  of  Rabbit  :  tr.  sec. 

Series  13.     Reproductive  organs. 

Penis  of  Bull  :  tr.  sec. 
Glandula  vesicularis  of  Bull  :  sec. 
Spermatozoa  of  Bull. 
Testis  of  Mouse  :  tr.  sec. 
Umbilical  cord  of  Child  :  tr.  sec. 
Gravid  uterus  of  Pig  :  tr.  sec. 
Oviduct  and  ovary  of  Dog  :  tr.  sees. 
Ovary  of  new-born  Kitten  :  tr.  sec. 
Mammary  gland  of  Cow  :  tr.  sec. 

Series  14.      Respiratory  and  urinary  organs. 

Lung  of  Cat  :  injected. 

Lung  of  Cat  (elastic  fibres). 

Lung  of  Dog  (cell  pigmentation). 

Trachea  of  Cat  :  tr.  sec. 

Kidney  of  Rabbit :  injected. 

Kidney  of  Mouse  :  tr.  sec. 

Bladder  of  Ox  :  tr.  sec. 

Supra-renal  capsule  of  Ox  :   tr.  sec. 

Embryonic  okenian  body  of  Pig  :   tr.  sec. 

Thyroid  gland  of  Man. 

Series  15.      Tic  Eye. 

Cornea  of  Ox  (gold  impregnation). 

Choroid  of  Ox,  showing  pigment  cells. 

Retina  of  Ox. 

Optic  nerve  of  Ox  :  med.  sec. 

Eyelid  of  Calf  :  med.  sec. 

Lachrymal  gland  of  Ox. 

Glands  of  nictitating  membrane  of  Rabbit. 


406  THE    CLUB    CABINET. 

Anterior  half  eye  of  Ox,  without  lens  :  hor.  sec. 
Eye  of  embryo  Chick  :  med.  sec. 
Eye  of  embryo  Pig  :  med.  sec. 

Series  16.      Organs  of  hearing,  smell  and  touch. 

Auditory  organ  of  Cat  (sensory  hairs  of  ampullae). 

Auditory  organ  of  Cat,  membrana  tympani :   tr.  sec. 

Auditory  vesicle  of  embryo  Rabbit  :   long.  sec. 

Cochlea  of  Guinea  Pig  :  med.  sec. 

Nasal  mucous  membrane  of  Cat  :  tr.  sec. 

Nasal  mucous  membrane  of  Rabbit,  respiratory  portion. 

Olfactory  mucous  membrane  of  Rabbit :  tr.  sec. 

Circum vallate  papillae  of  Ox  :  mecl.  sec. 

Papilla  f oliata  of  Rabbit  :  tr.  sec. 

Pacinian  corpuscles  in  human  skin. 

Series  17.      Circulatory  and  blood-forming  organs. 

Renal  artery  and  vein  of  Pig  :  tr.  sec.  (fibres  stained). 

Renal  artery  and  vein  of  Pig  :  tr.  sec.  (cells  stained). 

Human  muscle  of  heart  :  tr.  sec. 

Embryo  of  Rabbit  :  tr.  sec.  in  region  of  heart. 

Human  blood  :  film  preparation. 

Human  blood  :  haemin  crystals. 

Red  bone  marrow  of  Pig. 

Human  spleen  :  sec. 

Human  thymus  gland  (child) :  sec. 

Lymphatic  gland  of  Pig  :  sec. 

Presented  by  C.   L.   Curties. 

(Slides  remounted  by  the  late  Sir  Benjamin  Ward  Richardson 

over  50  years  ago.) 

X.  428.   Medulla  of  Cat  :   tr.  sec,  injected. 

429.  Tongue  of  Rat  :  tr.  sec,  injected. 

430.  Duodenum  of  Turtle  :  tr.  sec. 

431.  Intestine  of  Guinea  Pig  :  vert,  sec,  injected. 

432.  Jejunum  of  Cat :  vert,  sec,  injected. 

433.  Large  intestine  of  Pig  :  tr.  sec,  injected. 

434.  Retina  of  Rat  :  injected. 

435.  Toe  of  Mouse  :  long,  sec,  injected. 


THE    CLUB    CABINET.  407 

X.   436.  Human  tooth  :  tr.  sec. 

437.  Human  large  intestine  :  vert,  sec,  injected. 

438.  Human  jejunum  :  vert,  sec,  injected. 
440.  Human  sole  of  foot  :  vert.  sec. 

Freshwater  Algae. 
Presented  by  J.  Burton. 

B.    112.   Anabaena  circinalis. 

122.  Apiocystis  Brauniana. 

119.  Batrachospermum  moniliforme. 

114.  Bulbochaete  sp. 

117.  Chaetophora  incrassata. 
116.   Choaspis  stictica. 

(Chrobcoccics  turgid  us. 
'  {0 oelosphaerium  Kuetzingianum. 

115.  Cladophora  flavescens. 

127.  Cladophora  sp.  (Lake  Zurich). 
B.   121.  Clathrocystis  aeruginosa. 

123.  Coleochaete  scutata. 
125.  Cosmarium  nitidulum. 

( Cylindrospermum  stagnate. 
'  {Lyngbya  sp. 
125.  Jlerismopedia  sp. 
41.  Micrasterias  rotata. 

128.  Oscillator ia  princeps. 
113.  Pandorina  morum. 

129.  Sphaeroplea  annulina. 

118.  Spirogyra  sp. 

120.  Tolypothrix  la/iata. 

130.  Trichodesmium  Ehrenbergi  (Atlantic  Ocean). 
53.  Zygnema  sp. 

Presented  by  Exor.  of  J.  M.  Allen. 
B.    111.  Ballia pulchrinum. 

Diatomaceae. 

Presented  by  S.  E.  Akehurst. 
A.  690.  Amphipleura  pellucida  (realgar). 


408  THE    CLUB    CABINET. 

Presented  by  J.  Burton. 

A.   688.  Rhipodophora  meneghiniana,  on  Ectocarpus. 
689.  Achnanthes  sp.,  conjugating  on  Marine  Algae. 

Purchased  :  mounted  in  styrax. 

A .  691.  A ctin ocyclus  pruinosus. 

692.  Actinoptychus  Bismarckii. 

693.  Actinoptychus  Grunowii. 

694.  Actinoptychus  hexagonus. 

695.  Actinoptychus  maculatus. 

696.  Amphora  Grevillei. 

697.  Asterolampra  aemulans. 

698.  Auliscus  mirabilis. 

699.  A  uliscus  permagna. 

701.  Biddulphia  Roperiana  (showing  mode  of  growth). 

702.  Biddulphia  Tuomeyi. 

700.  Brebissonia  Weissjlogii. 

703.  Campylodiscus  stellatus. 

704.  Clyphodesmis  Challenger ensis. 

705.  Cocconeis  extravagans. 

706.  Diploneis  exemeta. 

707.  Kntogonia  Daveyani. 

708.  Gymatopleura  solea. 

709.  Hantzschia  marina. 

710.  Mastogloia  cruciata. 

712.  Navicula  carinifera. 

711.  Navicula  follis. 

713.  Navicula  gemmulatula. 

714.  Navicula  irrorata. 

715.  Navicula  luxuriosa. 

716.  Navicida  notabilis. 

717.  Nitzschia  scalaris. 

718.  Omphalopsis  australis. 

719.  Opephora  Schivartzii. 

720.  Pinnularia  dactylis. 

721.  Plagiogramma  validum. 
252.  Pleurosigma  balticum. 

722.  Podocyrtis  adriaticus. 

723.  Raphoneis  (uujjhi.ceros. 


THE    CLUB    CABINET.  40!) 

A.  724.  Stephanopyxis  Campeachiana. 
725.  Stictodiscus  Nova- Zealand  ic  us. 
72G.  Stictodiscus  par ellel us,  var.  gibbosa. 

727.  Surirella  lata,  var.  robusta. 

728.  Surirella  Macraeana. 

729.  Terpsinoe  americana. 

730.  Triceratum  dejinitum. 

731.  Triceratum  favus,  var.  quadrata. 

732.  Triceratum  favus,  var.  maxima. 

733.  Triceratum  fractum. 

734.  Triceratum  grande. 

735.  Triceratum  Nova-Zealandicus. 

736.  Triceratum  Robertsianum. 

Fungi. 

Presented  by  J.  Burton. 

C.    190.  Sphoeria  herbarum. 
191.  Sphoerella  rusci. 

Bacteria. 
Presented  by  J.  Burton. 
0.   140.   Cohnia  roseo-persiciaa. 

Plant  Structure. 
Presented  by  C.  J.  H.  Sidwell. 

E.     38.  Leaf  of  Hydrocharis  morsus-ranae\  ri  tl   n 

q~t     *    *™    j         ,-      •     ••  -Cellular  structure, 

of.    Leai  oi  lradescantia  virginica        J 

E.A.     55.  Leaf  of  Croton  zambesicus 

58.   Leaf  of  Cynoglossum  micranthum 

52.  Leaf  of  Onosma  alboroseum 
57.  Leaf  of  Onosma  stellulatum 

53.  Leaf  of  Onosmodium  carolinianum 
24.  Leaf  of  Rhododendron  Dalhousia 
56.  Leaf  of  Rhododendron  Maddeni 
51.   leaf  of  Trirhodpsma  indicum 

54.  Leaf  of  Trichodesma  khasiana 


Hairs  and 
glands. 


410  THE    CLUB    CABINET. 

Seeds. 

Presented  by  C.  J.  H.  Sidwell, 

G.     43.  Anagallis  arvensis. 

41.  Castilleja  sp. 

46.  Castilleja  Cidbertsoni. 

43.  Cerastium  glomeratum. 

39.  Delphinium  niacrocentron. 

47.  Linaria  vulgaris. 

42.  Mohavea  viscida. 

45.  Pedicular  is  Frederica-Augusti. 

44.  Picrorhiza  Kurrooa. 

40.  Tricholoena  rosea. 


ill 


PROCEEDINGS 

OP    THE 

QUEKETT   MICROSCOPICAL   CLUB. 

At  the  497th  ordinary  meeting  of  the  Club,  held  on  March  24th, 
1914,  the  President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair, 
the  minutes  of  the  meeting  held  on  February  24th  were  read  and 
confirmed. 

Messrs.  C.  W.  Engelhardt,  Harry  Albert  St.  George,  E. 
Hermann  Anthes,  Felix  R.  W.  Brand,  Victor  M.  E.  Koch, 
Francis  W.  Lloyd,  Leonard  R.  Gingell  and  His  Excellency 
Nicholas  Yermoloff,  K.C.Y.O.,  were  balloted  for  and  duly  elected 
members  of  the  Club. 

* 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks  of 
the  members  voted  to  the  donors. 

The  President  said  :  "  My  attention  has  been  called  to  the 
fact  that  Mr.  Powell,  one  of  our  oldest  and  best-known  members, 
is  present  this  evening.  I  am  also  informed  that  Mr.  Powell 
celebrated  his  eightieth  birthday  on  Saturday  last.  May  I  be 
allowed,  on  behalf  of  the  Club,  to  offer  him  our  sincere  con- 
gratulations on  this  occasion,  and  to  express  our  satisfaction  that 
he  is  still  able  to  be  present  at  our  meetings  ? " 

Mr.  J.  W.  Ogilvy  (Messrs.  Leitz)  exhibited  an  illuminator  for 
opaque  objects  which  consists  of  a  bull's-eye  and  a  stage-condenser 
fitted  to  a  bar  which  is  carried  on  a  stand  having  universal 
movements.  Being  in  one  piece,  time  is  saved  in  setting  up  the 
apparatus. 

Mr.  N.  E.  Brown,  A.L.S.,  read  "  Some  Notes  on  the  Structure 
of  Diatoms." 

An  animated  discussion  followed  the  paper,  in  which  the 
President  and  Messrs.  O'Donohoe  and  Ainslie  took  part,  and  to 
which  Mr.  Brown  replied. 

A  hearty  vote  of  thanks  was  given  to  Mr.  Brown  for  his 
interesting  paper. 

The  Hon.  Sec.  read  a  paper,  communicated  by  Mr.  E.  M. 
Nelson,  F.R.M.S.,  on  "  A  New  Object-glass  by  Zeiss,  and  a  New 
Method  of  Illumination." 

Journ  Q.  M.  C,  Series  II.— No.  75.  29 


412  PROCEEDINGS    OF    THE 

Messrs.  Zeiss  exhibited  the  new  oil-immersion  l/7th  on  four 
microscopes,  and  the  thanks  of  the  meeting  were  accorded  to 
Messrs.  Zeiss  and  to  M.  Koch,  who  represented  the  firm. 


At  the  498th  ordinary  meeting  of  the  Club,  held  on  April  28th, 
1914,  the  Vice-President,  Mr.  D.  J.  Scourfield,  F.Z.S.,F.R.M.S., 
in  the  chair,  the  minutes  of  the  meeting  held  on  March  24th 
were  read  and  confirmed. 

Messrs.  Edward  Carlile,  Francis  Cooley-Martin,  Gerald  Burton 
Burton-Brown,  M.D.,  Francis  Edward  Robotham  and  Daniel 
Arthur  Davies,  jun.,  were  balloted  for  and  duly  elected  members 
of  the  Club. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks  of 
the  members  voted  to  the  donors. 

The  Hon.  Sec.  read  a  note  on  "  A  New  Low-power  Con- 
denser," communicated  by  Mr.  E.  M.  Nelson,  F.B..M.S. 

Mr.  C.  Lees  Curties  (Messrs.  C.  Baker)  exhibited  both  the 
low -power  condenser  designed  by  Mr.  Nelson  and  also  a  simple 
centring-stop  holder  which  he  had  suggested. 

Replying  to  a  question,  Mr.  C.  Lees  Curties  said  that  the 
aperture  of  the  condenser  was  0*55.  On  account  of  its  long 
working  distance,  the  condenser  would  be  particularly  useful  for 
dark-ground  illumination  when  examining  pond-life  in  a 
trough. 

Mr.  M.  A.  Ainslie  said  that  the  Leitz  achromatic  condenser 
with  the  top  off  had  an  aperture  of  0'6,  and  a  working  distance  of 
one-third  of  an  inch.  He  would  suggest  that,  when  necessary, 
the  condenser  should  be  decentred,  in  order  to  centre  the  stop. 
He  frequently  did  this  with  low  powers,  when  necessary. 

Votes  of  thanks  to  Mr.  Nelson  and  to  Mr.  Curties  were  pro- 
posed and  carried  unanimously. 

Mr.  N.  E.  Brown,  A.L.S.,  gave  an  account — illustrated  with 
fresh  specimens  of  the  flower  and  a  coloured  drawing  of  a  longi- 
tudinal section — of  "  The  Fertilisation  of  Vinca  minor"  He 
said  that  a  very  interesting  microscopic  object  was  concealed  in 
this  flower.  As  regards  its  fertilisation,  a  special  interest  was 
connected  with  the  flower  of  the  periwinkle.  The  fruit  of  this 
plant  is  extremely  rare,  not  only  in  this  country,  but  also  on  the 
Continent.     The  flower   has  a.  very  remarkable  structure,  and  a 


QUEKETT    MICROSCOPICAL    CLUB.  413 

section  exhibiting  the  stigma  has  several  points  of  interest.     At 
the  bottom  of  the  tube  are  two  large  glands  which  secrete  honey, 
one  on  each  side  of  the  ovary.     The  ovary  has  two  carpels,  which 
are  separate,  but  are  united  at  the  top  into  a  single  style.     This 
goes  up,  and  at  the  top  expands  into  a  wing-like  disc,  and  termi- 
nates with  a  crown  of  hairs  like  a  sweep's  brush.      Some  of  these 
hairs  turn  down  into  five  little  tufts,  forming  little  alcoves,  which 
play    very    important    functions.      From    the    corolla    arise   five 
stamens.    The  anthers  are  raised  above,  and  are  so  curved  over  as 
to  enclose  the  whole  and  prevent  ingress  except  between  each  pair 
of  stamens.     The  anthers  open  while  in  the  bud,  and  then  shed 
their  pollen,  which,  when  the  flower  opens,  is  seen  to  be  deposited 
in  five  little  heaps.      Underneath  the  wheel-like  formation,  often 
spoken  of  as  a  stigma,  we  find  a  frill-like,  orange-coloured  body, 
which  is  not  of  the  same  depth  all  round,  but  opposite  the  little 
alcoves  already  referred  to  deepens  slightly.     The  true  stigma  is 
formed  by  this  curtain,  or  frill,  and  there  we  find  the  true  stig- 
matic  tissue.     Now  as  regards  fertilisation.     Insects  (bees)  come 
for  the  nectar  situated  at  the  base.     Grooves  guide  the  tongue 
between  two  anthers  and   past  the  upper  ledge  of  the  shelf,  or 
frill.    Here  it  passes  the  little  masses  of  pollen,  which  are  slightly 
glutinous,  and,  before  reaching  the  honey-glands,  comes  in  contact 
with  a  wet,  viscid  fluid.     ^Yhell  the  tongue  is  withdrawn,  the 
smeared  surface  comes  in  contact  with  the  mass  of  pollen,  which 
adheres  to  it.     But  the  plant  does  not  want  to  part  with  all  its 
masses  of  pollen,  and  so  some  is  scraped  off  the  proboscis  by  the 
projecting  hairs,   and  remains  until  the   visit    of   another  bee, 
which,   perhaps,   has   already  visited   a  periwinkle  flower.     The 
tongue  passes  down  past  the  stigmatic  frill ;  but  in  coming  back 
scrapes  the  pollen  off  on    the   under   side,   no    trace  of  pollen 
remaining  on  the  part  of  the  tongue  previously  smeared  with 
the  viscid  matter.     This  is  the  manner  in  which   the  plant  is 
fertilised.     Last  year  the  speaker  had  examined  many  plants  in 
order  to  see  if  they  had  been  fertilised.     It  is  commonly  stated 
that  V.  minor  is  infertile  to  its  own  pollen,  and  so  seeds  are  rare. 
Nearly  all  plants  in  one  locality  are  probably  products  of  one 
plant,  and  have  not  come  from  seed.     Of  the  plants  examined, 
70  per  cent,  had  been  fertilised  by  insects  ;  but  no  fruit  of  any 
kind  developed  on  the  clump  under  observation.     Mr.  Brown  this 
year  had  fertilised  one  hundred  flowers ;  but  it  is  yet  too  early  to 


414  PROCEEDINGS    OF    THE 

be  able  to  report  any  results.  This  year  was  noticeable  for  a 
great  dearth  of  pollen,  all  the  anthers  being  more  or  less  barren. 
He  awaited  with  interest  the  result  of  his  artificial  pollination. 

The  Chairman  said  that  at  first  thought  it  might  possibly  be  a 
case  of  over -elaboration. 

Mr.  R.  Paulson  asked  if  Mr.  Brown  had  cut  sections  to  see  if 
any  of  the  pollen  grains  had  thrown  out  tubes.  He  preferred  to 
distinguish  between  the  terms  "  pollination  "  and  "  fertilisation." 
As  is  well  known,  there  are  some  plants  in  the  British  flora 
where  pollination  does  take  place,  but  which  are  infertile.  As 
an  instance  he  would  mention  the  lesser  celandine  Ranunculus 
fizaria.  Had  Mr.  Brown  ever  seen  any  seeds  of  this  plant  1  It 
might  be  imagined  that  its  seeds  would  be  very  numerous  ;  but 
this  is  not  the  case.  It  does  seem  that  in  many  plants  we  have 
instances  of  over-elaboration.  He  would  instance  orchids  and 
violets — and  especially  with  regard  to  violets.  Violets  produce 
abundant  seed,  not  by  the  attractive  flowers,  but  by  little  green 
flowers  which  are  usually  missed  by  the  ordinary  observer. 
These  little  green  flowers  never  open  and  the  anthers  shed  their 
pollen  directly  on  to  the  stigmas. 

Mr.  0.  E.  Heath  asked  whether  the  pollen  of  Vinca  minor  had 
been  seen  to  form  tubes. 

The  Hon.  Secretary  suggested  that  the  pollen  might  be  tested 
practically,  under  the  microscope,  in  a  weak  solution  of  sugar- 
and-water.  If  the  grains  did  put  out  tubes,  he  thought  it  would 
prove  the  possibility  of  fertilisation. 

Mr.  Brown,  replying,  said  that  even  if  the  pollen  grains  pro- 
duced tubes  in  a  sugar-and-water  solution,  it  would  be  no 
guarantee  that  they  would  also  do  so  in  the  flower.  He  intended, 
however,  to  examine  the  pollen  and  also  to  cut  sections. 
Regarding  the  celandine,  in  the  South  of  England  it  seeds  quite 
freely.  It  is  possibly  a  question  of  temperature.  Not  all  violas 
have  cleistogamous  flowers  ;  some  usually  produce  seed  from  the 
ordinary  open  flowers. 

The  Hon.  Secretary  (Mr.  James  Burton)  read  a  note  on  "An 
Abnormal  Form  of  Arachnoidiscas  ornatus."  He  wished  to  draw 
attention  to  the  plate  of  Arachnoidiscus,  by  Beck,  in  Carpenter's 
The  Microscope  and  its  Revelations,  a  copy  of  which  was  on  the 
table.  The  drawing  represented  the  diatoms  entire  and  still 
attached  to  the  seaweed  on  which  they  occurred.     It  showed  their 


QUEKETT    MICROSCOPICAL    CLUB.  415 

living  form.     That  which  we  are  accustomed  to  find  on  mounted 
slides  is  only  a  part  of  the  organism.     He  was  exhibiting,  under  a 
microscope,  a  slide  given  him   by  Mr.  Williams,  of  Folkestone, 
which  displayed  very  beautifully  the  box-like  form  of  this  diatom. 
It  consists  of  a  top  and  a  bottom  circular  plate,  known  as  valves, 
to  each  of  which  is  attached  a  ring,  called  by  some  authors  the 
girdle ;  that  of  the  top — or  lid,  as  it  might  be   called — fitting 
outside  that  of  the  lower,  or  box -like,  part.     The  whole  closely 
resembles    an  ordinary  circular    "  chip '!   specimen-box.     On    the 
slide  exhibited,  examples  of  an  abnormal  form  occur,  in  which 
the  bottom  of  the  box  has  the  "girdle"   greatly  elongated,  the 
"lid"  still  remaining  shallow,  as  in  a  normal  form.     This  struc- 
ture gives  the  diatom,  when  viewed  sideways,  the  appearance  of  a 
cylinder,  instead  of  that  of  a  disc  with  but  slight  depth,  and  when 
observed  under  a  binocular  with  dark-ground    illumination  the 
difference  is  very  striking.     The  girdle  is  marked  by  circles  of 
lines  running  round,  as  though  it  were  composed  of  superimposed 
rings.     On    the    rings    are    small    projections    or    points.     The 
frustules    are   empty,   and   there   is   no   appearance  of   the   com- 
mencement of  dividing-walls  inside,  which  might  have  indicated 
that  the  unusual  form  was  owing  to  the  beginning  of  the  process 
of  subdivision.     In  a  normal  form  the  depth  was  30  /x ;  in  a  case 
where  subdivision  was  far  advanced  the  depth  was  54 /x.     In  an 
abnormal  specimen  the  depth  was  96 /x;  another  was  105  /x.     The 
diameter  in  all  the   forms  measured  is  fairly   constant,  varying 
from  105  /x  to  114  /x.     The  abnormal  form  is  only  known  to  occur 
in  one  collection  of  material  from    Mauritius,  and    in  that  the 
percentage  is  very  small.     No  explanation  or  suggested  cause  of 
the  unusual  form  was  forthcoming. 

Mr.  Burton  was  complimented  on  the  opportunity  of  bringing 
this  interesting  slide  under  the  notice  of  members. 

Several  members  had  interesting  exhibits  under  microscopes, 
Mr.  G.  K.  Dunstall  showing  Flosadaria  cyclops,  which  is  worthy 
of  being  recorded. 


At  the  499th  ordinary  meeting  of  the  Club,  held  on  May  26th, 
1914,  the  President,  Prof.  A.  Dendy,  D.Sc,  F.R.S.,  in  the  chair, 
the  minutes  of  the  meeting  held  on  April  28th  were  read  and 
confirmed. 

Messrs.    Henry    Turing    Peter,  Sydney    G.  Bills   and  .Robert 


416  PROCEEDINGS    OF    THE 

William  Buttemer  were  balloted  for  and  duly  elected  members  of 
the  Club. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks  of 
the  members  voted  to  the  donors. 

Mr.  W.  R.  Traviss  exhibited  a  number  of  specimens  of  insects 
in  amber. 

Mr.  A.  E.  Hilton  read  "  Some  Notes  on  the  Cultivation  of 
Plasmodia  of  Badhamia  utricularis"  He  said  that  a  free- 
flowing  mass  of  naked  and  almost  undifferentiated  protoplasm, 
such  as  we  have  in  a  plasmodium  of  B.  utricularis,  suggests 
opportunities  for  biological  experiments  with  unusual  promise  of 
success. 

The  chief  purpose  of  this  paper,  Mr.  Hilton  said,  was  to  place 
on  record  the  results  of  experiments  made  during  the  last  few 
months,  which  suggest  a  method  of  continuous  cultivation  of 
plasmodia  of  B.  utricularis  at  once  simple  and  practicable. 

The  President  said  they  were  very  much  obliged  to  Mr.  Hilton 
for  his  very  interesting  and  practical  paper,  which  he  should  find 
of  great  value  to  himself,  as  he  had  hitherto  had  great  difficulty 
in  feeding  this  organism.  He  hoped  the  methods  described  would 
come  into  general  use  for  laboratory  work,  where  the  plasmodium 
was  very  useful  as  an  illustration.  He  should  like  to  ask 
Mr.  Hilton  if  he  had  tried  how  long  he  could  keep  the  plas- 
modium in  a  dry  state  on  the  blotting-paper.  Mr.  J.  J.  Lister 
at  Cambridge  used  to  feed  it  on  fungus,  but  this  was  sometimes 
difficult  to  get.  He  hoped  that  many  members  of  the  Club  would 
experiment  in  the  manner  suggested. 

Replying  to  several  questions,  Mr.  Hilton  said  the  dried 
sclerotium  is  capable  of  reviving  after  at  least  three  years;  but 
it  must  be  kept  dry,  and  never  allowed  to  become  damp.  After 
so  long  a  period,  it  might  take  four  or  five  days  to  recover.  He 
could  not  say  if  it  were  possible  to  cultivate  the  plasmodium  form 
from  sporangia.  A  difference  in  colour  has  been  noticed  in 
specimens  cultivated  on  plain  bread  compared  with  specimens 
fed  on  the  special  mixture.  The  former  are  a  lighter  yellow 
than  the  latter ;  but  various  shades  of  yellow  are  present  even  in 
one  plasmodium.  He  had  found  a  constant  temperature  of  about 
50°  F.  the  best. 

A  very  hearty  vote  of  thanks  was  accorded  to  Mr.  Hilton  for 
his  paper. 


QUEKETT    MICROSCOPICAL    CLUB.  417 

The  Hon.  Secretary  read  a  paper  on  "  Binocular  Microscopes," 
communicated  by  Mr.  E.  M.  Nelson,  F.R.M.S.  In  recent  years 
several  binoculars  have  been  introduced,  none  of  which,  however, 
can  be  called  new.  The  first,  the  Greenough,  by  Zeiss  (Journal 
R.M.S.,  1897,  pp.  599,  600),  was  a  twin  microscope — a  form  of 
binocular  invented  by  Pere  Cherubin  d'Orleans  nearly  three 
hundred  years  ago.  The  second — by  F.  E.  Ives,  in  1902  {Journal 
R.M.S.,  1903,  p.  85) — is  very  similar  to  one  designed  by  Wenham 
in  1866  as  a  counterblast  to  Powell's  high-power  binocular,  in 
which  the  whole  beam  is  sent  into  each  eye.  The  third,  a  modifi- 
cation of  the  second,  by  Leitz  {Journal  R.M.S.,  1914,  p.  5),  and 
the  fourth,  by  Beck,  which  is  very  similar  to  that  of  Ives. 

Mr.  Nelson  concluded  his  paper  by  some  remarks  on  the 
position  of  the  two  new  binoculars.  From  what  has  been  said, 
it  will  be  seen  that  they  are  a  class  by  themselves.  It  would  be 
quite  inaccurate  to  entertain  the  idea  that  these  instruments  are 
a  new  kind  of  stereoscopic  binocular  constructed  to  enter  into 
competition  with,  and  finally  to  supersede,  existing  binoculars  of 
the  Wenham  and  Stephenson  type,  for  they  only  possess  the  first 
attribute — stereoscopism — in  a  limited  manner.  Their  use  is 
confined  to  the  employment  of  full  Ramsden  discs  in  each  eye — 
that  is,  for  work  with  non-stereoscopic  images.  When  prolonged 
work  is  undertaken  with  one  of  the  new  binoculars,  great  relief 
and  comfort  to  the  eyes  will  be  secured. 

Messrs.  Beck,  represented  by  Mr.  C.  Beck  and  Mr.  Creese, 
exhibited  two  of  their  new  model  high-power  binoculars,  one 
giving  an  excellent  image  of  Pleurosigma  angulation  with  a  1/1 2th 
oil-immersion,  and  on  the  other  stand  a  lower  power  exhibited  to 
perfection,  first,  stereoscopic,  and,  second,  pseudo-stereoscopic 
vision  obtained  by  altering  the  tube-length.  Mr.  Creese  also 
exhibited  a  Wenham  binocular  with  a  l/6th  objective,  giving  a 
perfectly  evenly  illuminated  field  at  300  diameters  of  a  section  of 
the  eye  of  the  drone-fly. 

Messrs.  Leitz's  London  representative,  Mr.  J.  W.  Ogilvy, 
showed  seven  stands  of  their  new  model,  with  powers  ranging 
from  1/1 2th  oil-immersion  apochromat  and  1,500  diameters  to 
1  in.  and  x  35.  Two  Leitz-Greenough  models  with  low  powers 
were  also  exhibited.  The  preparations  shown  included  Amphi- 
pleura  pellucida,  Poclura  scale,  rock  sections,  and  histological 
preparations. 


418  PROCEEDINGS    OF    THE 

Mr.  Nelson  also  sent  for  exhibition  a  photograph  of  a  new 
slide,  designed  by  Mr.  G.  Nelson,  for  the  portable  Greenough,  to 
hold  three  pairs  of  objectives.  It  allows  the  powers  to  be  changed 
by  moving  the  slide  forward,  and,  in  brief,  is  for  the  Greenough 
what  a  rotating  nosepiece  is  for  an  ordinary  microscope. 


At  the  500th  ordinary  meeting  of  the  Club,  held  on  June  23rd, 
1914,  the  Vice-President,  Mr.  E.  J.  Spitta,  L.R.C.P.,  M.R.C.S., 
in  the  chair,  the  minutes  of  the  meeting  held  on  May  26th  were 
read  and  confirmed. 

Messrs.  Geoffrey  Norman,  Charles  James  Reeves  King,  William 
Henry  Scott,  Charles  Worthington  Hawksley,  Martin  Herbert 
Oldershaw  and  Edmund  John  Weston  were  balloted  for  and  duly 
elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read  and  the  thanks  of 
the  members  voted  to  the  donors. 

Mr.  Watson  Baker,  jun.,  read  a  short  paper  describing  a 
series  of  sections  of  fossils  from  the  Coal  Measures.  Many  of 
these  were  not  only  rare,  but  were  almost  unique  in  the  beautiful 
manner  in  which  they  showed  the  various  structures,  both  of 
plants  and  animals.  They  were  exhibited  under  a  number  of 
microscopes,  lent  and  arranged  for  the  occasion  by  Messrs. 
Watson  &  Son.  There  were  on  view,  also,  whole  specimens 
still  attached  to  the  rock  in  which  they  were  found.  Mr.  Watson 
Baker  said  the  specimens  had  been  sent  to  him  by  a  well-known 
authority  on  palaeo-botany,  and  as  many  of  them  were  of  unusual 
merit,  he  thought  the  Club  would  like  to  see  them.  He  then 
gave  an  interesting  description  in  some  detail :  a  condensed  account 
is  as  follows  :  No.  1.  A  specimen  of  the  lower  jaw  of  Elonicthys, 
with  teeth  in  situ.  No.  2.  Flank  scales  from  the  same.  Elonic- 
thys is  a  genus  of  fishes  having  a  bony  armour  or  a  skeleton. 
Devonian  and  Carboniferous,  they  existed  in  large  numbers  and 
great  variety,  some  attaining  a  great  size.  No.  3.  A  specimen  of 
the  Caeleanthidae  (hollow-spined  fishes),  which  range  from  the 
Upper  Devonian  to  the  Chalk.  Specimens  of  these  in  situ  were 
on  the  table.  Nos.  4  and  5  were  sections  of  teeth  of  species  of 
shark,  Diplodus  equilateralis  and  D.  gibbosus ;  also  an  uncut 
example  of  one  of  the  teeth.  Nos.  6  and  7.  Sections  of  coal  from 
Mossfield  Colliery,  Longton,  showing  various  vegetable  tissues. 


QUEKETT    MICROSCOPICAL    CLUB.  419 

Microspores  and  Megaspores — reproductive  organs  resembling 
those  of  modern  Lycopods  were  clearly  evident.  No.  8.  Plant 
remains  of  a  similar  character.  No.  9.  A  number  of  Fern 
sporangia,  showing  the  annulus,  etc.,  embedded  in  a  matrix  of 
fragmentary  plant  remains.  No.  10.  A  section  showing  the 
seeds  of  Cordaites  :  a  genus  of  fossil-plants  allied  to  some  of  the 
recent  Gymnosperms. 

The  chairman  remarked  on  the  very  beautiful  series  of  micro- 
scopical slides,  and  on  the  hand  specimens  on  the  table,  and  pro- 
posed a  vote  of  thanks  to  Mr.  Watson  Baker,  which  was  responded 
to  heartily. 

The  Hon.  Secretary  read  a  letter  from  Dr.  M.  C.  Cooke,  and 
extracts  from  others  received  from  Alphaeus  Smith,  Albert  D. 
Michael  and  G.  0.  Karrop,  who  were  unable  to  be  present,  con- 
gratulating the  Club  on  its  continued  prosperity,  and  wishing 
it  all  success  in  the  future.  These  were  received  with  much 
appreciation  by  the  meeting. 

The  chairman  then  gave  a  short  resume  of  the  history  of  the 
Club.  He  said  that  though  named  in  honour  of  the  celebrated 
Dr.  Quekett,  it  was  not  founded  by  him,  originating  four  or  five 
years  after  his  death.  It  was  considered  by  a  Mr.  Gibson  that 
an  association  of  amateur  microscopists  was  desirable,  and  he  put 
an  announcement  into  Hardwicke's  Science  Gossip  to  that  effect. 
The  idea  at  first  seemed  to  be  to  combine  music  and  microscopy 
at  the  evening  meetings.  The  suggestion  was  rapidly  and 
enthusiastically  taken  up,  and  in  July  1865  the  Club  was 
definitelv  started.  Soon  the  meetings  came  to  be  held  at 
University  College ;  but  it  is  curious  to  note  that  some  of  the 
preliminary  ones  were  held  in  Hanover  Square,  so  that,  again 
occupying  rooms  in  Hanover  Square,  the  Club  has  returned  to 
its  old  locality.  Among  the  very  earliest  members  Mr.  Lewis's 
name  appears.  He  was  elected  in  April  1866 — forty-eight  years 
ago,  and  has  held  the  position  of  honorary  reporter  from  the 
very  early  years  of  the  Club.  He  has  attended  485  out  of 
the  500  ordinary  meetings — almost  certainly  a  record — and 
several  of  the  omissions  occurred  only  this  last  winter,  owing 
to  illness  and  advancing  years.  Another  very  old  member  is 
Mr.  Alphaeus  Smith,  who  held  the  post  of  hon.  librarian 
for  forty  years,  and  is  still  a  member,  though  not  on  the  active 
list.     Dr.  M.  C.  Cooke,   Mr.  J.  Terry,   Mr.  T.   H.   Powell,  and 


420  PROCEEDINGS    OF    THE 

Mr.  Millett  all  joined  in  1865,  and  are  still  members.  Dr. 
Spitta  referred  to  the  work  of  Dr.  Karop  and  Mr.  Earland, 
both  of  whom  had  been  hon.  secretaries  in  former  years,  and  to 
whom  the  Club  was  greatly  indebted  for  its  success.  Lantern 
photographs  of  Dr.  Quekett  and  of  pages  of  the  old  attendance- 
books,  showing  names  of  original  members,  and  various  scenes 
connected  with  the  Club's  life,  were  thrown  on  the  screen. 
Dr.  Spitta  wound  up  his  interesting  and  delightfully  humorous 
discourse  by  recounting  a  supposed  reverie  (in  verse)  in  which  he 
saw  most  of  the  present  officers  and  prominent  members  coming 
into  a  meeting,  and  detailed  with  delicate  skill  and  good  nature 
their  hobbies  and  characteristics.  He  then  called  upon  some  of 
the  older  members—of  whom  a  satisfactory  number  had  been 
able  to  attend — to  say  a  few  words. 

Mr.  Lewis  made  a  little  speech,  in  which  he  disclaimed  the 
title  of  "veteran,"  as  he  said  Mr.  Powell  was  before  him,  and  he 
spoke  of  Mr.  A.  Smith,  who  joined  just  after  him.  He  was  able 
in  some  respects  to  supplement  the  chairman's  remarks  of  what 
took  place  at  the  earliest  meetings,  and  said  in  conclusion  that 
"  though  my  recent  illness  has  shaken  my  health,  and  I  shall 
have  to  give  up  many  things,  the  last  I  shall  give  up  will  be  the 
Quekett  Microscopical  Club,  from  which  I  have  derived  much 
information,  and  have  made  many  old  and  valued  friends,  and  no 
one  connected  with  the  Club  has  its  interests  more  at  heart  than 
myself."  His  remarks  were  received  with  enthusiasm  by  the 
members,  who  showed  their  appreciation  by  prolonged  cheers. 

Mr.  T.  H.  Powell  (forty-nine  years  a  member)  wound  up  what  he 
said  by  remarking  that  he  always  enjoyed  himself  at  the  pleasant 
meetings  of  the  Quekett.  Mr.  F.  Enock  addressed  the  meeting 
appropriately,  and  was  followed  by  Mr.  Earland,  who  made  an 
interesting  and  humorous  speech  on  some  of  his  experiences  as 
secretary.  He,  like  others,  referred  to  Mr.  Lewis,  and  rejoiced 
to  see  him  still  at  the  seat  at  the  reporter's  table  he  had  occupied 
so  long.  Again  the  audience  showed  their  appreciation  by  cheers. 
Mr.  Hilton  followed.  He  pointed  out  that  till  quite  recent 
years,  during  the  long  career  of  the  Club,  there  had  been  only 
two  librarians,  owing  to  Mr.  Smith's  long  tenure  of  the  office. 
He  also  remarked  on  the  large  attendance  at  the  meetings  now, 
saying  that  they  could  not  realise  what  it  was  to  have  a  meeting 
with  only  six  or  even  fewer  present ;  but  stated  that  there  was 


QUEKETT    MICROSCOPICAL    CLUB.  421 

no  less  good  will  and  friendliness  among  them  now,  and  desire 
to  help  and  welcome  new-comers.  He  felt  it  had  been  a  great 
advantage  to  himself  to  belong  to  the  Club. 

The  chairman  then  proposed  a  rhyming  "  toast,"  wishing 
"  Long  life  to  the  Club,"  and,  at  his  request,  the  members  rose  in 
a  body  and  "  made  the  welkin  ring  "  in  their  concurrence  with 
the  sentiment  he  had  so  deftly  expressed. 

To  wind  up  a  very  pleasant  evening,  Dr.  S  pitta  exhibited 
upon  the  screen  a  series  of  lantern  views  of  natural  objects, 
beautifully  nature-coloured.  Many  of  various  flowers  were 
wonderful  productions,  with  the  colours  unbelievably  soft  and 
lifelike,  and  some  of  the  insects  were  not  less  successful.  The 
meeting  then  broke  up,  many  staying,  however,  to  examine  more 
leisurely  Mr.  Watson  Baker's  unique  specimens. 

Unfortunately  too  late  to  be  read  at  the  meeting,  a  Marconi- 
gram  arrived  from  the  late  hon.  secretary,  Mr.  W.  B.  Stokes,  at 
Montreal  :  "  Congratulations  five  hundredth  meeting."  (Signed) 
Stokes. 


422 


OBITUARY   NOTICE. 

MORDECAI   CUBITT   COOKE,  M.A.,    LL.D.,   A.L.S. 

(Born  July  12th,  1825;  died  November  12th,  1914.) 

It  is  with  feelings  of  great  regret  we  have  to  record  the  death,  in 
his  ninetieth  year,  of  Dr.  M.  C.  Cooke,  the  "  Father  of  the  Club," 
which  took  place  on  November  12th  at  his  residence  in  Southsea. 

Dr.  Cooke  was  born  in  1825  at  the  village  of  Horning  in 
Norfolk,  where  his  parents  kept  a  general  shop.  From  an  early- 
age  he  was  dependent  upon  his  own  resources,  und  was  in  turn 
employed  as  draper's  assistant,  teacher  in  a  National  school  and 
lawyer's  clerk.  As  an  assistant  in  the  Indian  Museum  he  at 
last  found  congenial  occupation,  and  when  that  institution  was 
abolished  spent  some  time  at  the  South  Kensington  Museum,  in 
the  Mycological  Department.  He  afterwards  joined  the  Her- 
barium at  the  Royal  Botanic  Gardens,  Kew,  and  was  for  twelve 
years  (1880-92)  in  charge  of  the  Cryptogamic  Department ;  in 
the  latter  year  he  retired  on  a  pension. 

During  this  time  he  incorporated  his  own  herbarium,  con- 
taining 46,000  specimens,  with  the  existing  collection  at  Kew, 
as  well  as  the  collection  of  fungi  presented  to  Kew  by  the 
Rev.  M.  J.  Berkeley.  His  figures  of  fungi,  mostly  coloured  and 
numbering  25,000  plates,  are  also  at  Kew. 

His  first  important  work  was  the  Handbook  of  British  Fungi, 
in  two  volumes,  published  in  1871,  followed  by  Mycogra'phia,  or, 
coloured  figures  of  fungi  from  all  parts  of  the  world,  113  plates  ; 
Handbook  of  Australian  Fungi ;  and  Illustrations  of  British 
Fungi,  1,200  coloured  plates.  In  addition  to  the  above,  over 
300  articles  on  mycological  subjects  are  credited  to  Dr.  Cooke  by 
Lindau  and  Sydow  ;  for  a  period  of  fifteen  years  he  also  edited 
Grevillea,  a  journal  devoted  to  cryptogamic  botany. 

After  his  retirement  in  1892  Dr.  Cooke  retained  his  interest  in 
fungi,  and  until  1904  attended  the  annual  fungus  foray  of  the 
Essex  Field  Club.  Recently  his  eyesight  failed,  though  his  mind 
remained  keen  and  active.     He  was  honorary  M.A.  of  Yale,  and 


OBITUARY    NOTICE.  423 

LL.D.,  and  in  1903  he  had  the  honour  of  being  awarded  the 
gold  medal  of  the  Linnean  Society. 

In  addition  to  his  scientific  publications,  he  was  the  author 
and  editor  of  a  number  of  popular  books  in  Natural  History,  and 
was  at  the  time  associated  with  the  publisher  of  Hardwicke's 
Science  Gossip,  of  which  journal  he  was  editor  from  its  beginning 
in  1865  until  December  1871. 

In  the  Journal  of  the  Q.M.C.  for  November  1899  will  be  found 
"  Early  Memories  of  the  Q.M.C,"  a  short  paper  contributed  by 
Dr.  Cooke  on  the  early  history  of  the  Club.  Dr.  Cooke  was  one 
of  the  eleven  members  who  attended  the  preliminary  meeting 
held  on  June  14th,  1865,  and  the  meeting  on  July  7th,  when 
the  Q.M.C.  originated,  and  he  was  then  elected  one  of  its 
first  Vice-Presidents.  He  was  President  in  1882  and  1883, 
and  was  elected  an  honorary  member  in  1893.  He  was  always 
a  very  active  spirit  at  committees,  meetings  and  excursions  as 
long  as  he  attended ;  his  last  recorded  attendance  was  in  May 
1900. 

Many  of  us  will  recall  that  our  first  excursions  into  the  fairy- 
land of  science  were  made  under  the  guiding  hand  of  Dr.  M.  C. 
Cooke. 


424 


Table  for  the  Conversion  of  English  and  Metrical 
Linear  Measures;   Yard  and  Metre  at  same  Temperature. 


1  -i- 

2 

mm. 

1  + 

A4 

1  -r- 

fl 

1  + 

A« 

H 

A* 

12-70 

27 

940 

53 

479 

79 

321 

125 

203 

*> 

o 

8-4  6 

28 

907 

54 

470 

80 

317 

130 

195 

4 

6-35 

29 

876 

55 

462 

81 

313 

135 

188 

5 

5-08 

30 

846 

56 

453 

82 

310 

140 

181 

6 

4-23 

31 

819 

57 

445 

83 

306 

i  145 

175 

7 

3-63 

32 

794 

58 

438 

84 

802 

150 

169 

8 

3-17 

33 

76!) 

59 

430 

85 

299 

155 

164 

9 

2-82 

34 

747 

60 

423 

86 

295 

160 

159 

10 

2-54 

725 

61 

416 

87 

292 

165 

1 54 

11 

2-31 

3(5 

705 

62 

410 

88 

289 

170 

149 

12 

212 

37 

686 

63 

403 

S!) 

285 

175 

145 

13 

1-95 

38 

668 

64 

397 

90 

282' 

180 

141 

14 

1-81 

31) 

651 

65 

391 

91 

279 

185 

137 

15 

1-69 

40 

635 

66 

385 

92 

276 

190 

1 34 

16 

1-59 

41 

619 

67 

379 

93 

273 

195 

130 

17 

1-49 

42 

605 

68 

373 

94 

270 

200 

127 

18 

1-41 

43 

591 

69 

368 

95 

267 

205 

124 

19 

1-34 

44 

577 

70 

363 

96 

265 

210 

121 

20 

1-27 

45 

564 

71 

358 

97 

262 

215 

118 

21 

1-21 

-if ; 

552 

72 

353 

98 

259 

220 

115 

22 

115 

47 

540 

73 

348 

99 

256 

225 

113 

23 

1-10 

48 

529 

74 

343 

100 

254 

230 

110 

24 

1-06 

49 

518 

75 

339 

105 

242 

;  235 

108 

25 

1-02 

50 

508 

76 

334 

110 

231 

i  240 

106 

A4 

51 

498 

77 

330 

i  115 

221 

i  245 

104 

26 

977 

52 

488 

78 

326 

120 

212 

!  250 

102 

As  the  measurements  of  many  microscopical  objects  are  given  in 
fractions  of  an  inch  in  English  literature,  and  in  metrical  measure  in 
foreign  works,  the  above  table  has  been  drawn  up  to  facilitate  com- 
parison. Its  use  is  obvious.  Examples  :  l/7th  inch  =  3  63  mm.,  l/58th  inch 
=  438  ft,  or  -438  mm.  For  fractions  smaller  than  1 /250th  inch  that  portion 
of  the  table  between  the  figures  26  and  99  may  be  used  by  cutting  off 
the  last  figure  for  hundredths,  and  the  two  last  figures  for  thousandths. 
Examples:  1 /270th  inch  =  94*0  p,  or  -0940  mm.;  l/7900th  inch  =  321  p, 
or  "00321  mm.  When  that  portion  of  the  table  between  the  figures  100 
and  250  is  used  it  is  only  necessary  to  cut  off  the  last  figure  for  thousandths 
and  the  two  last  figures  for  ten  thousandths.  Examples :  l/1350th  inch 
=  18-8  p,  or  -0188  mm.,  l/16500th  inch  =  1-54  p,  or  -00154  ram.  The 
conversion  of  millimetres  into  fractions  of  an  inch  is  performed  in  the  same 
manner;  thus,  529  p  or  -529  mm.  =  l/48th  inch;  39-7  p  or  -0397  mm. 
=  l/640th  inch  ;  2-62  p  or  -00262  mm.  =  l/9700th  inch  ;  1-04  p  or  -00104 
mm.  =  l/21500th  inch;  -977  p  or  -000977  mm.  =  l/26000th  inch,  and 
so  on. — E.  M.  N. 


425 


THE  EARLY  HISTORY  OF  THE  QUEKETT  MICRO- 
SCOPICAL CLUB. 

By  R.  T.  Lewis,  F.RM.S. 

The  Quekett  Microscopical  Club  this  year  attains  its  Jubilee, 
and,  as  no  doubt  many  of  its  present  members  are  unacquainted 
with  its  early  history,  it  has  been  thought  that  some  account  of 
this  would  be  of  interest. 

Hardwicke's  Science  Gossip  was  started  in  January  1865,  and 
in  the  May  number  of  that  periodical  a  letter  appeared  from 
Mr.  W.  Gibson,  suggesting  that  a  Society  for  Amateur  Micro- 
scopists  on  similar  lines  to  those  of  the  Society  of  Amateur 
Botanists  (of  which  he  was  a  member)  would  be  desirable,  as 
being  a  means  of  bringing  together  those  having  similar  tastes, 
who  could  meet  to  discuss  difficulties  and  assist  one  another  in  a 
manner  not  provided  for  by  the  existing  Society.  Monthly  meet- 
ings and  a  small  subscription  were  proposed,  and  persons  interested 
in  the  matter  were  invited  to  co-operate.  The  Editor  of  Science 
Gossip  gladly  inserted  this  communication,  and,  being  himself  the 
President  of  the  Society  of  Amateur  Botanists  at  the  time,, 
entered  fully  into  the  project,  and  together  with  Mr.  W.  M„ 
Bywater  and  Thomas  Ketteringham  met  at  the  house  of  the 
former  in  Hanover  Square,  and  having  discussed  its  feasibility, 
decided  that  such  a  society  should  be  established,  and  should  be 
named  "  The  Quekett  Club  "  after  the  name  of  the  distinguished 
Professor  of  Histology  *  who  had  died  :a  short  time  previously, 

*  John  Thomas  Quekett,  b.  1815.  In  1856  he  succeeded  Prof.  Owen  as 
Conservator  of  the  Hunterian  Museum,  and  was  appointed  Professor  of 
Histology,  which  post  he  held  until  his  death.  He  was  elected  F.R.S.  in 
1860,  and  died  in  1861.  He  was  Secretary  of  the  Microscopical  Society  of 
London  for  nineteen  years.  His  Practical  Treatise  on  the  Use  of  the  Micro- 
scope is,  or  was,  well  known. 

Journ.  Q.  M.  C,  Series  II.— No   76.  30 


426        R.  T.  LEWIS  ON  THE  EARLY  HISTORY  OF  THE 

A  meeting  of  twelve  gentlemen  known  to  be  interested  in  the 
microscope  was  therefore  called,  and  took  place  on  June  14th, 
1865,  at  the  offices  of  Mr.  Robert  Hardwicke  in  Piccadilly.  This 
meeting  was  attended  by  eleven  out  of  the  twelve  summoned,  the 
chair  was  taken  by  Mr;  M.  C.  Cooke,  and  on  the  motion  of  Mr. 
W.  Gibson  it  was  unanimously  resolved  that  such  a  Club  should 
be  formed,  and  on  the  motion  of  Mr.  E.  Jaques  it  was  also 
unanimously  decided  that  a  provisional  Committee  of  five  gentle- 
men, with  Mr.  Bywater  as  Secretary,  should  be  appointed,  and 
charged  with  the  duty  of  deciding  as  to  the  best  means  of  carrying 
out  the  object  in  view,  and  to  report  the  result  of  their  delibera- 
tions to  an  adjourned  meeting  to  be  held  on  July  7th.  This 
meeting,  which  was  held  at  St.  Martin's  National  Schools,  was 
attended  by  about  sixty  gentlemen,  when  four  suggestions  made 
by  the  Committee  were  discussed  and  severally  put  to  the  meeting, 
it  being  eventually  decided  : 

(1)  That  the  new  society  should  be  called  the  Quekett 
Microscopical  Club. 

(2)  That  the  meetings  be  held  on  the  fourth  Friday  of  every 
month. 

(3)  That  the  subscription  be  10s.  per  annum,  payable  in 
advance,  and  be  considered  due  as  from  July  1st,  1865. 

(4)  That  the  business  of  the  Club  be  conducted  by  a  President, 
two  Vice-Presidents,  twelve  Members  of  Committee,  a  Secretary 
and  a  Treasurer. 

It  was  further  decided  that  the  provisional  Committee  should 
be  empowered  to  carry  on  the  business  of  the  Club  and  to  receive 
subscriptions  until  the  appointment  of  regular  officers  had  been 
duly  made ;  the  meeting  was  then  adjourned  until  August  4th, 
1865.  At  the  adjourned  meeting,  which  was  also  held  at 
St.  Martin's  Schools,  a  series  of  eleven  By-laws  were  passed, 
Dr.  Edwin  Lankester  was  elected  the  first  President  of  the  Club, 
with  Messrs.  M.  C.  Cooke  and  P.  le  Neve  Foster  as  Vice-Presi- 
dents, Mr.  Robert  Hardwicke  as  Treasurer,  Mr.  W.  M.  Bywater 


QUEKETT    MICROSCOPICAL    CLUB.  427 

Secretary,    and    twelve    members    to   serve    on   the    Committee. 

The  first  Ordinary  Meeting  was  held  on  August  25th,  1865,  in 

the    rooms   at    32,   Sackville   Street,    when   the    President   took 

the  chair  and   gave  an   interesting  inaugural  address,   and  the 

Quekett  Microscopical  Club  was  thus  fairly  started  on  what  has 

proved  to  be  a  successful  career.      The   rapid   increase  in    the 

number  of  members  soon  made  it  apparent  that  the  room  in 

Sackville  Street  was  not  large  enough  for  the  purpose,  and  the 

Eighth  Ordinary  Meeting  was  held  in  the  Library  of  University 

College,  kindly  placed  at  the  disposal  of  the  Club  by  the  Council 

of  the  College,  through  whose  courtesy  the  meetings  continued  to 

be  held  there  until  1889.     Dr.  Lankester  was  succeeded  in  the 

Presidency  by  Mr.   Ernest  Hart,  and  it   was  in   October  1866 

that   the   suggestion    was    made    that   the    proceedings    of    the 

Club  were  now  of  sufficient  importance  to  deserve  some  record, 

and  in   the  following  month  reports  were  taken  by  Mr.  R.  T. 

Lewis,  who  has  carried  out  this  duty  to  the  present  time.     The 

earlier   papers   read   at   the   meetings    were   in   some   instances 

published  in  the  Microscopical  Journal  or  in  Science  Gossip,  but 

they   were   subsequently   printed  in   the  Journal   of   the  Club, 

which  was  commenced  in  1868  under  the  editorship  of  Mr.  W. 

Hislop. 

The  first  Soiree  of  the  Club  was  held  at  University  College 
on   January    4th,    1867,  and  notwithstanding   a   heavy   fall    of 
snow    and    frost    of    exceptional    severity,    in    consequence    of 
which  vehicles  were   only  to  be   obtained  at  a  high  premium, 
it   was   attended    by   a   large    number   of   members   and   their 
friends,    and    was    deemed    to    have    been    a    decided    success. 
Profiting,  however,  by  the  experience  gained  on  this  occasion, 
future  Soirees   were   held   somewhat   later   in   the   year.      The 
number    of    members    at   the    end   of   the   second    year   of   the 
Club's  existence  was  273.     Eleven  Field  Excursions  took  place, 
the  Cabinet  contained  260  slides,  and  an  "Exchange  of  Slides 
Committee"  was  appointed. 


428        R.  T.  LEWIS  ON  THE  EARLY  HISTORY  OF  THE 

Mr.  Arthur  E.  Durham  was  the  third  President,  and  held  the 
office  for  two  years,  during  which  period  the  Journal  of  the  Club 
made  its  first  appearance,  the  extra  meetings  on  the  second 
Friday  in  each  month  were  commenced,  and  the  first  dinner  took 
place  at  Leatherhead,  Mr.  Suffolk's  classes*  were  restarted,  and 
the  number  of  members  was  reported  as  having  reached  512.  It 
was  towards  the  beginning  of  1868  that  a  member  of  the  Com- 
mittee began  to  agitate  for  the  admission  of  women  as  members, 
a  proposal  strongly  deprecated  by  his  colleagues  as  being  sub- 
versive of  the  interests  of  the  Club.  This  gave  rise  to  considerable 
opposition  from  the  members  generally,  and  much  merriment 
was  created  by  the  circulation  of  sketches  by  Mr.  Suffolk  and 
Mr.  Lewis,  and  by  the  issue  of  a  skit  purporting  to  be  the 
report  of  a  meeting  held  two  years  ahead  and  embodying  most 
of  the  objections  to  the  scheme.  It  was,  however,  formally- 
proposed  at  the  Ordinary  Meeting  in  March  1868,  Dr.  Tilbury 
Fox  in  the  chair,  but  on  the  resolution  being  put  it  found  only 
two  supporters,  and  was  therefore  negatived  by  an  overwhelming 
majority. 

At  the  Annual  Meeting  in  1869  Mr.  P.  le  Neve  Foster  suc- 
ceeded Mr.  Durham  as  President,  but  the  latter  took  the  chair 
at  the  November  meeting,  when  a  handsome  testimonial  was 
presented  to  Mr.  Bywater  on  his  retirement  from  the  position 
of  Secretary,  the  duties  of  that  office  having  been  taken  over 
by  Mr.  T.  C.  White.  In  1870  the  members  had  increased  so 
much  that  it  became  necessary  to  reduce  the  number  of  invitation 
tickets  issued  for  the  Annual  Soiree,  a  charge  being  made  for 

*  Mr.  W.  T.  Suffolk  conducted  a  class  for  beginners  during  the  winter 
of  1865-6  in  a  room  at  the  Society  of  Arts,  kindly  placed  at  his  disposal 
for  the  purpose  by  Mr.  P.  le  Neve  Foster.  At  this  he  gave  useful  and 
practical  information  on  the  management  of  the  microscope,  the  mounting 
of  objects,  etc.  The  class  was  suspended  during  the  summer  months,  but 
was  resumed  during  the  winter  of  1866-7,  and  was  fairly  well  attended 
but  as  there  is  no  later  mention  of  it,  I  infer  that  it  was  not  again  started,, 
but  occasional  demonstrations  at  the  Gossip  Meetings  seem  to  have 
taken  its  place. 


QUEKETT    MICROSCOPICAL    CLUB.  429 

those  wanted  in  excess,  the  sale  of  which  realised  =£5  7s.  Qd., 
a,nd  this  was  given  as  a  donation  to  University  College  Hospital. 
The  next  four  Presidents,  Dr.  Lionel  S.  Beale,  Dr.  Robert 
Braithwaite,  Dr.  John  Matthews  and  Mr.  Henry  Lee,  each  held 
the  office  for  two  years.  At  the  Annual  Meeting  in  1873 
Mr.  White  retired  and  was  succeeded  by  Mr.  J.  E.  Ingpen,  with 
Mr.  E.  Marks  as  Assistant  Secretary.  Mr.  Robert  Hardwicke, 
the  first  Treasurer  of  the  Club,  died  in  1875,  and  was  succeeded 
in  the  office  by  Mr.  F.  W.  Gay.  In  1878  Prof.  T.  H.  Huxley 
was  elected  President,  being  followed  by  Dr.  Spencer  Cobbold  in 
1879,  Mr.  T.  C.  White  in  1880  and  1881,  Dr.  M.  C.  Cooke  in 
1882  and  1883,  Dr.  W.  B.  Carpenter  in  1884,  Mr.  A.  D.  Michael 
in  1885,  1886  and  1887,  and  Mr.  B.  T.  Lowne  in  1888-9.  The 
<3ate  of  the  Annual  Meeting  was  altered  to  the  last  Friday  in 
February  in  1888. 

The  last  meeting  in  the  Library  of  University  College  was 
held  on  February  22nd,  1889,  but  the  Council  of  the  College 
generously  placed  their  Mathematical  Theatre  at  the  disposal 
of  the  Club.  This  room,  however,  was  found  unsuited  to  their 
purpose,  and  arrangements  were  made  for  removal  to  20,  Hanover 
Square.  This  necessitated  a  change  of  the  meeting  nights  to 
first  and  third  Fridays,  and  no  Ordinary  Meetings  were  after- 
wards held  in  July  and  August.  The  history  of  the  Club  during 
the  last  twenty-four  years  need  not  be  recorded  here,  as  all 
particulars  are  to  be  found  in  the  reports,  and  are  doubtless 
well  known  to  the  majority  of  the  members.  Briefly,  however, 
since  its  commencement  in  1855,  it  has  had  twenty-three  Presi- 
dents, seven  Secretaries,  and  has  published  sixteen  volumes  of  its 
Journal. 

Of  the  original  members  but  few  are  now  left,  and  of  those 
who  joined  in  the  first  year  only  two  now  are  seen  at  the 
meetings.  Mr.  W.  Gibson,  whose  suggestion  led  to  the  Club's 
formation,  does  not  appear  to  have  contributed  to  the  pro- 
ceedings,   though   he   continued   to    be   a   member  for  eighteen 


430     R.  T.  LEWIS,  EARLY  HISTORY  OF  QUEKETT   MICROSCOPICAL  CLUB, 

years.  Mr.  M.  C.  Cooke,  who  took  the  chair  at  the  preliminary 
meetings,  was  elected  an  honorary  member  in  1893,  and  con- 
tinued to  take  a  lively  interest  in  the  well-being  of  the  Club  up 
to  the  time  of  his  death,  which  occurred  in  his  ninetieth  year, 
only  a  few  months  ago. 


Journ.  Qutkett  Microscopical  Club,  Str.  2,  Vol.  XJL,  No.  7(5,  April  1915. 


431 


A  NEW  COPEPOD  FOUND  IN  WATER  FROM  HOLLOWS 

ON  TREE  TRUNKS. 

By  D.  J.  Scourfield,  F.Z.S.,  F.R.M.S. 
{Read  November  24th,  1914.) 

Plates  24  and  25. 

The  search  for  plants  and  animals  in  unusual  and  unlikely 
places  is  always  interesting,  and  may  be  sometimes  richly  re- 
warded. As  a  case  in  point,  and  the  one  which  led  directly  to  the 
discovery  of  the  new  species  of  Copepod  that  I  wish  to  describe 
in  this  paper,  we  may  consider  what  has  been  done  in  the 
elucidation  of  the  fauna  living  in  the  little  natural  cups  formed 
by  the  bases  of  the  leaves  of  plants  belonging  to  the  Order 
Bromeliaceae,  i.e.  the  order  to  which  the  pine-apple  belongs. 

It  was  in  1879  that  the  celebrated  naturalist  Fritz  Miiller, 
who  was  at  that  time  associated  with  the  National  Museum  in 
Rio  de  Janeiro,  called  attention  to  the  fact  that  the  water  con- 
tained in  the  little  cups  just  referred  to  was  tenanted  by  various 
forms  of  animal  life.  In  particular  he  described  a  new  Ostracod, 
representing  a  new  genus,  Elpidium  bromeliarum,  which  occurred 
almost  constantly  in  association  with  the  Bromeliaceous  plants 
in  the  forests  of  Brazil,  and  strangely  enough  was  to  be  found 
in  no  other  situation  (5,  6,  and  7). 

Since  that  date  a  number  of  other  investigators  have  from 
time  to  time  examined  these  little  collections  of  water  retained 
by  the  leaves  of  Bromeliaceous  plants,  and  I  may  here  mention 
that  soon  after  I  became  acquainted  with  the  work  of  Fritz 
Miiller  I  commenced  to  look  for  Entomostraca  in  these  situa- 
tions at  the  Royal  Botanic  Gardens,  Regent's  Park,  and  at  Kew. 
My  curiosity  was  gratified  by  finding  the  remarkable  blind 
Copepod,  Belisarius  viguieri,  which  had  not  previously  been 
found  in  this  country.*       In  recent  years  still   more  attention 

*  Kecorded  and  figured  in  Joum.  Q.  M.  C,  vol.  viii.,  November  1903, 
p.  539,  and  vol.  ix.,  April  1904,  PI.  2  (15).  For  further  notes  on  this  species 
see  also  The  Wild  Fauna  and  Flora  of  the  Royal  Botanic  Gardens,  Kew, 
p.  20  (16). 


432  D.    J.    SCOURFIELD    OX    A    NEW    COPEPOD    FOUND    IN 

has  been  given  to  the  subject  owing  to  the  endeavour  to  discover 
the  life-histories  of  mosquitoes  and  other  insects  supposed  to  be 
connected  with  the  dissemination  of  tropical  diseases.  Last  year 
a  very  elaborate  paper  was  published  by  Picado  (8),  in  which 
he  gives  details  of  the  facts  previously  elucidated,  and  of  his 
own  work  on  this  subject  in  Costa  Rica.  It  appears  that  no 
less  than  about  250  species  of  animals  have  been  found  living 
in  this  peculiar  environment,  49  being  new  to  science.  They 
belong  to  almost  all  groups  of  Invertebrates,  but  naturally 
insects  and  their  larvae  predominate.  The  Amphibia  are  also 
represented.  A  very  full  account  of  this  paper  has  been  recently 
published  by  H.  Scott  in  the  Zoologist  (12). 

When  once  this  peculiar  habitat  had  been  pointed  out,  it  was 
natural  that  somewhat  similar  situations  should  be  searched,  and 
records  have  indeed  been  made  of  animals  found  living  in  the 
pitchers  of  Pitcher-plants  and  Sarracenias,  the  holes  occurring 
occasionally  in  bamboos,  the  tops  of  palm  trees,  and  in  various 
other  places. 

It  occurred  to  me  that  perhaps  the  little  collections  of  water 
which  are  sometimes  to  be  found  in  the  hollows  and  crevices 
on  the  trunks  and  exposed  roots  of  trees  might  possibly  be 
inhabited  by  some  member  or  members  of  the  Entomostraca, 
the  group  in  which  I  am  more  particularly  interested.  This 
proved  to  be  the  case ;  at  least  I  am  now  able  to  report  that 
on  several  occasions  I  have  found  the  minute  Copepod  about 
to  be  described  in  such  little  reservoirs  of  water  on  trees  in 
Epping  Forest.  Up  to  the  present  it  has  been  found  nowhere 
else,  and,  on  the  other  hand,  I  have  never  found  any  other 
species  of  Entomostraca  in  the  same  places. 

The  new  species  evidently  belongs  to  the  Harpacticid  genus 
Moravia  T.  and  A.  Scott,  and  I  propose  to  call  it  M.  arboricola 
on  account  of  its  tree-dwelling  habit. 

The  genus  Moravia  is  very  closely  allied  to  the  well-known 
genus  Canthocamptus,  and  is,  in  fact,  even  now  included  in  the 
latter  by  some  authors.  It  was  instituted  by  T.  and  A.  Scott  in 
1893  (14)  for  a  species  found  in  Loch  Morar,  in  Scotland,  which 
they  named  M.  andevson-smithi,  believing  it  to  be  new,  but 
which  subsequently  proved  to  be  identical  with  C anthocamptus 
brevipes  Sars,  described  thirty  years  previously  (11).  A  month 
or  two  later  in  the  same  year,  1893,  Mrazek  described  as  new 


WATER  FROM  HOLLOWS  ON  TREE  TRUNKS.  433 

the  same  species,  placing  it  with  two  others  which  were  really 
new  to  science,  in  a  new  genus,  Ophiocamptus,  thus  showing  that 
he  also  recognised  the  necessity  of  separating  Sars's  C.  brevipes 
-and  closely  allied  forms  from  the  old  genus  C anthocamptus  (4). 

The  characteristics  of  the  genus  Moraria  are  chiefly  as 
follows :  Body  very  elongated,  almost  vermiform.  Rostrum 
broad.  First  antennae  seven-jointed.  First  four  pairs  of  feet 
with  three-jointed  outer  and  two-jointed  inner  branches.  Inner 
branches  of  first  pair  of  feet  only  a  little  shorter  than  the  outer 
branches,  with  the  basal  rather  longer  than  the  terminal  joint. 
Inner  branches  of  the  second,  third,  and  fourth  pairs  of  feet 
only  a  little  longer  than  the  first  joint,  or  at  most  only  as  long 
as  the  first  two  joints  of  the  outer  branches.  Furca  well  de- 
veloped, each  branch  tapering  considerably  from  base  to  tip,  and 
usually  (?  always)  furnished  with  a  strong  longitudinal  chitinous 
ridge  on  the  dorsal  surface. 

So  far  as  I  can  ascertain,  eight  species  of  Moraria  have  hitherto 
been  described  and  two  others  referred  to,  but  not  described. 
They  are  as  follows  : 

M.  brevipes  (G.  0.  Sars),  1863  =  C anthocamptus  brevipes  G.  0. 
Sars,  1863  (11);  M.  anderson-smithi  T.  and  A.  Scott, 
1893  (14) ;  Ophiocamptus  sarsi  Mrazek,  1893  (4). 

M.  mrdzeki  T.  Scott,  1903  (13),  new  name  only  =  Ophio- 
camptus brevipes  Mrazek,  1893  (4). 

M.  poppei  (Mrazek),  1893  (4)  =  0.  poppei  Mrazek,  1893  (4). 

M.  muscicola  (Richters),  1900  (9)  =  0.  muscicola  Richters, 
1900  (9). 

M.  schmeili  van  Douwe,  1903  (3). 

M.  mongolica  (Daday),  1906  (1  and  2)  =  0.  mongolicus  Daday, 
1906  (1  and  2). 

M.  wolfi  Richters,  1907  (10). 

M.  quadrispinosa  Richters,  1907  (10). 

M.  sp.  1  Richters,  1907  (10). 

M.  sp.  2  Richters,  1907  (10). 

Most,  if  not  all,  of  the  above  have  been  found  living  in  wet 
-or  damp  mosses  ;  some,  in  fact,  have  hitherto  been  found  in  no 
other  situations.  Only  the  first  three  have  been  found  in  the 
British  Isles. 


434      D.  J.  SCOURFIELD  ON  A  NEW  COPEPOD  FOUND  IN 

Moraria  arboricola  sp.  nov. 

Female. — Body  (fig.  1)  long  and  vermiform,  divided  into  nine 
free  segments,  the  first  being  the  longest  and  the  sixth  (first- 
abdominal)  the  second  in  length.  Rostrum  broad.  Eye  red  or 
brownish  red,  moderately  large  as  a  rule,  but  rather  variable  in 
size  and  in  outline.  Dorsal  plate  on  carapace  rather  variable 
in  shape,  usually  more  or  less  rectangular  with  rounded  anglesr 
slightly  broader  in  front  than  behind.  Posterior  margins  of  all- 
segments  smooth  on  dorsal  surface.  On  ventral  surface  abdominal 
segments  (fig.  16)  armed  as  follows:  1st,  with  two  widely 
separated  groups  of  about  five  teeth  ;  2nd,  with  a  row  of  teeth 
from  one-third  to  half  width  of  segment,  sometimes  with  central 
teeth  missing,  thus  leaving  two  isolated  groups;  3rd,  with  a  row 
extending  almost  across  segment ;  4th  (last),  with  a  row  com- 
pletely across  segment  and  a  little  way  round  sides,  except  for 
the  slight  interruption  caused  by  the  posterior  median  notch. 
Anal  plate  or  operculum  (see  fig.  15)  more  or  less  semicircular^, 
with  smooth  but  slightly  wavy  edge,  and  with  faint  dark  and 
light  bands  radiating  towards  the  edge,  showing  probably  that 
the  plate  is  very  slightly  corrugated. 

In  the  stage  before  the  adult  the  edge  of  the  anal  plate  is  not 
smooth,  but  furnished  with  a  few  very  minute  teeth,  widely  but 
somewhat  irregularly  spaced  (fig.  13).  In  the  still  earlier  stages 
the  teeth  are  rather  larger  (fig.  12).  The  presence  of  teeth  on 
the  anal  plate  in  the  young  stages  of  M.  brevipes,  which  also 
has  smooth  edges  in  the  adult,  has  been  noted  by  Mrazek  (4). 

Branches  of  furca  (figs.  14  and  15)  moderately  long  and  taper- 
ing considerably,  with  a  prominent  chitinous  ridge  on  the  dorsal 
surface,  ending  posteriorly  in  a  blunt  tooth  from  the  base  of 
which  springs  a  spine  directed  upwards.  Outer  edges  armed 
with  two  strong  spines,  the  proximal  with  a  minute  accessory 
spine  at  its  base.  Inner  edges  with  two  curved  rows  of  minute 
teeth,  terminating  dorsally  in  little  teeth  on  the  chitinous  plate. 
Posterior  edges  with  a  row  of  teeth  on  the  ventral  surface, 
covering  bases  of  terminal  setae.  Terminal  setae  usually  quite 
smooth,  three  on  each  furcal  lobe,  inner  very  small,  outer  not 
quite  half  the  length  of  the  median,  which  again  is  about  half 
the  body  length.  The  outer  and  median  setae,  especially  the 
latter,  somewhat  bulbous  at  the  base. 


WATER  FROM  HOLLOWS  ON  TREE  TRUNKS.  435 

First  antennae  (fig.  2)  rather  short  and  seven-jointed,  with  the 
olfactory  seta,  on  the  fourth    joint  reaching  only  to  about  the 
middle  of  the  last  joint.     Second  antennae  of    the  usual  type 
with  the  accessory  branch  (fig.  3)  very  small,  one-jointed,  bearing 
three  setae  at  the  tip.     First  pair  of  feet  (fig.   4)  small,  with 
three-jointed    outer    and    two-jointed    inner    branches.       Inner 
branch  not  quite  so  long  as  outer,  with  one  of  the  two  terminal 
setae  extremely  long  and  curved  at  the  tip.     Second,  third,  and 
fourth  pairs  of  feet  (fig.  6)  very  similar  to  one  another  with  the 
three-jointed  outer  branches  larger  than  in  the  feet  of  the  first 
pair,  but  with  the  two-jointed  inner  branches  smaller,  being  only 
a  little  longer  than  the  basal  joints  of  the  outer  branches.     The 
second  joints  of  the  inner  branches  of  the  second  and  third  pairs 
of  feet  carry  three  terminal  spines,  the  corresponding  joint  of  the 
fourth  pair  only  two.     Fifth  feet  (fig.  8)  consisting  of  two  joints, 
the  basal  being  extended  on  the  inner  side  considerably  beyond 
the  broadly  ovate  second  joint.     Inner  part  of  basal  joint  armed 
with   six   spines  somewhat  flattened,  with   rounded  tips  of  the 
type  found  in  M.  brevipes  Sars,  but  not  quite  so  broad  or  blunt. 
The  fourth  and  fifth  spines  from  the  inner  edge  arise  from  a 
little  sub-rectangular  projection  which  has  the  appearance  of  a 
pseudo-joint.     A  finely  pointed  spine  projecting  outwards  arises 
as  usual  from  the  lower  corner  of  the  outer  edge  of  the  joint. 
The  second  joint  armed  with  four  spines,  the  innermost  being 
of  the  same  type  as  those  on  the  basal  joint,  and  the  other 
three  being   finely   pointed    and  not  flattened.     The  median  of 
these  three  turns  outwards  across  the  outer  spine.     There  is  a 
little  thorn  on  the  inner  edge  of  this  joint  just  above  the  inner- 
most spine.     None  of  the  spines  on  the  fifth  feet  are  plumose, 
but   a  single  barb  usually  occurs  on  the  fifth  and   sixth  from 
the  inner  edge,  as  indicated  in  fig.  8.     Earlier  stages  of  the  fifth 
feet  are  shown  in  figs.  10  and  11. 

Eeceptaculum  seminis  (fig.  18),  lying  immediately  behind  and 
usually  covered  by  the  fifth  feet,  somewhat  complicated  in 
structure,  consisting  apparently  of  two  lateral  highly  chitinised 
convoluted  chambers  or  tubes  and  a  median  membranous  or 
muscular  cavity,  the  latter  sometimes  rhythmically  contracted 
and  expanded  by  two  lateral  muscles,  thus  forming  for  a  time 
a  kind  of  pulsating  organ. 

Chitinous   integument  of   body  and  furca  almost  everywhere 


436  D.    J.    SCOURFIELD    ON    A    NEW    C0PEP0D    FOUND    IN 

covered  with  minute  pits  only  readily  noticeable  under  a  1/1 2th  in. 
objective  (see  figs.  14,  15,  16  and  17).  Dorsal  surface  of  most 
of  the  thoracic  and  abdominal  segments  with  lines  of  excessively 
minute  teeth  arranged  in  various  ways  characteristic  of  the 
different  segments,  often  giving  the  impression  of  a  series  of 
scales  (fig.  17). 

Eggs  much  elongated  while  in  the  body,  only  one  or  two  on 
either  side,  forming  two  lateral  lines  extending  sometimes  from 
the  second  free  thoracic  to  the  last  abdominal  segment.  As  no 
ovisac  has  yet  been  observed,  it  may  be  that  the  eggs  are 
deposited  upon  extrusion  and  not  carried  about.* 

Length  without  terminal  setae,  l/50th  in.  to  l/40th  in. 

Male. — Very  similar  to  female  in  general  appearance,  but  body 
divided  into  ten  free  segments,  the  first  longest  and  the  seventh 
to  tenth  next  in  length  and  sub-equal.  Posterior  margins  of 
abdominal  segments  armed  on  ventral  surface  as  follows  :  1st, 
with  two  widely  separated  groups  of  two  spines  each  situated 
on  a  slight  prominence  forming  rudimentary  sixth  feet ;  2nd  and 
3rd,  with  a  row  of  teeth  about  half  the  width  of  the  segment ; 
4th  and  5th,  with  a  row  across  whole  width  of  segment.  Anal 
plate  as  in  female,  also  furcal  lobes  and  terminal  setae,  except 
that  the  two  little  curved  rows  of  teeth  on  the  inner  sides  of 
the  furca  are  not  so  well  developed.  The  edge  of  the  anal  plate 
is  toothed  in  the  young  stages  as  in  the  female. 

First  antennae  modified  in  the  usual  way  with  no  very 
characteristic  features.  First  four  pairs  of  feet  almost  exactly 
as  in  female  except  that  the  inner  branches  of  the  second,  third 
and  fourth  pairs  are  larger  and  specially  modified  as  follows  : 
2nd  (fig.  20),  with  a  thick  slightly  curved  process  (?  enlarged 
spine)  projecting  downwards  from  the  anterior  face  of  the  basal 
joint  and  probably  forming  with  the  second  joint  a  pincer  like 
apparatus;  3rd  (fig.  21),  with  second  joint  carrying  two  strong 
terminal  setae,  one  of  which  is  about  a  third  the  length  of  the 
other  and  shaped  like  the  blade  of  a  knife,  and  the  first  joint 
bearing  a  very  large  trailing  spine  curved  towards  the  base  ; 
4th  (fig.  7),  with  both  joints  leaf-like,  the  second  having  a 
curiously  twisted  little  spine  on  the  lower  outer  margin.  Fifth 
feet  (fig.  9)  simpler  than  in  female,  the  slightly  extended  part 
of  the  basal  joint  with  only  two  short  spines,  the  second  joint 

*  See  note  on  p.  440. 


WATER  FROM  HOLLOWS  ON  TREE  TRUNKS.  437 

of  a  more  elongated  and  rectangular  shape  with  a  spine  arising 
from  near  the  base  on  the  inner  edge,  and  four  spines  from  the 
distal  edge,  the  third  of  which  from  the  inner  side  turns  outwards 
across  the  outer  spine.  None  of  the  spines  are  of  the  flattened 
blunt  type  present  on  the  fifth  foot  of  the  female. 

The  spermatophore  (fig.  19)  is  flask  or  retort-shaped  with  very 
thick  walls,  the  outlet  tube  being  embedded  for  a  part  of  its 
length  in  a  mass  of  cementing  material.* 

Length  without  terminal  setae,  about  l/50th  in. 

As  regards  the  habits  of  M.  arboricola  not  very  much  can  be 
said.  They  are  not  very  good  swimmers,  their  movements  in  the 
open  water  being  best  described,  perhaps,  as  an  active  wriggling 
assisted  by  the  beating  of  the  feet  rather  than  as  true  swimming 
produced  chiefly  by  the  action  of  the  feet.  On  the  whole  they 
seem  to  prefer  moving  downwards  more  than  upwards  when  free 
from  support.  They  can,  however,  cling  very  strongly  even  to 
glass,  and  often  in  this  way  travel  about  the  sides  of  the  vessel  in 
which  they  are  kept.  Very  often  I  have  found  that  they  have 
clung  to  the  inside  of  the  pipette  whilst  being  transferred  from  a 
bottle  to  the  live-box.  When  placed  in  a  watch-glass  I  have  noticed 
on  several  occasions  that  a  tap  on  the  glass  had  the  effect  of  suddenly 
stopping  their  movements  just  as  if  they  were  feigning  death. 

As  already  mentioned,  M.  arboricola  has  only  been  found  in 
little  hollows  on  tree  trunks  in  Epping  Forest,  and  so  far  only 
in  the  Theydon  Bois  and  High  Beech  districts,  f  The  first 
specimens  were  found  in  1904  near  Theydon  Bois,  and  since  that 
date  the  species  has  been  obtained  many  times  either  actually 
living  in  the  water  and  sediment  or  developing  out  of  the  black 
earthy  deposit  taken  from  dry  hollows  and  placed  in  water.  It 
has  happened  on  several  occasions  that  no  trace  of  the  animals 
could  be  found  in  the  first  instance,  but  that  after  several  weeks,. 

*  This  peculiar  mass  can  be  seen  in  the  same  relative  position  while  the 
spermatophore  is  still  within  the  body  of  the  male.  It  seems  therefore  to 
be  a  constant  character  and  not  merely  a  temporary  feature  produced  at 
the  time  of  attachment  to  the  female. 

t  The  fact  that  so  many  of  the  Epping  Forest  trees  have  been  pollarded 
in  bygone  times  has  had  the  effect  of  largely  increasing  the  number  of 
cavities  and  hollows  on  their  heads  and  trunks  in  which  water  can 
accumulate  in  wet  weather,  thus  rendering  the  district  a  particularly 
favourable  one  for  the  study  of  the  fauna  and  flora  of  such  a  peculiar 
environment.  The  systematic  investigation  of  this  fauna  and  flora  is  much 
to  be  desired,  and  could  scarcely  fail  to  vield  valuable  results. 


438  D.    J.    SCOURFIELD    ON    A    NEW    COPEPOD    FOUND    IN 

or  even  a  month  or  two,  specimens  have  begun  to  appear.  From 
the  fact  that  the  females  have  not  been  observed  carrying  ovisacs  * 
it  seems  possible  that  the  eggs  are  dropped  into  the  sediment  to 
lie  dormant  for  a  time,  or  even  to  be  dried  up  and  so  perhaps 
blown  about  by  the  wind.  This  might  account  for  their  distribu- 
tion from  one  tree  to  another,  although  it  is  very  probable  that 
insects,  of  which  a  number  of  forms  occur  in  the  same  situations, 
may  also  be  a  means  of  dispersal.  In  this  connection  and  also  in 
relation  to  their  peculiar  habitat  the  wonderful  vitality  of  the 
animals  may  play  an  important  role.  They  seem  capable  of 
living  for  a  very  long  time  in  quite  small  quantities  of  water 
and  with  scarcely  any  food.  On  one  occasion  specimens  continued 
in  evidence  for  four  and  a  half  years  in  a  3-in.  x  1-in.  glass  tube 
in  which  the  collection  had  been  brought  home.  The  tube  con- 
tained nothing  in  the  way  of  food,  except  the  very  innutritious- 
looking  original  sediment,  and  nothing  was  added  during  the 
whole  time  but  a  little  clean  water.  Individual  specimens,  too, 
have  been  kept  for  months  in  very  small  tubes  with  only  the 
merest  trace  of  sediment  and  have  remained  perfectly  active. 
Such  powers  of  endurance  must  evidently  be  of  the  greatest 
value  to  them  in  their  natural  surroundings. 

Literature  Referred  to. 

1.  Daday,   E.   von.     Edesvizi  mikroskopi   allatok  mongoliabol. 

Math.  Termt.  Ert.,  Vol.  24,  1906,  pp.  34-77. 

2.  Daday,  E.  von.     Beitrage  zur  Kenntnis  der  Mikrofauna  des 

Kossogol-Beckens  in  der  Nordwestlichen  Mongolei.    Math. 
Nat.  Berichte  aus  Ungarn,  Vol.  26,  1913,  pp.  274-360. 

3.  Douwe,  C.  van.     Zur  Kenntniss  der  Sussuasser-Harpacticiden 

Deutschlands.    Zool.  Jahrbucher.    A  bt.  fiir  Systematize,  etc., 
Vol.  18,  1903,  pp.  383-400. 

4.  Mrazek,  A.     Beitrag  zur  Kenntniss  der  Harpacticiden  fauna 

des  Siisswassers.     Zool.  Jahrbucher.     Abt.  f.   Systematic, 
etc.,  Vol.  7,  1893. 

5.  Muller,  F.     Descripgao  do  Elpidium  bromeliarum  crustaceo 

da  familia   dos  Cythei icleos.      Arch.   Museu  National  do 
Rio  de  Janeiro,  Vol.  4,  1879,  pp.  27-34. 

6.  Muller,  F.     Phryganiden-Studien.     3.  Wasscrthiere  in  den 

Wipfeln  des  Waldes.     Kosmos,  Vol.  4,  1879,  pp.  390  392. 

*  See  note  on  p.  440. 


WATER    FROM    HOLLOWS    ON    TREE   TRUNKS.  439 

7.  Muller,     F.      Wasserthiere    in    Baumwipfeln.       Elpidium 

bromeliarum.     Kosmos,  Vol.  6,  1880,  pp.  386-388. 

8.  Picado,  C.     Les  Bromeliacees  epiphytes,  considerees  comme 

milieu  biologique.  Bull.  Scientifique  de  la  France  et  de 
la  Belgique,  Vol.  47,  1913,  pp.  215-360. 

9.  Richters,     F.        Bfitrage    zur    Kenntnis    der    Fauna    der 

Umgegend  von  Frankfurt  a.  M.,  III.  Ophiocamptus 
muscicola  n.  sp.,  ein  moosbewohnender  Copepode.  Bericht 
der  Senckenbergischen  N  aturforschenden  Gesellschaft,  1900, 
pp.  36-39  (also  further  notes  in  the  same  publication, 
1902,  pp.  6-7). 

10.  Richters,  F.     Die  Fauna  der  Moosrasen  des  Gaussbergs  und 

einiger  siidlicher  Inseln.  Deutsche  Slid-polar  Expedition, 
1901-1903,  Vol.  9,  1907. 

11.  Sars,  G.  O.     Oversigt  af  de  indenlandske  Ferskvands  Cope- 

poder.  Vidensk.-Selsk.  i  Christiania  Forhandl.  for  1862 
(Aftr.),  1863,  p.  24. 

12.  Scott,    H.     The    Fauna    of    "Reservoir-plants."      Zoologist, 

Vol.  18,  1914,  pp.  183-195. 

13.  Scott,  T.     Some  Observations  on   British  Freshwater  Har- 

pacticids.  Annals  and  Magazine  Nat.  Hist.,  Series  7, 
Vol.  11,  1903,  pp.  185-196/ 

14.  Scott,  T.  and  A.     On  some  new  or  rare  Scottish  Entomo- 

straca.  Annals  and  Magazine  Nat.  Hist.,  Series  6, 
Vol.  11,  1893,  pp.  210-215. 

15.  Scourfield,  D.  J.     Synopsis  of  the  known  species  of  British 

Freshwater  Entomostraca,  Part  II.  and  Part  III.  (Plate). 
Journal  Quekett  Micro.  Club,  Series  2,  Vol.  8,  1903, 
p.  539,  and  Vol.  9,  1904,  p.  44. 

16.  Scourfield,  D.  J.     The  Wild  Fauna  and  Flora  of  the  Royal 

Botanic  Gardens,  Kew.  Crustacea,  Entomostraca. 
Bulletin  of  Miscellaneous  Information,  Additional  Series  V. 
(Royal  Botanic  Gardens,  Kew),  1906,  pp.  14-20. 

Explanation  of  Plates  24  and  25. 

Moraria  arboricola  sp.  nov. 

Fig.  1.  Dorsal  view  °,  x  200. 
,,     2.  First  antenna  ?  ,  x  700. 
,,     3.  Accessory  branch  of  second  antenna 


55 
55 
» 


440  D.    J.    SCOURFIELD    ON    A    NEW    COPEPOD. 

Fig.     4.  First  foot  ? ,  x  6C0. 

5.  Seta  on  inner  angle  of  basal  joint  of  first  foot  <$ . 

6.  Fourth  foot  ?,  x  600. 

7.  Inner  branch  of  fourth  foot  J1,  x  1000. 
„       8.  Fifth  foot  ?,  x  1000. 

„       9.     ,,         „     S,  x  700. 

10.  „         „    young  ?  (antepenultimate  stage). 

11.  „         „       „         $  (penultimate  stage). 

12.  Anal  plate,  young  (three  stages  before  adult). 

13.  „  „  „       (penultimate  stage). 

14.  Last  abdominal  segment  and  furca  from  side    ?/x  700, 

15.  „  „  ,,  ,,       „     dorsal  view  ? ,  x  700, 

16.  „     3      ,,  segments    ,,       „     ventral  view  ¥  (some- 
what flattened  and  contracted),  x  350. 

17.  First  and  second  abdominal   segments,  dorsal  view    ?y 
X  350. 

18.  Receptaculum  seminis  $,  x  900. 

19.  Spermatophore,  x  400. 

20.  Inner  branch  of  second  foot  $  (from  left  side),  x  500. 

21.  „         „         „  third       „     <?,  x  500. 


5> 

J) 
)) 
>> 

55 


55 


Note  added  April  1915. 

A  single  individual  of  M.  arboricola  has  now  been  seen  carrying 
an  ovisac  containing  four  eggs,  the  latter  being  almost  perfect 
spheres  l/500th  inch  in  diameter.  The  ovisac  itself  was  very 
delicate  and  soon  became  detached,  and  also  separated  into  two 
parts,  each  containing  two  eggs,  by  the  movements  of  the  animal 
when  lightly  held  in  the  live-box. 

Nauplii  in  various  stages  have  also  been  seen.  The  earlier 
forms  exhibit  a  somewhat  elaborate  structure  on  the  back,  con- 
sisting of  three  pairs  of  papillae  with  pointed  tips  lying  between 
two  strong  lateral  thorns.  Whether  this  is  characteristic  of  the 
species  or  not  is  unknown. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  N:  76,  Ap      1915. 


Journ.Q.M 


Sep.  2  ai,P1.24. 


Scourfield  del. ad 


■-Newman  lith. 


■ 


Jour- 


Ser.2  25. 


\ 


Wrv^ 


!0 


(J 


. 


j'/fVl/Vi'Wi       -YJCWW 


ScourfielddeLadnat.  West,Newn  u 

kria  arborieola   sp.nc 


441 


SOME  DETAILS  IN  THE  ANATOMY  OF  THE  RAT-FLEA, 
CERATOPHYLLUS  FASCIATUS  BOSC. 

By  Prof.  E.  A.  Minchin,  M.A.,  Hon.  Ph.D.,  F.R.S. 

{Bead  January  2Qth,  1915.) 

Plates  26-32. 

During  the  past  five  years  I  have  been  engaged,  in  collaboration 
with  a  friend,  upon  investigations,  recently  published,*  into  the 
development  of  the  rat-trypanosome  in  its  invertebrate  host  the 
rat-flea  (Ceratophyllus  fasciatus).  In  the  course  of  this  investi- 
gation we  have  dissected  and  examined  some  1,700  fleas ;  and 
although  these  dissections  were  not  undertaken  with  the 
primary  object  of  studying  the  anatomy  of  the  flea,  but  only 
with  the  intention  of  extracting  and  examining  those  organs  of 
the  flea  likely  to  contain  stages  of  the  trypanosome,  it  goes 
without  saying  that  we  have  not  pulled  so  many  fleas  to  pieces 
without  gaining  some  insight  into  the  structure  of  the  insect, 
and  it  seemed  to  me  worth  while  to  study  some  anatomical  points 
of  structure  in  more  detail  and  in  special  preparations.  Some 
parts  of  the  flea  are  very  interesting  as  regards  their  structural 
relations  and  make  very  beautiful  microscopic  preparations  which 
can  be  mounted  with  very  little  trouble.  I  thought  it  might 
interest  the  members  of  the  Club  if  I  laid  before  them  a  brief 
account  of  some  points  of  flea-anatomy  seen  by  the  way — obiter 
visa,  if  I  may  use  the  expression, 

Before  describing  these  observations,  I  wish  it  to  be  clearly 
understood  that  this  paper  does  not  pretend  to  give  a  complete 
anatomical  description  either  of  the  flea  as  a  whole  or  even  of 
the  systems  of  organs  that  are  dealt  with.  There  are  many 
structural  details  which  could  only  be  made  out  by  sections,  and 
I  have  had  no  leisure  for  the  task  of  section-cutting,  always  a 
difficult  and  laborious  undertaking  in  the  case  of  insects,  on 
account  of  the  toughness  of  the  chitinous  cuticle,  which  cannot 

*  Minchin  and  Thomson,  "  The  Rat-trypanosome,  Trypanosoma  lewisi, 
in  its  Relation  to  the  Rat-flea,  Ceratophyllus  fasciatus"  Quarterly 
Journal  of  Microscopical  Science,  Vol.  LX.,  Part  4,  1915. 

Journ.  Q.  M.  C,  Series  II. — No.  76.  31 


442       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

be  dissolved  out.  I  do  not  propose  to  describe  any  details  here 
which  cannot  be  verified  by  an  observer  possessing  a  dissecting 
microscope  *  and  a  pair  of  mounted  dissecting  needles — and  a 
flea  !  In  fact  the  results  obtained  by  me  and  set  forth  here  are 
based  entirely  on  what  may  be  termed  "  needlework." 

Before  proceeding  to  anatomical  descriptions,  I  may  give  a 
brief  account  of  the  technique  I  have  employed.  The  flea  at 
liberty  is,  I  need  not  say,  an  active  and  elusive  insect.  But 
when  placed  on  the  surface  of  water,  he  is  perfectly  helpless,  and 
floats  there  without  being  able  to  escape  and  without  drowning 
for  at  least  twenty-four  hours,  provided  there  is  no  soap  in  the 
water ;  if  there  is  a  trace  of  soap  the  cuticle  of  the  flea  is  wetted 
and  the  insect  sinks  and  is  soon  drowned.  (This  hint  may  be 
borne  in  mind  as  being  often  useful  in  the  home.) 

Having  therefore  caught  your  flea,  put  it  on  the  surface  of 
some  water  and  keep  it  until  you  can  proceed  further  with  your 
operations.  An  expeditious  way  of  catching  the  flea  is  to  get 
it  to  hop  straight  on  to  the  surface  of  water.  In  doing  this 
remember  that  a  flea  always  hops  by  preference  away  from  the 
source  of  light,  never  towards  it. 

When  it  is  desired  to  dissect  the  flea  it  should  be  gathered  off 
the  surface  of  the  water  with  a  fine  forceps  and  placed  in  a  drop 
of  physiological  salt-solution  (0*75  gramme  sodium  chloride  in  100 
cubic  centimeters  of  distilled  water)  on  an  ordinary  microscopical 
slide,  which  is  then  placed  on  the  stage  of  the  dissecting 
microscope. 

For  the  dissection  I  use  two  fine  needles  mounted  in  wooden 
handles.  Each  needle  after  fixing  in  the  handle  is  ground  down 
further  on  an  ordinary  hone.  One  of  them  is  ground  to  a  fine 
sharp  point,  the  other  to  a  flat  cutting  edge.  For  preparing  the 
flat-edged  needle,  I  first  take  a  penknife  and  pare  the  extremity 
of  the  wooden  handle  on  both  sides  so  that  it  is  shaped  like  an 
ordinary  brad-awl.  I  then  rub  the  needle  down  on  the  hone  in  two 
planes  parallel  to  the  two  cuts  made  in  the  handle,  checking  the 
process  under  the  dissecting  microscope  and  trying  to  get  a 
rounded  cutting  edge,  not  an  edge  which  terminates  in  a  straight 
line  like  an  ordinary  chisel.  The  object  of  paring  the  wooden 
handle  is  both  to  guide  the  hand  when  rubbing  down  the  needle 

*  I  have  used  in  all  my  work  a  Greenough  binocular  dissecting 
m'croscope  made  by  Zeiss. 


THE    RAT-FLEA,    CERATOPHYLLUS  FASCIATUS   BOSC.  443 

on  the  hone,  and  also  to  distinguish  the  flat-edged  needle  from 
the  pointed  one.  When  dissecting  I  use  the  pointed  needle  in 
my  left  hand  for  holding  the  object,  and  the  flat-edged  needle  in 
my  right  hand  for  cutting.  The  needles  should  be  pushed  far 
into  the  wooden  handle,  so  that  only  a  short  length  is  free,  other- 
wise the  needle  is  too  springy  and  is  liable  to  snap  under 
pressure. 

The  flea  was  left  in  the  drop  of  salt-solution,  where  it  is  kicking 
about  violently  and  may  succeed,  if  not  watched,  in  getting  out 
on  to  the  slide  and  hopping  off*.  It  is  therefore  best  to  begin  by 
decapitating  the  flea.  This  can  be  done  by  holding  it  still  with 
the  pointed  needle  and  snipping  off  the  head  with  the  flat-edged 
needle.  The  dissection  can  then  be  proceeded  with  in  a  manner 
free  from  haste  or  anxiety. 

I  will  describe  now  a  method  of  making  permanent  preparations 
of  the  organs  of  the  flea  which  I  have  found  very  useful.  There 
is  not  a  single  detail  of  anatomy  described  in  this  paper  which  I 
could  not  demonstrate  to  a  sceptic  in  my  permanent  preparations  * 
at  a  moment's  notice.  Let  us  take  the  abdominal  nervous  system, 
for  example.  The  complete  nervous  system  of  the  flea  consists, 
as  in  other  insects,  of  the  three  sets  of  nerve-ganglia:  (1)  the 
cephalic  ganglion -complex,  or  brain,  situated  in  the  head  dorsal 
to  the  digestive  tract  (supra-oesophageal) ;  (2)  three  pairs  of 
thoracic  ganglia,  corresponding  to  the  three  thoracic  segments  : 
(3)  a  chain  of  abdominal  ganglia  extending  into  the  abdomen. 
Parts  (2)  and  (3)  are  ventral  to  the  digestive  tract  and  constitute 
a  continuous  chain  of  pairs  of  ganglia,  but  the  two  ganglia  of  any 
given  pair  are  fused  together  so  as  to  appear  like  a  single  ganglion- 
mass.  Each  pair  of  ganglia  is  connected  with  the  pair  next 
behind  or  in  front  by  a  pair  of  stout  nerves,  known  as  "  connec- 
tives," and  it  can  be  plainly  seen  that  these  connectives  remain 
distinct  in  each  pair,  and  are  not  fused  together  like  the  ganglion- 
pairs  (PI.  26).  The  first  pair  of  thoracic  ganglia  is  connected 
with  the  brain  by  a  pair  of  peri-oesophageal  connectives.  From 
the  ganglia  are  given  off*  nerves  to  the  various  organs  of  the  body. 

It  is  almost  impossible  to  dissect  out  the  brain,  and  to  study  its 

structure  and  relations  sections  would  be  necessary.    It  is  difficult, 

but  by  no  means  impossible,  to  dissect  out  the  thoracic  ganglia. 

Major   Christophers,    I. M.S.,   who    worked  for   a   time   in    my 

*  These  preparations  are  now  the  property  of  the  Club. 


444       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

laboratory  at  the  Lister  Institute,  made  some  beautiful  dissections 
of  the  ventral  nervous  system  of  the  flea,  showing  both  thoracic 
and  abdominal  ganglia  in  continuity.  On  the  other  hand,  it  is  by 
no  means  difficult  to  dissect  out  the  abdominal  chain  in  its  whole 
length,  up  to  and  including  the  large  metathoracic  ganglia,  the 
ganglia  of  the  jumping  legs.  To  do  this  the  flea  should  be  held  by 
the  thorax  with  the  pointed  needle,  while  with  the  flat -edged  needle 
the  abdominal  segments  are  carefully  detached  and  pulled  off 
from  behind  forwards  successively,  until  only  the  thoracic  segments 
are  left.  If  the  operation  has  been  successfully  performed,  and 
the  abdominal  segments  together  with  the  contained  digestive 
and  reproductive  organs  removed,  the  abdominal  chain  of  ganglia 
will  be  seen  proceeding  from,  and  adhering  to,  the  hindmost 
thoracic  segment.  With  practice  the  complete  severance  of  the 
abdomen  and  its  organs  from  the  thorax  can  be  effected  with  one 
pull. 

Now  take  another  slide  and  place  on  it  a  cover-slip  (|  inch 
square).  Place  the  slide  and  cover-slip  on  the  stage  of  the  dis- 
secting microscope,  put  a  quite  small  drop  of  salt-solution  on  the 
cover-slip,  and  transfer  the  thorax  of  the  flea  from  the  slide  on 
which  it  was  dissected  to  the  small  drop  of  fluid  on  the  cover-slip, 
and  there  proceed  with  the  dissection.  The  big  metathoracic 
ganglion-mass  can  be  seen  quite  plainly  in  the  hindermost  part 
of  the  thorax,  with  the  abdominal  chain  of  ganglia  proceeding 
from  it.  With  the  needles  the  metathoracic  ganglion  must  be 
carefully  dissected  out  and  set  free  from  the  thorax ;  this  operation 
is  not  at  all  difficult,  though  it  requires  both  skill  and  practice  to 
dissect  out  the  first  two  thoracic  ganglia  as  well,  in  unbroken 
continuity  with  the  rest  of  the  ganglionic  chain.  If  during  the 
dissection  the  cover-glass  slips  about  on  the  slide,  it  can  be  fixed 
quite  firmly  by  letting  a  tiny  drop  of  distilled  water  run  in  between 
cover-glass  and  slide,  but  I  avoid  this  as  a  rule,  because  it  makes 
it  difficult  to  get  the  cover-slip  off  later  on. 

When  the  dissection  has  been  completed,  the  fragments  and 
debris  of  the  thorax  should  be  removed  and  cleaned  up  as  much 
as  possible,  leaving  the  nervous  system  in  the  small  drop  of  fluid 
on  the  cover -slip.  Now  the  cover-slip  must  be  lifted  carefully  off 
the  slide  and  all  superfluous  moisture  drained  off  it,  so  as  to  leave 
the  nervous  system  stranded  on  the  cover-slip,  as  near  the  centre 
as  possible.     The  fluid  can  be  drained  off  either  by  tilting  the 


THE    RAT- FLEA,    CERATOPHYLLUS  FASCIATUS    BOSC.  445 

cover-glass  and  letting  the  salt-solution  run  off,  or,  if  the  nervous 
system  shows  a  tendency  to  run  off  with  the  fluid,  by  holding  the 
cover-glass  flat  and  carefully  mopping  up  all  superfluity  of  fluid 
with  a  small  piece  of  filter-paper.  The  object  to  be  attained  is  to 
leave  the  specimen  stranded  on  the  cover-glass  and  to  drain  off  as 
much  of  the  salt-solution  as  possible,  in  order  that  by  capillary 
attraction  the  object  may  be  pressed  against  the  cover-slip ;  but 
on  no  account  must  the  fluid  be  allowed  to  dry  completely.  When 
this  has  been  done  the  cover-slip  is  inverted,  so  that  the  object  is 
on  its  lower  side ;  and  then  it  is  dropped  face  downwards  quite 
flat  on  to  the  surface  of  some  fixative  fluid. 

Various  fixatives  can  be  used,  but  I  have  nearly  always  made 
use  of  5  per  cent,  sublimate-acetic — that  is  to  say,  saturated 
solution  of  corrosive  sublimate  in  distilled  water,  95  volumes, 
mixed  with  glacial  acetic  acid,  5  volumes.  When  fixing  the 
preparation  some  of  the  fixative  is  put  into  a  large  watch-glass 
or  clock-glass  and  the  cover-glass  with  the  adherent  object  is 
dropped  on  to  it  and  remains  floating  on  the  surface  of  the 
solution.  In  nine  cases  out  of  ten  the  object  remains  firmly 
adherent  to  the  under  side  of  the  cover-glass,  if  one  has  hit  the 
happy  medium  in  draining  off  the  fluid  in  which  it  was  dissected 
out.  If  superfluity  of  the  salt-solution  remains,  the  object  will 
come  off;  if  it  has  been  allowed  to  dry  up  altogether,  the 
preparation  is  ruined. 

The  cover-glass  with  the  adherent  organs  can  now  be  mani- 
pulated just  as  if  it  was  a  smear,  lifting  the  cover-slip  with  an 
ordinary  forceps  and  transferring  it  from  one  liquid  to  another. 
After  the  preparation  has  been  fixed  in  the  sublimate-acetic  for 
some  time,  say  from  10  minutes  to  an  hour,  it  can  be  brought 
up  through  successive  strengths  of  alcohol  in  watch-glasses 
(10  per  cent.,  30  per  cent.,  50  per  cent,  and  70  per  cent.)  to 
90  per  cent,  alcohol,  in  which  it  should  be  left  for  a  longer  time 
(preferably  over  night,  or  as  long  as  is  convenient)  in  order  that 
the  preparation  may  be  well  hardened  and  the  corrosive  sublimate 
thoroughly  dissolved  out.  In  the  stronger  alcohols  the  cover-slip 
will  sink,  but  it  rests  on  its  corners  on  the  rounded  bottom  of 
the  watch-glass  and  there  is  no  contact  or  pressure  on  the  object, 
which  of  course  is  on  the  under  side  of  the  cover-slip.  It  is  now 
apparent  why  square  cover-slips  must  be  used,  since  they  rest  on 
their  corners  and   can  be   easily   picked  up  with    the   forceps  : 


446       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

round  cover-slips  would  be  in  contact  with  tbe  watch-glass  round 
their  whole  edge,  and  be  very  troublesome  to  lift  up  with  the 
forceps  or  in  any  other  way. 

Sometimes  the  object  comes  away  loose  from  the  cover-slip  in 
the  sublimate-acetic.  When  this  annoying  event  takes  place,, 
put  the  cover-slip  into  a  watch-glass  and  cover  it  with  30  per  cent, 
alcohol;  then  draw  up  the  object  from  the  sublimate-acetic 
mixture  with  a  glass  pipette  of  sufficiently  wide  calibre  and  place 
it  on  the  upper  surface  of  the  cover-slip  in  the  alcohol.  Then  lift 
up  the  cover-slip  carefully  with  a  forceps,  taking  care  the  object 
does  not  float  off  the  cover-slip  to  one  side  or  the  other,  but 
remains  stranded  on  the  cover-slip  again.  Then  drain  off  the 
alcohol,  invert  the  cover-slip,  and  drop  it  face  downwards  into 
50  per  cent,  alcohol  in  another  watch-glass.  This  time  the 
rebellious  object  always  sticks  to  the  cover-slip.  In  all  cases  the 
cover-slips  should  be  handled  delicately  while  in  the  sublimate- 
acetic  or  in  the  weak  alcohols,  since  a  too  violent  jerk  may 
dislodge  them  ;  but  I  have  never  known  an  object  to  come  loose 
after  it  has  got  so  far  as  the  70  per  cent,  alcohol. 

I  have  described  this  method  in  full  detail  because  I  have 
found  it  extremely  useful  for  making  permanent  preparations 
of  dissections.  In  the  flea,  for  example,  it  is  very  easy  to  dissect 
out  and  mount  in  this  way  the  entire  male  reproductive  system, 
from  testes  to  penis,  and  so  display  every  detail  of  it ;  and  since 
the  preparation  is  adherent  to  the  cover-slip,  any  powers  of  the 
microscope,  even  immersion  lenses,  can  be  focused  on  to  it  for 
study  of  minute  details.  The  principle  of  the  method  is  that 
cellular  tissues,  having  been  pressed  firmly  but  gently  against 
the  glass  by  capillary  attraction,  adhere  to  the  glass  by  their 
own  stickiness  ;  and  when  the  preparation  has  been  well  fixed 
and  hardened,  the  coagulation  of  the  albumins  glues  the  organs 
so  firmly  that  they  cannot  be  detached  without  breaking 
them.  Naturally  this  does  not  apply  to  chitinous  organs, 
which  are  not  wetted  by  water,  and  can  never  be  made  to  stick 
in  this  way. 

The  preparations,  after  having  been  fixed  and  hardened,  can 
be  mounted  unstained,  or  can  be  stained  first  in  any  way  desired.. 
Unstained  preparations  are  best  for  showing  internal  details  of 
the  chitinous  cuticle  or  skeleton ;  stained  preparations  for 
showing  the  cellular  structure  of  the  tissues  and  soft  parts ;  the 


THE    RAT-FLEA,    CERATOPHYLLUS  FASCIATUS   BOSC.  447 

one  method  of  preparation  supplements  the  other.  For  staining 
an  alcoholic  stain  is  preferable,  since  prolonged  soaking  in  watery 
stains  might  produce  maceration  and  cause  the  object  to  become 
detached  again  from  the  cover-slip.  I  have  always  used  Gren- 
adier's alcoholic  borax-carmine,  in  which  the  objects  are  stained 
for  about  five  minutes,  and  then  transferred  to  acidulated  alcohol 
(0*1  per  cent,  hydrochloric  acid  in  70  per  cent,  alcohol),  in  order 
to  extract  all  the  carmine  stain  from  the  cytoplasm  of  the  cells 
and  leave  it  only  in  the  nuclei.  If  the  stain  be  not  thoroughly 
extracted  in  this  way  the  preparation  will  be  very  opaque,  and 
I  find  it  best  to  leave  the  objects  in  the  acidulated  alcohol  for  about 
forty-eight  hours,  changing  the  fluid  occasionally.  I  believe  this 
method  could  be  improved  upon,  and  that  Mayer's  alcoholic 
paracarmine  *  would  give  a  more  transparent  stain,  and  one 
more  easily  extracted.  Some  of  the  well-known  haematoxylin 
mixtures  would  probably  also  give  good  results. 

The  stained  or  unstained  preparations  are  then  finished  off  by 
passing  them  into  absolute  alcohol,  then  into  oil  of  cloves  or  any 
other  of  the  ordinary  clearing  reagents,  and  finally  into  Canada 
balsam.  The  cover- slips  can  be  mounted  over  well-slides  or — 
preferably,  in  my  opinion — on  ordinary  slides,  with  the  precau- 
tion of  supporting  the  corners  of  the  cover-slip  on  wax  feet  or  in 
some  other  way,  in  order  that  the  objects  may  run  no  risk  of 
being  crushed  between  slide  and  cover-slip. 

I  will  now  proceed  to  set  forth  some  of  my  observations  on  the 
anatomy  of  the  flea,  noting,  as  a  preliminary,  that  all  my  state- 
ments apply  to  the  common  rat-flea,  Ceratophyllus  fasciatusy 
the  only  species  I  have  dissected.  Other  species  of  flea  may 
perhaps  show  slight  differences  in  some  points. 

It  is  also  my  pleasant  duty,  at  this  point,  to  express  my  warm 
thanks  to  Miss  Mabel  Rhodes,  artist  at  the  Lister  Institute,  for 
kindly  executing  the  drawings  of  my  dissections  which  accompany 
this  paper.  They  were  all  drawn  with  the  camera  lucida  from 
the  actual  preparations. 

I.  The  Abdominal  Nervous  System. 

The  method  of  dissecting  out  the  abdominal  chain  of  nerve- 
ganglia    has   been    described    above.      It   is    one  of   the  easiest 

*  For  an  account  of  these  stains  and  how  to  prepare  them  see  Bolles 
Lee's  well-known  Vade-mecum. 


448       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

dissections  if  one  is  content  to  get  out  only  the  large  meta- 
thoracic  ganglion-mass,  in  the  thoracic  series,  and  not  to  worry 
about  the  ganglia  of  the  first  two  thoracic  segments,  which 
require  very  careful  dissection. 

A  remarkable  feature  of  the  abdominal  nervous  system  is  that 
it  presents  very  marked  differences  in  the  two  sexes  of  the  flea. 
These  sexual  differences  are  seen  at  a  glance  in  the  two  figures 
on  PI.  26,  which  are  drawn  from  two  preparations  to  the  same 
scale  by  means  of  a  camera  lucida.  At  the  upper  end  of  each 
figure  we  see  the  large  metathoracic  ganglion-mass,  and  at  the 
lower  end  the  large  hindmost  or  terminal  ganglion-complex  from 
which  nerves  are  given  off  to  the  genitalia.  Between  these  two 
larger  nerve-centres  at  the  two  extremities  there  is  a  series  of 
smaller  ganglia ;  and  it  is  easy  to  see  that  this  series  comprises 
seven  ganglia  in  the  male  and  only  six  in  the  female.* 

It  is  seen,  then,  that  the  male  flea  has  one  pair  of  ganglia 
more  in  its  abdominal  nervous  system  than  the  female.  Is  this 
an  indication  of  superiority  on  the  part  of  the  male  sex  ?  By 
no  means,  rather  the  contrary  !  In  the  embryonic  development 
of  insects  there  are  some  ten  or  eleven  pairs  of  abdominal  ganglia, 
and  in  the  ontogenetic  development,  or  in  the  phylogenetic 
ovolution,  of  insects  the  tendency  is  for  these  ganglia  to  be 
concentrated  by  fusion  which  takes  place  progressively  from 
behind  forwards.  In  some  of  the  Diptera — the  tsetse-fly,  for 
example,  and  I  believe  in  the  common  house-fly  also — the 
concentration  of  the  nerve-ganglia  has  reached  its  maximum 
possible,  since  the  whole  ventral  chain  is  concentrated  into  one 
large  mass  situated  in  the  thorax,  a  mass  which  represents  the 
three  pairs  of  thoracic  ganglia  plus  the  whole  abdominal  chain, 
all  telescoped  forwards  into  one  large  ganglion-complex.  In  the 
flea,  however,  the  process  of  concentration  and  specialisation  has 
not  gone  so  far,  and  is  seen  only  at  the  hindmost  end  of  the 

*  This  curious  point  was  discovered  by  Major  Christophers,  in  his 
dissections  of  fleas  made  in  my  laboratory.  Previous  to  his  work,  I  had 
counted  the  ganglia  of  a  female  flea  that  I  was  dissecting,  and  had  noted 
that  there  were  six  small  ganglia.  Subsequently  I  made  a  mounted  pre- 
paration of  the  abdominal  chain  of  a  male  flea,  and  was  surprised  to 
observe  seven  small  ganglia  ;  thinking  I  had  made  a  mistake  in  my  former 
observation,  I  looked  up  my  old  notes  and  altered  "  six "  to  "  seven, ' 
never  suspecting  the  sexual  differences  which  were  subsequently  shown  to 
exist. 


THE    RAT- FLEA,    CERATOPIIYLLUS  F  ASCI  ATI'S    BOSC.  449 

nervous  system,  in  the  large  terminal  ganglion-mass,  which 
represents  a  fusion  of  the  most  posterior  ganglia.  The  difference 
in  the  number  of  the  abdominal  ganglia  in  the  two  sexes  of  the 
flea  shows,  therefore,  that  in  the  female  the  concentration  has 
gone  one  step  farther  than  in  the  male,  since  only  six  abdominal 
ganglia  remain  free  in  the  female,  but  seven  in  the  male.  The 
nervous  system  of  the  female  has  therefore  reached  one  stage  in 
evolution  higher  in  the  female  than  in  the  male.  Similar 
differences  between  the  sexes  are  known  to  occur  also  in  other 
insects,  especially  in  the  Hymenoptera  (the  order  which  includes 
the  bees,  ants,  and  wasps),  an  order  in  which  the  superiority  in 
intelligence  and  in  the  social  virtues  of  the  female  over  the  male 
is  very  marked. 

Besides  the  difference  in  the  number  of  ganglia,  the  nervous 
systems  of  the  male  and  female  flea  differ  also  in  the  arrangement 
of  the  nerve-stems  given  off  from  the  hindmost  ganglion-mass.  In 
the  male  two  stout  nerves  are  given  off,  which  run  on  either  side 
of  the  "  corkscrew-organ''  (see  p.  454),  and  are  distributed  mainly 
to  the  powerful  muscles  which  work  the  penis.  In  the  female, 
however,  three  pairs  of  moderately  stout  nerves  are  given  off, 
which  go  to  the  genitalia,  but  I  have  not  been  able  to  trace  their 
exact  distribution. 

Comparing  the  two  figures,  it  is  seen  that  the  male  and  female 
nervous  systems  are  approximately  of  the  same  absolute  length. 
Since,  however,  the  female  flea  is  considerably  larger  than  the 
male,  the  nervous  system  of  the  female  is  relatively  much 
the  shorter,  and  does  not  extend  so  far  into  the  abdomen  as  that 
of  the  male.  Consequently  the  nervous  system  of  the  male  is 
the  easier  to  dissect  out. 

As  regards  minuter  details,  the  nerve-ganglia  are  seen  to 
contain  a  number  of  nuclei,  representing  the  ganglion-cells, 
which  have  a  bilaterally  symmetrical  arrangement,  showing  that 
each  ganglion-mass  is  a  fusion  of  a  pair  of  ganglia.  The  nerves 
which  come  off  from  the  ganglia  right  and  left  contain  small, 
elongated  nuclei,  which  are  the  nuclei  of  the  connective  tissue- 
sheaths  of  the  nerves.  The  connectives  running  between  the 
successive  abdominal  ganglia  contain  no  nuclei,  but  the  stout 
connectives  passing  forwards  from  the  metathoracic  ganglion- 
mass  contain  elongated  nuclei  similar  to  those  of  the  peripheral 
nerves. 


450       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

II.   The  Salivary  Glands. 

Having  occasion  to  dissect  some  flea-larvae,  I  was  struck  by 
the  fact  that  the  salivary  glands  of  the  larva  differ  greatly,  both 
in  size  and  in  complication  of  parts,  from  those  of  the  adult  flea. 
I  will  begin  with  the  adult,  in  which  the  glands  are  both  smaller 
and  simpler  in  structure. 

In  the  adult  flea  the  salivary  glands  lie  in  the  abdomen,  right 
and  left  of  the  stomach,  in  the  form  of  two  tiny  pouches  on  each 
side  (PI.  27,  B  and  C).  Each  pouch  consists  of  large  glandular 
cells,  which  tend  to  stain  very  opaquely  and  have  large  nuclei. 
The  two  pouches  of  each  side  give  off  each  a  short  duct,  and  these 
two  ducts  unite  into  a  long  duct  running  forwards  on  the  side  of 
the  body  to  the  anterior  thoracic  region,  where  the  two  ducts  from 
the  two  sides  of  the  body  unite  into  a  common  salivary  duct,  which 
runs  forwards  to  open,  doubtless,  into  the  hypopharynx,  as  in 
other  insects.  The  paired  salivary  ducts  have  a  very  character- 
istic appearance,  being  lined  by  a  chitinous  cuticle  which  shows 
internally  a  system  of  rather  irregular  transverse  thickenings. 
This  appearance  is  seen  from  the  point  where  the  ducts  issue 
from  the  glands  up  to  a  short  distance  from  the  spot  where  the 
paired  ducts  unite  to  form  the  common  salivary,  duct ;  the 
structure  of  the  ducts  recalls  to  some  extent  that  of  a  tracheal 
tube,  but  the  transverse  thickenings  are  not  so  perfectly  regular 
as  in  the  tracheae.  At  the  point  of  union  of  the  right  and  left 
salivary  ducts,  however,  there  is  a  Y-piece  in  which  the  duct 
diminishes  in  calibre  to  about  half,  and  has  no  transverse 
thickenings.  External  to  the  chitinous  lining,  the  duct  is 
covered  by  a  delicate  layer  of  flat  epithelium,  which  does  not 
show  distinct  cell-outlines,  but  has  the  appearance  of  a  plas- 
modial  or  syncytial  layer  of  protoplasm  with  scattered  nuclei. 

The  salivary  gland  of  the  adult  flea,  on  account  of  its  small 
size,  is  not  so  easy  to  dissect  out ;  the  glands  of  the  female  are 
slightly  larger  than  those  of  the  male.  On  the  other  hand,  the 
salivary  glands  of  the  larva,  which  are  plainly  visible  through 
the  body-wall  of  the  living  insect,  are  very  easily  dissected  out. 
All  that  is  necessary  is  to  decapitate  the  larva  in  such  a  way  as 
to  cut  off  the  first  or  first  two  thoracic  segments,  together  with 
the  head,  and  then  to  press  with  the  flat  of  a  dissecting  needle 
gently  along  the  body  from  behind  forwards,  so  as  to  squeeze  out 


THE    RAT-FLEA,    CERATOPHYLLUS  FASCIATUS    BOSC.  451 

the  contents  of  the  body-cavity  through  the  cut  end  of  the  trunk. 
The  salivary  glands  sometimes  come  out  as  soon  as  the  flea  is 
decapitated,  without  any  such  pressure,  and  it  is  easy  to  get 
them  on  to  a  cover-slip  and  fix  them. 

Almost  the  only  point  in  which  the  larval  glands  (PI.  27,  A) 
resemble  those  of  the  adult  is  in  the  characteristic  structure  of 
the  duct,  which  can  be  recognised  immediately.  Passing  back 
along  the  duct  (d.),  we  come  to  a  thin- walled  dilated  sac  or 
reservoir  (r.),  quite  absent  in  the  adult.  Behind  the  duct  a 
tubule  begins,  composed  of  lightly  staining  glandular  cells.  After 
a  short  course  this  tubule  becomes  continuous  with  the  gland 
proper,  which  is  composed  of  darkly  staining  glandular  cells,  and 
branches  out  into  three  lobes  or  diverticula,  two  of  which  run 
forward  (l.a.1,  l.a.2)  and  one  backward  (l.p.)  alongside  of  the 
digestive  tract.  All  this  arrangement  of  duct,  reservoir,  and 
gland  is,  of  course,  duplicated  on  each  side  of  the  body,  right 
and  left. 

Accompanying  the  larval  salivary  gland  are  two  elongated 
pads  or  cushions  of  fat-body,  which  are  very  difficult  to  separate 
from  the  gland  without  damaging  the  glandular  lobes.  In  the 
hinder  of  these  pads  of  fat  I  found  in  many  fleas  a  body  which 
looked  exceedingly  like  a  parasitic  cyst,  for  which  I  mistook  it  at 
first.  Specimens  mounted  whole  showed  the  "  cyst  "  to  be  com- 
posed of  large  cells  in  the  interior,  showing  a. tendency  in  the 
more  advanced  specimens  to  arrangement  in  longitudinal  rows, 
and  enveloped  by  a  layer  of  flat  epithelium  at  the  surface.  At 
its  hinder  end  the  "  cyst "  is  prolonged  into  a  delicate  cord  of  cells 
which  could  be  traced  in  some  specimens  a  long  way  back. 
Further  investigation  showed,  however,  that  when  this  "  cyst " 
was  present  on  one  side  of  the  body  it  was  also  present  on  the 
other  side  in  exactly  the  same  degree  of  development ;  and  further, 
that  when  the  "cysts"  were  absent  in  the  fat-body  on  the  level 
of  the  salivary  glands,  they  were  to  be  found  in  other  pads  of  fat- 
body  situated  farther  back,  on  the  level  of  the  intestine  right 
and  left.  Hence  it  was  obvious  that  the  supposed  parasitic  cysts 
were  simply  the  genital  rudiments,  situated  farther  forward  in 
the  larvae  of  one  sex  than  in  the  other.  Whether  it  is  the  male, 
or  the  female,  in  which  they  are  situated  farther  forward,  I 
cannot  say. 

The  striking  differences  between  the  larval  and  adult  flea  in 


452       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

respect  to  the  salivary  glands  must  be  related  to  the  difference  in 
their  habits.  The  adult  flea,  I  need  not  say,  is  a  blood-sucker, 
and  in  blood-sucking  insects  generally  the  function  of  the  salivary 
glands  is  believed  to  be  that  of  producing  a  secretion  which  is 
mixed  with  the  ingested  blood  and  prevents  it  from  coagulating. 
Incidentally  the  salivary  glands  of  the  adult  flea,  if  crushed  and 
examined,  can  be  seen  to  contain  many  yeast-like  bodies  of  several 
kinds,  and  it  is  supposed  that  it  is  these  microbes  which  are 
responsible  for  the  local  irritation  and  itching  caused  by  the 
puncture  of  the  flea's  proboscis.  The  flea-larva,  on  the  other 
hand,  is  more  or  less  omnivorous,  but  appears  to  feed  principally 
on  the  faeces  of  the  rat,  as  well  as  dirt  and  debris  of  all  kinds. 
Consequently  its  salivary  glands  have  a  function  in  the  insect's 
economy  entirely  different  from  that  of  the  adult  flea,  assisting 
probably  in  the  digestion  of  the  food,  and  their  larger  size  in  the 
larva  indicates  a  greater  secretive  activity  than  in  the  adult. 

III.    The  Male  Reproductive  Organs. 

The  genitalia  of  the  male  flea  exhibit  a  singular  complication 
of  parts  and  of  their  arrangement,  but  are  nevertheless  very  easy 
to  dissect  out,  and  with  a  little  care  the  entire  reproductive  system, 
from  testes  to  penis,  can  be  mounted  as  one  preparation,  in  which 
every  detail  can  be  studied  with  the  exception  of  those  minuter 
points  of  structure  which  require  sections  for  exact  study. 

A  general  sketch  of  the  various  parts  is  given  in  Plate  28. 
All  the  details  of  this  sketch  have  been  drawn  from  mounted 
dissections  with  the  camera  lucida  at  a  magnification  of  150 
diameters,  reduced  in  the  reproduction  by  one-half.  At  the  same 
time  the  relation  of  the  various  parts  and  their  relative  position 
in  the  body  has  been  checked  by  sketches  of  the  whole  system, 
both  of  such  parts  of  it  as  can  be  seen  through  the  body-wall  of 
the  flea  without  dissection,  and  also  as  it  is  seen  when  the  abdomen 
of  the  flea  is  freshly  opened  with  the  least  possible  disturbance  of 
the  organs. 

Most  anteriorly  are  situated  the  two  conspicuous  testes  (T  ,  T.) 
with  their  ducts  coming  off  from  them,  and  shaped  somewhat  like 
a  pear  would  be  if  the  stalk  (the  duct)  came  off  from  its  thicker 
end.  The  testes  lie  dorsal  to  the  stomach,  but  vary  to  some 
extent  both  in  size  and  arrangement.  When  the  testes  are  of 
large  size,  as  in  the  younger  males,  they  lie  one  in  front  of  the 


THE    RAT-FLEA,    CERATOPHYLLUS  FASCIATUS   BOSC.  453 

other,  and  then  the  duct  of  the  testis  lying  more  anteriorly  runs 
straight  back,  while  that  of  the  testis  situated  more  posteriorly  is 
coiled.  When  the  testes  are  smaller,  as  in  the  older,  more 
exhausted  males,  they  lie  side  by  side  and  their  ducts  run  straight 
back. 

When  the  testis  is  examined  it  is  seen  at  once  to  consist  of  two 
parts,  a  dilated  bladder-like  portion  of  ovoid  shape,  at  the  base  of 
which  is  a  coiled  tubular  portion.  The  bladder-like  portion 
appears  to  be  the  testis  proper  (T  ),  while  the  coiled  tubular 
portion  (ep.1)  recalls  the  structure  in  the  human  testis  known  as 
the  epididymis,  and  may  be  known  conveniently  by  this  designa- 
tion. In  one  of  my  dissections  I  succeeded  in  uncoiling  the 
epididymis  forcibly,  by  pulling  on  the  duct  (ep.2).  It  was  then 
seen  that  the  epididymis  is  a  thin-walled  tube,  tilled  with  ripe 
spermatozoa  ;  consequently,  from  the  point  of  view  of  function, 
the  epididymis  represents  a  vesicula  seminalis,  that  is  to  say  a 
receptacle  for  the  storage  of  ripe  sperm.* 

The  calibre  of  the  tubular  epididymis  narrows  rapidly  as  it 
passes  on  into  the  duct,  which  may  be  called  here,  as  in  other 
animals,  the  vas  deferens.  The  right  and  left  vasa  deferentia  (v.d.1, 
v.d.2)  run  back  a  little  way  and  join  to  form  the  common  vas 
deferens  (v.d.3),  but  it  can  be  seen  very  easily  that  the  union  of 
the  paired  vasa  deferentia  is  merely  external  and  not  internal, 
since  the  lumina,  or  internal  cavities,  of  the  two  ducts  remain 
quite  distinct. 

The  common  vas  deferens  runs  to  a  set  of  glandular  structures 
which  I  regard  as  corresponding  to  a  prostate  gland,  and  consist- 
ing altogether  of  four  blind  tubular  diverticula ;  a  median  pair  of 
short  tubules,  which  maybe  termed  the  median  prostates  (r.m.p.), 
and  a  much  longer  pair  of  lateral  tubules,  which  may  be  called 
the  lateral  prostates  (r.l.p.).  The  two  median  prostates  are  in 
close  contact,  but  their  cavities  are  quite  distinct  and  independent. 
The  walls  of  the  tubules  are  composed  of  a  single  layer  of 
glandular  epithelial  cells  of  small  size,  which  show  in  surface  view 
very  distinct  polygonal  outlines  (PI.  30,  B).     The  tubules  contain 

*  The  structure  of  the  testis  was  not  quite  correctly  described  in  our 
monograph  on  the  development  of  T.  leicisi  (Minchin  and  Thomson,  I.e.). 
When    that   was  written   I   had   not  seen   the   epididymis   uncoiled,  and 
regarded   the    dilated    bladder-like   portion   of    the    testis   as    a   vesicula 
seminalis. 


454       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

a  cavity,  relatively  spacious,  in  which  I  have  never  seen  any 
spermatozoa ;  they  cannot  therefore  be  regarded  as  vesiculae 
seminales,  but  probably  have  a  purely  secretive  function. 

The  common  vas  deferens  runs  towards  the  median  prostates 
and  then  loops  round  them  in  a  peculiar  manner,  running  in  the 
valley  between  the  two  contiguous  median  prostates.  Just  after 
the  two  still  separate  ducts,  which  form  by  their  apposition  the 
common  vas  deferens,  have  passed  the  prostates,  there  is  a  slight 
dilatation  of  the  ducts  into  which  the  prostatic  tubules  open,  but 
quite  separately ;  that  is  to  say,  the  left  median  and  left  lateral 
prostate  open  into  the  left  half,  the  right  median  and  right 
lateral  prostate  into  the  right  half,  of  the  common  vas  deferens. 

The  common  vas  deferens,  after  receiving  the  openings  of  the 
prostates,  runs  on  towards  the  penis  as  a  duct  which  may  be 
termed,  as  in  other  animals,  the  ductus  ejaculatorius  (d.ej.). 
Like  the  common  vas  deferens,  however,  the  ductus  ejaculatorius 
is  a  double-barrelled  structure,  consisting  of  two  ducts  in  close 
contiguity,  but  with  distinct  internal  cavities. 

At  the  point  where  the  ductus  ejaculatorius  enters  the  penis 
there  is  a  most  singular  complication  of  structure.  The  proximal 
end  of  the  penis  is  prolonged  into  a  spirally  coiled  organ  which, 
for  lack  of  a  better  name,*  I  propose  to  call  the  "  corkscrew- 
organ,"  since  it  resembles  in  form  a  corkscrew,  or  a  spiral  drill  or 
borer,  of  about  four  turns  (c.s.o.).  The  ductus  ejaculatorius  runs 
straight  to  the  base  of  the  corkscrew  and  through  its  axis  ;  at 
the  point  where  it  enters  the  axis  of  the  corkscrew  the  ductus 
ejaculatorius  can  be  seen  very  plainly  to  be  still  double  ;  it  is 
difficult  to  make  out  clearly  what  happens  in  the  axis  of  the 
corkscrew,  but  when  this  structure  is  viewed  from  the  top,  it  is 
seen  equally  plainly  that  the  duct  emerges  from  the  axis  as  a 
single  duct,  no  longer  double-barrelled.  It  is  evident,  therefore, 
that  the  two  ducts  that  come  from  the  testes,  maintaining  their 
individuality  and  distinctness  up  to  this  point,  become  confluent 
at  some  spot  in  the  axis  of  the  screw.     This  single  duct,  the  duct 

*  I  regret  to  say  that  my  meagre  acquaintance,  which  I  have  not  had  the 
leisure  to  extend,  with  the  vast  and  scattered  literature  relating  to  the 
anatomical  structure  of  insects,  is  inadequate  to  permit  me  to  state  whether 
this  or  similar  organs  in  other  insects  have  been  studied  in  detail  and 
whether  there  exists  already  a  special  technical  term  for  the  structure 
which  I  term  here  in  a  purely  descriptive  manner  "  corkscrew-organ." 


THE    RAT-FLEA,    CBRATOPHTLLUS  FASCIATUS    BOSC.  455 


"which  runs  the  whole  length  of  the  penis,  may  be  called  dis- 
tinctively the  urethral  duct  (d.).*  The  exact  point  at  which  it 
begins  in  the  axis  requires  to  be  determined  by  sections. 

The  urethral  duct  emerges  from  the  axis  of  the  corkscrew  at 
its  apex  and  there  turns  and  runs  outwards  round  the  outer  edge 
of  the  spiral  of  the  corkscrew,  enclosed  between  two  chitinised 
bars,  or  more  correctly  thickenings  of  the  wrall  of  the  duct. 
These  chitinous  thickenings  are  best  seen  in  unstained  prepara- 
tions of  the  penis  (PI.  29).  The  chitin  on  the  inner  side  of  the 
duct  (i.e.  on  the  side  of  it  turned  towards  the  axis  of  the  spiral) 
is  the  thicker  and  stronger  of  the  two,  but  is  only  continued 
from  the  base  over  about  three  turns  of  the  spiral,  while  the 
thinner  chitinous  bar  on  the  outer  side  of  the  duct  is  continued 
for  nearly  a  whole  turn  more. 

The  structure  of  the  corkscrew -organ  is  difficult  to  make  out 
in  full  detail  without  sections,  but  if  a  portion  of  the  spiral  be 
carefully  examined,  the  following  points  can  be  seen  in  dissections 
of  the  whole  apparatus  stained  and  mounted  (PI.  30,  A).  At  the 
extreme  outer  edge  of  the  spiral  is  seen  the  narrow  urethral 
duct  (d.)  with  its  chitinous  thickenings  on  the  inner  and  outer 
side.  Running  from  the  axial  region,  which  can  also  be  seen  in 
the  unstained  preparations  to  have  a  chitinous  support  (ax.),  is  a 
superficial  layer  of  radiating  striated  muscles,  which  run  across 
from  the  axis  centrally  to  the  duct  peripherally;  this  layer  can  be 
focused  without  difficulty.  At  a  deeper  focus,  below  the  radiating 
muscles,  two  structures  can  be  made  out  lying  between  the  axis 
and  the  duct ;  close  to  the  axis  and  apparently  attached  to  it,  is 
a  spiral  muscle  (sp.m.)  composed  also  of  striated  muscular  fibres ; 
and  between  the  spiral  muscle  and  the  urethral  duct  is  a  cushion 
of  cells  which  appear  to  be  glandular  in  appearance,  but  sections 
would  be  necessary  to  determine  their  precise  histological  nature. 
These  various  structures  can  be  seen  best  in  the  lowest  coil  of  the 
oorkscrew ;  they  are  depicted  in  Plate  30,  A,  but  it  is  difficult  to 

*  If  a  dissection  of  the  male  reproductive  organs  be  treated  with  caustic 
potash,  everything  up  to  the  base  of  the  corkscrew,  that  is  to  say  the  vasa 
deferentia,  prostates  and  ductus  ejaculatorius,  dissolve  away,  but  the 
urethral  duct  issuing  from  the  apex  of  the  corkscrew  remains  very  distinct 
and  this  is,  as  a  matter  of  fact,  the  best  way  to  study  its  course.  It  would 
appear,  therefore,  as  if  the  urethral  duct  is  distinguished  from  the  other 
ducts  by  the  possession  of  a  chitinous  lining,  and  therefore  represents,  pro- 
bably, an  ingrowth  of  the  outer  integument  in  origin. 


456       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    AK ATOMY    OF 

combine  clearly  in   one    sketch    things    seen  in  the  microscopic 
preparation  at  different  foci. 

Seen  in  life,  that  is  to  say  in  a  freshly  dissected  flea,  the  cork- 
screw-organ is  usually  performing  peculiar  pulsating  movements, 
which  remind  one  to  some  extent  of  the  movements  of  the  hair- 
spring of  a  watch,  with  the  difference  that  the  hairspring  lies  in. 
one  plane,  while  in  the  organ  of  the  flea  the  axis  of  the  spiral  i& 
prolonged  vertically  so  that  a  form  like  a  corkscrew  results.  It 
is  seen  that  in  the  living  condition  the  corkscrew  becomes  alter- 
nately first  longer  and  narrower  and  then  shorter  and  broader. 
The  elongation  and  narrowing  of  the  corkscrew  is  doubtless 
brought  about  by  the  contraction  of  the  radiating  superficial 
muscles  ;  these  in  their  turn  are  antagonised  by  the  spiral  muscle, 
which  by  its  contraction  would  tend  naturally  to  make  the  cork- 
screw shorter  and  broader. 

As  to  the  function  of  corkscrew- organ,  I  can  only  offer  the 
suggestion  that  it  may  act  as  a  sort  of  sperm -pump.  The  move- 
ments seen  in  the  freshly  dissected  flea  may  perhaps  become  more 
active  and  regularly  rhythmical  during  the  act  of  copulation, 
and  serve  to  pump  the  sperm  on  from  the  ductus  ejaculatorius 
and  vasa  deferentia  into  the  penis.  This  is,  of  course,  a  mere 
conjecture  from  the  observed  facts  of  its  structure  and  activity. 
If,  on  the  other  hand,  the  cushion  of  cells  between  the  spiral 
muscle  and  the  duct  be  glandular  in  nature,  the  organ  as  a 
whole  must  have  other  functions  in  addition  to  that  of  acting 
as  a  pump. 

The  penis  is  an  organ  of  complicated  structure,  which  I  will 
deal  with  briefly  ;  PI.  29  shows  what  I  have  been  able  to  make 
out  in  preparations  mounted  unstained,  or  further  cleared  with 
potash  before  mounting.  The  penis  (P.),  which  is  very  large  in 
proportion  to  the  size  of  the  insect,  is  made  up  of  strong  thick 
bars  of  chitin.  It  is  worked  mainly  by  strong  protractor  and 
retractor  muscles  attached  to  a  broad  bar  of  chitin  (b1),  which  is 
a  prolongation  of  the  dorsal  integument  at  the  right  and  left 
margins  of  the  pygidium.  The  median  retractor  muscles  (m.r.) 
are  attached  distally  to  a  prolongation  of  the  dorsal  side  of  the 
penis,  and  the  lateral  retractors  (l.r.m.)  are  attached  to  a  bar  (b2) 
which  arises  from  the  ventral  side  of  the  penis;  there  are  two  such 
bars,  right  and  left,  diverging  from  one  another  like  aV;  it  is 
clearly  impossible  that  the  penis  could  be  protruded  farther  from 


THE    RAT- FLEA,    CERATOPHYLLVS  FASCIA  TVS    BOSC.  457 

the  body  than  the  point  of  insertion  of  these  bars  (b2).  I  think 
it  probable  that  there  are  more  muscles  attached  to  b2  than 
are  seen  in  my  figure,  but  have  become  torn  away  in  the  dis- 
section. Both  b1  and  b2  can  be  seen  clearly  through  the  body- 
wall  in  the  uninjured  flea.  From  the  thick  beam  of  chitin 
which  forms  the  dorsal  part  of  the  penis  a  lateral  muscle  (l.m.) 
omes  off,  which  is  probably  attached  distally  to  the  integument. 

In  one  of  my  preparations  treated  with  potash,  spermatozoa* 
could  be  seen  very  plainly  in  the  interior  of  the  urethral  duct, 
and  they  have  been  put  into  the  figure  on  PI.  29  in  order  to 
show  the  course  of  the  duct.  The  spermatozoa  (sp.z.)  begin  in  the 
lowest  coil  of  the  corkscrew -organ,  where  they  show  a  peculiar 
festoon-like  arrangement.  As  the  duct  passes  into  the  body  of 
the  penis,  the  spermatozoa  take  on  an  arrangement  in  wavy 
bundles  and  the  calibre  of  the  duct  widens  considerably,  and 
at  the  same  time  the  spermatozoa  show  that  the  duct  crosses  over 
the  chitinous  bar  which  forms  the  inner  boundary  of  the  duct  in 
the  corkscrew-organ,  and  which  has  now  become  very  much 
thinner  and  more  delicate,  passing  on  to  be  merged  into  a  much 
thicker  bar  on  the  ventral  side  of  the  penis.  Just  a  little 
in  front  of  the  middle  region  of  the  penis  the  spermatozoa  are 
heaped  up  in  a  way  that  shows  the  duct  to  have  become  greatly 
enlarged  in  calibre,  but  behind  this  point  the  spermatozoa  dis- 
appear altogether.  In  stained  preparations  it  can  be  seen  that 
the  penis  has  a  superficial  layer  of  muscles  which  appear  to  have 
a  criss-cross  arrangement,  and  lie  on  the  wall  of  the  widened 
spermatic  duct,  but  they  have  not  been  put  into  the  drawing,  as 
their  exact  position  and  arrangement  are  difficult  to  make  out 
clearly.  The  contraction  of  the  superficial  muscles  would  doubt- 
less have  the  effect  of  contracting  the  lumen  of  the  penis  and 
ejecting  the  sperm. 

Such  are  the  main  points  of  the  structure  of  this  very  com- 
licated  apparatus,  so  far  as  I  have  been  able  to  make  them  out ; 
but  I  think  it  probable  that  there  are  more  minutiae  to  be 
described,  especially  with  regard  to  the  structural  details  of  the 
penis  and  "  corkscrew-organ." 

IV.    The  Female  Reproductive  System. 

As  regards  the  primary  sexual  organs  of  the  female  sex,  they 
are  of  the   usual  insectan  type,  and  can  be  dealt  with  briefly. 
Journ.  Q.  M.  C,  Series  II. — No  76.  32 


458       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

There  is  a  pair  of  ovaries,  lying  symmetrically  right  and  left  in 
the  abdomen  dorsal  to  the  stomach.  Each  ovary  consists  of  a 
number  of  ovarian  tubes  or  ovarioles  ;  usually  four  on  each  side, 
but  in  one  of  my  mounted  preparations  there  are  five  ovarioles  in 
each  ovary.  The  ovarioles  are  of  the  simplest  type,  composed  of 
successive  egg-chambers,  increasing  progressively  in  size,  without 
special  yolk-chambers.  The  ovarioles  of  each  side  unite  into  a 
short  paired  oviduct,  and  the  paired  oviducts  of  the  two  sides 
unite  into  a  median  unpaired  oviduct,  in  which,  probably,  the 
ovum  is  fertilised  and  subsequently  becomes  invested  by  a  shell. 

In  addition  to  the  ovaries  and  oviducts,  which  are  very  easy 
to  dissect  out,  there  lies,  ventral  to  the  rectum,  an  organ  found 
in  all  fertile  female  insects,  the  receptaculum  seminis,  into  which 
the    sperm  is  received  at  copulation    and  stored  up  in  order  to 
fertilise  the  eggs  as  required.     The   receptaculum  and  its  duct 
are  by  no  means  difficult  to  dissect  out  and  mount,  and  make  a 
singularly    beautiful    and    fascinating    microscopic    preparation 
(PI.  31).    The  duct  is  coiled  up  into  a  veritable  labyrinth,  and  the 
sole  difficulty  in  the  dissection  is  to  uncoil  it  without  breaking  it. 
The  receptaculum   itself  (R.S.)  is  a  chitinous  capsule  with  a 
brown,  delicately  sculptured,  semi-transparent  wall,  and  a  peculiar 
form.     The  main  portion  of  the  capsule,  that  portion  from  which 
the  duct  arises,  is  roughly  spherical  in  form.    At  one  point,  which 
is  distant  from  the  origin  of  the  duct  by  about  one-third  of  the 
circumference  of  the  main  chamber,  an  outgrowth  or  diverticulum 
arises,   forming  a    second    chamber,   which  is   horn -shaped,  and 
bends  round  the  main  chamber.     The   horn-shaped    chamber   is 
connected,  on  its  concave  side,  to  the  main  chamber  by  a  sheet  of 
striated  muscle  (m.r.s.).     The  contraction  of  these  muscle-fibres 
must  clearly  have   the  effect  of  approximating  the  horn-shaped 
chamber   to   the    main   chamber,   and   at  the    point  where   the 
horn-shaped  chamber  arises  from  the  main  chamber  there  is  a 
rim  of  chitin  which  appears  to  be  softer  than  the  rest  of  the  wall, 
forming    a   weaker    spot    which    apparently    serves   as   a    hinge, 
allowing  the  horn-shaped  chamber  to  be  moved  slightly ;  it  is  at 
this  spot  that  artificial  deformations  of  the  wall  of  the  capsule 
are   often  caused    as  the  result   of   slight    shrinkage  when    the 
receptaculum  is  mounted  in  Canada  balsam.     The  receptaculum 
is  usually  packed  with  spermatozoa,  which  can  be  seen  through 
the  wall  of  the  capsule,  but  better  still  if  the  capsule  be  burst 


TIIE    RAT-FLEA,    CERAT0PHTLLU8  FASCIATUS   BOSC.  459 

open  by  pressure  under  a  cover-glass  when  freshly  dissected  out. 
In  one  of  my  specimens  the  receptaculum  is  empty  and  contains 
no  spermatozoa  ;  this  specimen  is  also  the  only  one  I  have 
succeeded  in  mounting  in  Canada  balsam  without  any  shrinkage 
taking  place  in  the  hinge-region.  This  virgin  receptaculum  also 
shows  some  structures  in  the  interior,  the  nature  of  which  I  have 
not  been  able  to  make  out  clearly,  but  which  look  rather  like 
prolongations  of  the  duct  into  the  interior  of  the  main  chamber. 
Sections  would  be  necessary,  however,  to  determine  the  nature  of 
these  internal  arrangements,  which  are  not  visible  in  any  of  my 
specimens  that  are  filled  with  spermatozoa. 

The  duct  of  the  receptaculum  (d.,  d.,  d.)  is  of  extraordinary 
length,  and  just  where  it  arises  from  the  main  chamber  it  is 
surrounded  by  a  cushion  of  deeply  staining,  closely  packed  cells 
of  glandular  appearance  (gl.c.),  each  shaped  somewhat  like  an 
Indian  club.  The  duct  itself  has  an  irternal  chitinous  lining 
secreted  by  an  external  epithelial  layer,  which  is  shallow  and 
contains  small  nuclei  in  great  number  but  shows  no  distinct 
cell-outlines.  At  its  proximal  end,  immediately  after  it  comes 
through  the  glandular  cushion  already  mentioned,  the  duct  is 
surrounded  by  a  great  number  of  rounded  cells  (gl.),  which  have 
clear,  lightly  staining  contents,  and  present  also  a  glandular 
appearance.  The  rounded  cells  are  thickly  clustered  round  the 
proximal  end  of  the  duct,  but  as  the  duct  is  followed  along  in 
a  distal  direction  they  diminish  in  number  and  gradually  thin 
out  until,  about  half-way  along  the  duct,  they  disappear 
altogether,  and  the  distal  half  of  the  duct  consists  only  of  the 
chitinous  lining  and  the  epithelium  with  small  nuclei. 

As  the  duct  approaches  its  termination  it  shows  some  peculiar 
complications,  forming  what  I  propose  to  call  the  terminal  organ 
(T.O.).  First  of  all  there  is  a  feeble  imitation  of  the  corkscrew- 
organ  in  the  shape  of  a  broad  expanded  plate,  apparently 
chitinous,  on  one  side  of  the  duct,  which  performs  a  spiral 
twist  of  one  complete  turn.  The  spiral  portion  passes  on  into 
a  short  length  of  the  duct,  which  has  on  one  side  a  thickening 
of  the  chitin  to  form  a  strong  bar  (c.b.),  bent  like  a  bow,  which 
is  strung,  so  to  speak,  by  a  strong  muscle  of  four  or  five  fibres 
(m.t.o.).  I  have  not  been  able  to  determine  exactly  by  dissection 
where  the  duct  finally  opens,  whether  into  the  unpaired  oviduct 
or    into    a    terminal    genital    vestibule   or    vulva ;    sections,    or 


460       E.    A.    MINCHIN    ON    SOME    DETAILS    IN    THE    ANATOMY    OF 

perhaps   specimens   cleared   in    potash,    would   he    necessary   to 
determine  this  point. 

The  spermatozoa  live  a  very  long  time,  as  is  well  known,  in 
the  receptaculum,  and  are  used  up  gradually  to  fertilise  the  eggs 
as  they  are  laid.  In  the  queen-bee  it  is  known  that  the  insect 
lays  fertile  eggs  for  at  least  three  years,  and  in  some  other 
insects  this  length  of  time  may  be  exceeded  by  a  considerable 
amount.  The  muscles  seen  in  connection  with  the  receptaculum 
and  its  duct  may  be  connected  with  the  function  of  passing  out 
the  spermatozoa.  A  contraction  of  the  muscle  connecting  the 
horn-shaped  chamber  of  the  receptaculum  with  the  main  chamber 
would  probably  force  some  spermatozoa  out  into  the  duct.  On 
the  other  hand,  a  contraction  of  the  "  bowstring  "  muscle  of  the 
terminal  organ  would  bend  the  "  bow,"  and  so  occlude  the  duct, 
preventing  anything  from  passing  out.  There  does  not  seem  to 
be  any  apparatus  for  forcing  the  spermatozoa  up  the  duct  and 
into  the  receptaculum,  but  this  is  effected  probably  during 
copulation  by  the  male  intromittent  organ — possibly  by  the 
problematic  "  corkscrew-organ."  The  spermatozoa  in  the  recep- 
taculum must  be  kept  alive  a  long  time,  and  may  be  nourished 
by  the  secretion  of  the  glandular  cushion  round  the  origin  of 
the  duct,  while  the  rounded  gland-cells  on  the  duct  may  perform 
some  similar  function  for  the  spermatozoa  during  their  passage 
down  the  labyrinthine  duct,  the  great  length  of  which  is  difficult 
to  explain  in  a  plausible  manner.  All  these  suggestions  have, 
however,  only  the  value  of  more  or  less  probable  surmises. 

In  the  tsetse-fly  the  receptaculum  is  a  paired  organ,  and  in 
the  gnat  there  are  three  receptacula,  one  median  and  two 
paired.  In  that  of  the  flea  there  is  no  sign  of  any  double 
structure. 

V.  Muscle-cells  of  Stellate  Form  in  the  Oesophagus  of  the  Flea. 

In  some  of  our  smear-preparations  of  teased  flea -stomachs, 
made  in  the  course  of  our  investigation  into  the  development  of 
Trypanosoma  lewisi,  there  were  to  be  found  occasionally  specimens 
of  the  flea's  oesophagus,  which  adhered  to  the  cover-glass  after  it 
had  been  fixed  with  Maier's  sublimate-alcohol  mixture  and 
stained  by  Heidenhain's  iron-haematoxylin  method.  In  such 
preparations  it  is  easily  seen  that  the  oesophagus  has  a  beautiful 


THE    RAT-FLEA,    CBRATOPHYLLUS  FASCIATUS   BOSC  -tG  1 


and  very  delicate  layer  of  muscular  tissue,  in  the  form  of  a 
network  (PI.  32,  A,  B  and  C).  The  individual  muscle-cells 
are  branched  like  ganglion -cells,  and  their  processes  anastomose 
to  form  the  network.  Some  nodes  of  the  network  are  formed 
merely  by  the  union  of  two  or  three  such  processes,  while  other 
nodes  are  formed  by  the  body  of  the  cell,  and  contain  the 
cytoplasmic  cell-body  with  a  nucleus.  The  processes  themselves 
are  transversely  striated,  and  form  the  actual  muscle-fibres.  It 
can  be  seen  that  at  a  cellular  node  of  the  network  the  striated 
fibres  pass  right  through  the  body  of  the  cell  and  come  out 
on  the  other  side,  their  striation  and  individuality  becoming 
slightly  less  distinct  in  their  passage  through  the  cytoplasm  of 
the  cell. 

Remembering  that  I  had  seen  muscle-cells  of  a  somewhat 
similar  type  in  the  "  crop  "  or  "  sucking  stomach  "  of  the  tsetse- 
fly,  an  organ  which  is  morphologically  a  diverticulum  of  the 
oesophagus,  I  made  a  preparation  of  the  crop  of  a  common 
house-fly  and  found  a  musculature  of  a  very  similar  type 
(PI.  32,  D,  E).  The  main  differences  are,  first,  that  the  cells 
are  on  a  much  larger  scale  of  size,  requiring  lower  powers  of  the 
microscope  for  their  study ;  secondly,  that  the  muscular  network 
has  a  definitely  rectangular  arrangement,  those  fibres  which  run 
in  certain  directions  being  considerably  thickened,  and  connected 
with  one  another  by  delicate  fibres  running  across  at  right 
angles.  In  some  parts  the  thickening  of  these  longitudinal  fibres 
is  much  more  marked  than  in  others.  All  the  fibres,  even 
the  thinnest,  show  the  characteristic  transverse  striation  very 
distinctly. 

The  resemblance  of  the  muscular  network  in  the  two  cases 
raises  some  interesting  points  of  phylogeny.  In  the  first  place, 
it  should  be  noted  that  a  contractile  network  is  the  most 
efficient  arrangement  for  the  contraction  of  a  bladder,  since  it 
gives  an  even  contraction  in  all  directions.  The  muscles  of  the 
human  urinary  bladder  are  also  arranged  in  a  network,  but  on  a 
much  larger  scale  than  those  described  here,  since  the  strands  of 
the  network  are  not  outgrowths  of  individual  cells,  but  are  made 
up  of  thick  bundles  of  contractile  cells.  It  is  therefore  not 
surprising  to  find  a  network  in  the  contractile  elements  of  an 
organ  such  as  the  crop  of  the  house-fly.  On  the  other  hand,  it 
is  rather  remarkable  to  find  it  in  the  oesophagus  of  the  flea. 


462       E.    A.    MINCHIN    ON    SOME    DETAILS    JN    THE    ANATOMY    OF 

Entomologists  are  generally  agreed  in  regarding  the  fleas  as 
modified  and  specialised  Diptera — that  is  to  say,  as  descended 
from  fly-ancestors.  If  so,  they  may  have  once  possessed  a  crop 
such  as  is  found  in  the  fly,  but  which,  with  reduction  in  the  size 
of  the  body,  has  gradually  disappeared,  and  has  ceased  to  be 
developed.  Since,  as  has  been  pointed  out,  the  crop  is  formed  as 
a  diverticulum  of  the  oesophagus,  the  existence  of  such  an  organ 
in  the  ancestors  of  fleas  might  explain  the  persistence  of  a 
musculature  of  this  peculiar  type  in  the  oesophagus  of  the  flea. 
But  it  would  be  necessary  to  examine  the  oesophageal  muscula- 
ture of  other  insects  before  adopting  this  theory  as  an  explana- 
tion of  the  presence  of  stellate  muscle-cells  in  the  flea. 


DESCRIPTION   OF   PLATES. 

Plate  26. 

Abdominal  Nervous  Systems  of  the  Male  (left)  and 
Female  (right)  Flea,  magnified  90  Diameters. 

th.3,  metathoracic  ganglion  ;  abd.1,  abd.3,  abd.5,  and  abd.6,  first, 
third,  fifth,  and  sixth  abdominal  ganglia  ;  abd.7,  7th  abdominal 
ganglion,  present  in  the  male,  wanting  in  the  female ;  T.g., 
terminal  ganglion-complex.  Note  the  difference  in  the  size  and 
number  of  the  nerves  that  arise  from  T.g.  in  each  case. 

Plate  27. 
Salivary  Glands  of  the  Larval  and  Adult  Flea. 

A,  salivary  gland  of  the  larva,  magnified  60  linear  ;  d.,  duct, 
showing  at  its  distal  extremity  (to  the  right)  the  union  with  the 
corresponding  duct  from  the  other  side  of  the  body ;  a  small 
portion  of  the  duct  is  seen  magnified  400  linear;  r.,  reservoir; 
l.a.1  and  l.a.2,  the  two  anterior  lobes  of  the  gland  ;  l.p.,  the 
posterior  lobe. 

B  and  C,  the  salivary  glands  of  the  adult  flea,  at  B  magnified 
60  diameters,  for  comparison  with  A,  at  C  magnified  160;  d., 
duct ;   gl.,  the  two  pouch-like  glands. 


the  rat-flea,  ceratophyllus  fasciatus  bosc.  463 

Plate  28. 

General  View  of  the  Reproductive  Apparatus  of  the 
Male  Rat -flea,  seen  from  the  Right  Side. 

T,  T,  the  two  testes  ;  ep.1,  the  left  epididymis  in  its  natural 
coil ;  ep.2,  the  right  epididymis  forcibly  uncoiled  ;  v.d.1,  v.d.2,  the 
left  and  right  paired  vasa  deferentia ;  v.d.3,  the  common  vas 
deferens;  r.l.p.,  the  right  lateral  prostate  gland;  r.m.p.,  the 
right  median  prostate ;  d.ej.,  the  ductus  ejaculatorius ;  c.s.o., 
the  "  corkscrew-organ  "  ;  d.,  the  urethral  duct  running  spirally 
round  the  corkscrew-organ;    P,  the  penis.      x  75  linear. 

Plate  29. 

Chitinous  Skeleton  and  Principal  Muscles  of  the  Penis  and 
Corkscrew-organ  of  the  Male  Rat-flea,  from  the  Left 
Side. 

P,  penis;  e.p.,  external  plates  of  the  posterior  end  of  the  body; 
b.1,  chitinous  bar,  an  outgrowth  of  the  dorsal  integument ; 
b.2,  chitinous  bar  arising  from  the  ventral-posterior  end  of  the 
penis;  l.r.m.,  lateral  retractor  muscles  running  from  b.1  to  b.2 ; 
m.r.in.,  median  retractor  muscle  running  from  b.1  to  an  out- 
growth of  the  dorsal  side  of  the  penis ;  l.m.,  lateral  muscle 
running  from  the  side  of  the  penis  to  the  body -wall;  p.m.,  pro- 
tractor muscle,  running  from  b.1  to  the  penis;  c.s.o.,  corkscrew- 
organ  ;  ax.,  its  axial  skeleton  ;  d.,  the  urethral  duct ;  sp.z.,  sp  z., 
spermatozoa  in  the  duct,  indicating  its  course  where  the  cork- 
screw-organ passes  into  the  penis,      x  150  linear. 

Plate  30. 

Details  of  the  Male  Reproductive  System  more  highly 

magnified. 

A,  a  portion  of  one  of  the  coils  of  the  "corkscrew-organ,"  seen 
from  the  lower  surface;  d.,  the  urethral  duct,  running  at  the 
extreme  outer  edge  of  the  spiral;  ax.,  the  chitinised  axis  of  the 
spiral;  running  from  ax.  to  d.  are  the  superficial  radiating  muscles, 
clearly  seen  ;    below  the   radiating  muscles  two  structures  are 


464     E.    A.    MINCHIN    ON    THE    RAT-FLEA,    CERATOPHYLLUS  FASCIATUS. 

seen,  less  clearly ;  close  to  ax.  is  a  spiral  muscle,  sp.m.  ;  between 
sp.m.  and  d.  is  a  cushion  of  cells  with  nuclei,  apparently  glandular 
in  nature.      x  350. 

B,  a  portion  of  one  of  the  prostatic  tubules,  in  surface  view, 
showing  an  epithelium  composed  of  glandular  cells  with  very 
distinct  polygonal  outlines,      x  350. 

Plate  31. 
Accessory  Reproductive  Apparatus  of  the  Female  Rat-flea. 

U.S.,  receptaculum  seminis ;  m.r.s.,  muscles  connecting  the 
main  chamber  of  the  receptaculum  with  its  horn-shaped  pro- 
longation ;  gl.c,  cushion  of  gland-cells  surrounding  the  duct  at 
the  point  where  it  issues  from  the  receptaculum  ;  d.,  d.,  d.,  the 
long  coiled  duct  of  the  receptaculum,  seen  here  forcibly  uncoiled; 
gl.,  gland-cells,  thickly  crowded  on  the  proximal  part  of  the  duct; 
T.O.,  terminal  organ;  c.b.,  bar  of  thickened  chitin  on  the  wall  of 
the  termination  of  the  duct;  m.t.o.,  "bowstring"  muscle  of 
the  terminal  organ.  The  apparatus  is  seen  at  a  magnification 
of  200  linear ;  at  A  and  B  are  seen  portions  of  the  duct  magnified 
400  linear. 

Plate  32. 

Stellate  Muscle -cells  of  the  Oesophagus  of  the  Flea 
and  the  Crop  of  the  House-fly. 

A,  oesophagus  of  the  flea,  magnified  --0/--  linear,  showing  the 
muscular  network;  B,  a  detail  of  A,  magnified  1,000  ;  C,  a  detail 
from  another  specimen,  magnified  1,000,  showing  how  the  striated 
muscle-fibres  are  continued  through  the  cytoplasm  of  the  muscle- 
cells. 

D  and  E,  muscular  network  from  two  different  regions  of  the 
crop  of  the  house-fly ;  both  from  the  same  specimen,  and 
magnified  to  the  same  degree  as  A. 

Lister  Institute, 

January  'Z5th,  1915. 


Journ.  Qvekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  70,  April  1915. 


Journ.  Q.M.C. 


Ser.  2,  Vol.  XIL,  PL  29. 


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Anatomy  of  the  Rat-flea. 


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Ser.  2,  Vol.  XII,  PI.  31. 


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465 


THE   PRESIDENT'S   ADDRESS. 

THE    BIOLOGICAL  CONCEPTION   OF   INDIVIDUALITY. 

By  Prof.  Arthur  Dendy,  D.Sc,   F.R.S. 

{Delivered  February  23rd,  1915.) 

I  need  hardly  remind  you  that  the  organic  world,  as  we  know  it 
to-day,  is  divided  by  systematic  biologists,  largely  for  their  own 
convenience  and  in  accordance  with  their  own  particular  ideas, 
into  some  millions  of  different  kinds  or  species  of  plants  and 
animals,  and  that  each  of  these  so-called  species  consists,  usually 
at  any  rate,  of  millions  of  units  which  we  call  individuals. 

In  making  this  statement  we  most  of  us  probably  think 
that,  whatever  may  be  our  doubts  as  regards  species,  we  know 
very  well  what  we  mean  by  the  term  "individual";  we  can 
recognise  and  define  an  individual  man  or  dog,  or  an  in- 
dividual oak  tree  or  cabbage,  at  any  rate  to  our  own 
satisfaction.  If,  however,  we  carry  our  investigations  a  little 
below  the  surface  of  things  wre  soon  meet  with  cases  that  are 
not  a  little  puzzling,  and  my  purpose  this  evening  is  to  inquire, 
albeit  very  briefly,  whether  it  is  really  possible  to  frame  a 
definition  of  individuality  from  the  biological  standpoint  that 
will  be  of  general  applicability  throughout  the  animal  and 
vegetable  kingdoms ;  whether  we  are  really  much  better  off  in 
this  respect  in  dealing  with  individuals  than  we  are  in  dealing 
with  species. 

There  appear  to  me  to  be  two  main  paths  by  which  we  can 
approach  our  problem,  the  morphological  and  the  physiological. 
On  the  one  hand  we  can  inquire  what  constitutes  a  perfect 
individual  from  the  point  of  view  of  structure,  and,  on  the  other, 
what  constitutes  such  an  individual  from  the  point  of  view  of 
function.  In  the  case  of  the  higher  animals  we  might  approach 
the  question  in  a  third  way  and  inquire  what  constitutes  an 
individual  from  the  psychological  standpoint.  We  shall  find,  as 
we  pursue  our  investigations,  that  each  path  is  beset  with 
difficulties,  and  that  each  leads  to  some  very  curious  situations. 
We  shall   also  discover  that  the    three  paths  are  not  entirely 


466  the  president's  address. 

distinct,  but  frequently  run  together,  and  that  the  best  going  is 
sometimes  to  be  found  along  one  and  sometimes  along  another. 

Starting  along  the  morphological  road  Ave  shall  very  soon  find 
that  there  are  many  grades  or  orders  of  individuality,  and  that 
what  constitutes  a  perfect  individual  in  one  case  may  by  no 
means  do  so  in  another. 

Amongst  the  lower  forms  of  life  the  individual  frequently 
consists,  as  you  know,  of  a  single  cell,  a  single  nucleated  mass 
of  protoplasm  capable  of  performing  by  itself  all  those  actions  or 
functions  which  are  necessary  for  the  maintenance  of  life.  The 
cell  is,  of  course,  frequently  looked  upon  as  the  lowest  structural 
unit,  and  the  unicellular  plants  and  animals  as  individuals  of  the 
first  order.  It  may  fairly  be  questioned  whether  this  view  is 
strictly  correct,  for  the  nucleated  cell  has  already  progressed  a 
long  way  along  the  path  of  evolution,  and  it  is  quite  conceivable 
that  it  may  have  originated  as  a  colony  of  individuals  of  a  still 
lower  order — micellae,  plastidules,  biophors,  or  whatever  else  we 
like  to  call  them  ;  while  it  is  certain  that  some  existing  organisms, 
such  as  the  Bacteria,  have  not  yet  attained  the  level  of  perfect 
cells. 

We  know,  however,  that  all  the  higher  organisms  actually 
start  life  as  single  nucleated  cells,  formed  usually  by  the  union  of 
two  gametes  or  germ  cells,  and  that  these  germ  cells  themselves 
originate  as  complete  nucleated  cells  by  the  process  of  cell-division, 
and  not,  so  far  as  we  can  tell,  by  the  multiplication  and  addition 
of  units  of  a  lower  order.  This  fundamental  fact  seems  to  justify 
us  in  looking  upon  the  cell  as  the  lowest  morphological  unit,  and 
we  may  accordingly  accept  it  as  the  starting-point  for  our  inquiry. 

A  unicellular  organism,  after  attaining  a  certain  size,  and 
under  favourable  circumstances,  may  divide  into  two  parts  which 
completely  separate  from  one  another  and  form  two  new  and 
independent  individuals.  In  this  simple  process  of  reproduction 
the  parent  cell  ceases  to  exist  as  an  individual,  but  we  cannot  say 
that  it  perishes,  for  its  substance  is  merely  divided  between  the 
two  daughter  cells  and  there  is  nothing  left  over  to  die. 

In  the  multicellular  animals  and  plants  we  meet  with  a  very 
different  state  of  things.  Here  the  individual  is  composed,  not 
of  a  single  cell,  but  of  a  number  of  such  cells,  often  amounting  to 
very  many  millions,  all  united  together  in  one  body.  Moreover, 
these  cells  are   not  all  alike,    but   very    variously  differentiated 


THE    PRESIDENTS    ADDRESS.  467 

amongst  themselves  for  the  fulfilment  of  different  functions,  and 
all  co-operate  in  a  common  life  which  is  fuller  and  more  varied 
in  accordance  with  the  greater  complexity  of  structure.  This 
differentiation  and  division  of  labour  amongst  the  constituent 
cells  of  the  multicellular  body  has  undoubtedly  been  one  of  the 
chief  means  by  which  progressive  evolution  has  been  rendered 
possible.  From  the  point  of  view  of  the  individual,  however,  it 
has  its  drawbacks.  Each  cell  is  no  longer  self-sufficing,  it  can 
no  longer  perform,  by  itself  all  the  functions  necessary  for  con- 
tinued existence.  A  muscle  cell,  for  example,  is  dependent  upon 
the  blood  for  its  supply  of  food  and  oxygen,  upon  the  nervous 
system  for  its  means  of  communication  with  other  parts  of  the 
body,  and  upon  the  skin  for  its  protection.  It  can  do  its  own 
particular  job  remarkably  well,  but  only  by  sacrificing  the  power 
to  do  other  things  that  are  very  necessary  for  its  own  existence. 
It  has  ceased  to  live  as  an  independent  individual  and  has  become 
a  mere  constituent  part,  an  organ,  of  an  individual  of  a  higher 
order.  Moreover,  it  sooner  or  later  loses  the  power  of  reproducing 
itself  by  multiplication,  becomes  worn  out  and  dies.  So  it  is  with 
the  vast  majority  of  all  the  cells  of  which  the  multicellular  body 
is  composed.  They  become  worn  out  and  die,  and  the  body  as  a 
whole  perishes,  death  being  the  inevitable  price  paid  for  progress. 
Certain  cells  in  the  body,  however,  escape  the  general  debacle. 
These  are  the  germ  cells,  and  the  reason  for  their  exemp- 
tion seems  to  lie  in  the  fact  that  they  never  become  highly 
specialised,  never  exhaust  themselves  by  work,  and  never  lose  the 
power  of  multiplication.  They  survive  and  start  the  game  afresh. 
They  have  been  aptly  compared  to  so  many  unicellular  Protozoa 
enclosed  within  the  multicellular  body — in  it  but  not  of  it — and, 
like  the  Protozoa,  enjoying  at  least  a  potential  immortality. 

If  we  inquire  how  the  multicellular  condition  arose  from  the 
unicellular  in  the  course  of  evolution  we  find  an  answer  in  two 
directions.  In  the  first  place  the  existence  of  protozoon  colonies — 
especially  such  forms  as  Yolvox — shows  us  clearly  the  first  step  in 
the  transition,  and  in  the  second  place  we  see  the  actual  process 
repeated  with  more  or  less  accuracy  in  the  development  of  all  the 
higher  animals  from  the  unicellular  egg.  The  division  of  the  egg 
into  embryonic  cells  or  blastomeres  in  the  process  of  segmentation 
is  exactly  comparable  with  the  multiplication  of  an  amoeba  by  simple 
fission.    There  is  only  one  difference,  and  that  is  that  the  daughter 


468  the  president's  address. 

cells  all  remain  together  instead  of  separating.  Somehow  or  other 
they  have  learnt  the  value  of  co-operation.  At  the  close  of 
segmentation,  in  a  typical  animal  development  such  as  that  of  a 
sea  urchin,  or  even  of  so  highly  organised  a  form  as  Amphioxus, 
the  embryonic  cells  arrange  themselves  in  a  form  which  exactly 
reproduces  the  arrangement  seen  in  a  colony  of  Volvox,  giving  rise 
to  the  blastula,  a  hollow  spherical  embryo  with  a  wall  composed 
of  a  single  layer  of  cells. 

It  seems  fairly  certain,  from  such  considerations,  that  the  origin 
of  all  the  higher  animals  is  to  be  found  in  the  habit,  in  which 
so  many  Protozoa  indulge,  of  forming  colonies,  and  the  particular 
type  of  colony  which  has  led  to  the  best  results  appears  to  have 
been  that  adopted  by  Volvox  and  by  the  radiolarian  Sphaerozoum. 
The  branching  type  of  colony,  met  with  in  the  Vorticellidae  and 
many  other  groups,  appears  to  have  led  to  no  important  advance 
in  organisation,  and  we  shall  see  presently  that  this  holds  true 
also  in  the  case  of  higher  divisions  of  the  animal  kingdom. 

The  mere  habit  of  colony  formation  is  not,  however,  sufficient 
to  secure  progress  :  there  must  also  be  differentiation  and  division 
of  labour  amongst  the  constituent  cells,  so  that  the  entire 
organism  may  form  a  machine  of  greater  efficiency  in  the 
struggle  for  existence.  In  this  process  the  individual  cells 
become  mutually  dependent  upon  one  another — the  whole 
colony  undergoes  what  is  termed  integration,  and  comes  to  form 
a  single  individual  of  a  higher  order,  an  individual  which  cannot 
be  separated  into  its  constituent  parts  without  perishing. 

In  such  forms  as  Sphaerozoum,  Volvox,  and  the  blastula  stage 
in  the  development  of  higher  animals,  the  processes  of  differentia- 
tion, division  of  labour  and  integration  have  not  gone  very  far, 
and  such  forms  may  still  be  regarded  as  mere  colonies  of  single 
cells.  In  the  main  line  of  evolution  of  the  animal  kingdom  the 
next  step  appears  to  have  been  the  conversion  of  the  hollow 
spherical  colony  of  Protozoa  into  the  coelenterate  type,  a  process 
which  is  represented  in  every  typical  development  by  the  conver- 
sion of  the  blastula  into  the  gastrula. 

If  we  accept  the  familiar  principle  of  the  recapitulation  of 
ancestral  history  in  individual  development,  we  gain  a  very  clear 
idea  as  to  how  the  coelenterate  type  probably  arose.  The  hollow 
sphere  of  one  layer  of  cells  became  converted  into  a  sac  formed  of 
two  layers,  with  a   mouth  at  one   end  leading  into  a   primitive 


THE    PRESIDENT'S    ADDRESS.  469 

digestive  cavity.  This  process  actually  takes  place  in  a  variety 
of  ways  in  the  development  of  different  animals  at  the  present 
day,  and  we  need  not  stop  to  inquire  which  of  these  ways 
represents  most  closely  the  course  originally  followed  in  ancestral 
history. 

We  have  now  arrived  at  a  very  definite  type  of  multicellular 
structure — the  gastrula  of  embryologists — with  a  well-marked 
differentiation  of  the  constituent  cells  into  two  very  distinct 
groups  with  widely  different  functions — an  outer  protective  layer 
and  an  inner  layer  concerned  in  nutrition,  known  in  embryonic 
forms  as  epiblast  and  hypoblast,  in  adults  as  ectoderm  and 
endoderm  respectively. 

An  organism  possessing  this  type  of  structure  has  passed 
definitely  beyond  the  stage  of  a  mere  colony  of  Protozoa,  and 
constitutes  what  we  may  term  an  individual  of  the  second  order. 
The  best  and  most  familiar  example  of  such  an  individual  is  the 
freshwater  polype  Hydra,  which  differs  from  an  embryonic 
gastrula  in  little  more  than  the  budding  out  of  tentacles  around 
the  mouth  and  a  certain  amount  of  histological  differentiation 
amongst  the  constituent  cells  of  both  ectoderm  and  endoderm. 

The  organism  has  now  gained  a  fresh  starting-point  for  further 
evolution  ;  there  is  a  new  unit  of  a  higher  order  with  which 
to  build,  and  it  is  extremely  interesting  to  see  how  the  next 
really  great  advance  begins,  just  as  it  did  amongst  the  Protozoa, 
with  colony  formation. 

Almost  the  only  type  of  colony  met  with  amongst  the 
Coelenterata,  however,  is  the  branching  type,  but  the  mode  of 
branching  is  extremely  various.  No  great  advance  has  been 
attained  in  this  way,  though  some  of  the  colonies  produced  are  of 
much  interest  in  discussing  the  problem  of  individuality.  This 
is  especially  true  of  the  Siphonophora,  those  freely  floating  colonies 
of  Hydrozoa  which  form  such  an  important  constituent  of  the 
oceanic  plankton.  In  many  of  these  we  find  differentiation 
and  division  of  labour  amongst  the  constituent  individuals 
carried  to  such  a  high  degree,  and  accompanied  by  so  complete 
an  integration,  that  one  is  tempted  to  regard  them  as  something 
more  than  mere  colonies,  for  in  such  integrated  colonies  the  con- 
stituent individuals  tend  to  become  converted  into  mere  organs 
subserving  the  welfare  of  the  whole  and  quite  incapable  of 
independent  existence. 


470  the  president's  address. 

Take,  for  example,  such  a  form  as  Nectalia  or  Physophora. 
Here  we  have  a  large  number  of  individuals  or  zooids  attached 
to  a  common  stem.  At  the  upper  end  a  single  modified  in- 
dividual forms  a  float.  Along  the  length  of  the  stalk  two  rows 
of  differently  modified  individuals  form  swimming  bells,  which 
have  concentrated  their  energies  entirely  upon  the  function  of 
locomotion,  and  have  completely  lost  the  power  of  feeding  them- 
selves and  of  reproducing  their  kind.  At  the  bottom  of  the 
stalk  an  expanded  disc  bears  a  number  of  other  zooids.  Some 
of  these  have  mouths  and  stomachs,  and  fishing  tentacles 
provided  with  thread  cells,  and  their  duty  is  to  provide  and 
digest  food,  not  only  for  themselves  but  for  the  entire  colony. 
Others,  again,  form  protective  shields  or  bracts,  and  yet  others 
bear  the  germ  cells  upon  which  the  organism  depends  for 
reproduction. 

This  is,  clearly,  a  very  highly  organised  type  of  colony. 
Whether,  indeed,  we  should  still  call  it  a  colony  or  regard  it  as 
an  individual  of  the  third  order  is  a  debatable  question,  and 
one  which  is  of  no  vital  importance,  for  we  must  remember  that 
it  is  impossible  to  draw  hard  and  fast  lines  across  the  path  of 
evolution  and  say  that  all  on  one  side  of  a  given  line  is  one  thing 
and  all  on  the  other  side  something  else. 

At  any  rate,  such  colonies  seem  to  have  reached  the  limit  of 
their  progress,  and  have  not  afforded  any  fresh  starting-point 
from  which  a  new  line  of  evolution  has  originated. 

There  are,  however,  certain  other  Hydrozoa  which  exhibit  a 
type  of  colony  formation  that  seems  to  foreshadow  higher  possi- 
bilities. I  refer  to  the  common  jelly-fish  known  as  Scyphomedusae.' 
The  hydroid  phase  of  these  organisms  forms  temporary  colonies 
by  a  process  totally  different  from  branching.  The  entire 
hydroid  divides  transversely  into  a  heap  of  little  jelly-fish  or 
ephyrae,  resembling  a  pile  of  saucers.  These  remain  together 
for  a  while  and  form  a  kind  of  colony  known  as  a  strobila,  but 
presently  they  all  separate  and  swim  away. 

Amongst  the  coelenterates  this  process  of  strobilation  is  never 
accompanied  by  any  considerable  differentiation  and  division  of 
labour  amongst  the  constituent  individuals  of  the  colony,  and 
still  less  by  integration,  so  that  it  leads  to  no  higher  type  of 
organisation.  When  we  come  to  the  worms,  however,  which 
have  undoubtedly  arisen  from  coelenterate  ancestors,  we  find  in 


THE    PRESIDENT'S    ADDRESS.  471 

inany  cases  that  the  process  of  strobilation  assumes  much  greater 
importance,  and  finally  leads  to  a  new  type  of  structure  char- 
acterised by  what  zoologists  term  metameric  segmentation,  or 
serial  metamerism.  The  earthworm  is,  of  course,  a  typical 
example  of  such  a  metamerically  segmented  animal,  the  body 
consisting  of  a  number  of  distinct  segments  or  metameres  arranged 
in  linear  series  one  behind  the  other,  and  each  one,  to  a  certain 
extent,  repeating  the  structure  of  all  the  others,  each  with  its 
own  division  of  the  alimentary  canal,  its  own  division  of  the 
vascular  system,  its  own  division  of  the  excretory  system,  its  own 
division  of  the  nervous  system,  and  so  on,  but  all  united  together 
in  mutual  dependence  and  incapable  of  separate  existence. 

Differentiation  and  integration  have,  indeed,  gone  so  far  in 
the  case  of  the  earthworm  that  we  can  no  longer  regard  the 
animal  as  a  mere  strobila  or  linear  colony.  It  is  undoubtedly  a 
single  individual  of  the  third  order. 

In  some  other  groups  of  worms,  however,  the  process  of 
integration  has  hardly  commenced,  and  the  different  segments 
sooner  or  later  separate  from  one  another  as  distinct  individuals. 
We  see  a  good  example  of  this  in  the  Planarian  Microstoma 
lineare,  where  transverse  division,  frequently  repeated,  results  in 
the  formation  of  a  strobila  or  chain  of  perfect  individuals  that 
only  remain  temporarily  associated  with  one  another.  We  see 
something  of  the  same  sort  in  the  tape- worm,  which  consists  of 
a  chain  of  so-called  proglottides  attached  to  a  head  or  scolex,  and 
each  containing,  amongst  other  things,  a  complete  set  of  repro- 
ductive organs. 

Even  in  some  of  the  highly  organised  chaetopod  annelids,  the 
group  to  which  the  earthworm  belongs,  we  sometimes  find  new 
segments  being  added  to  the  chain  throughout  life,  by  a  kind  of 
linear  budding  or  transverse  division,  and  in  many  cases  groups 
of  segments  separate  off  from  time  to  time  as  independent 
individuals. 

The  earthworm,  however,  has  lost  the  power  of  reproducing 
independent  individuals  in  this  fashion.  The  process  of  integra- 
tion has  gone  too  far,  for  certain  essential  organs  have  become 
restricted  to  special  segments  and  separation  into  constituent 
units  is  no  longer  possible. 

The  same  phenomenon  of  metameric  segmentation  is  exhibited 
throughout    the  whole    of    the    great    group  Arthropoda,   which 


472  the  president's  address. 

indeed  are  in  all  probability  descended  from  annelid  ancestor 
The  common  crayfish,  for  example,  is  made  up  of  nineteen,  or, 
according  to  some  authorities,  twenty  segments,  each  having  its 
own  pair  of  limbs  or  appendages,  all  of  which  can  be  readily 
derived  from  one  and  the  same  common  type  of  structure.  In 
the  arthropods,  however,  we  find  the  process  of  integration 
carried  much  farther  than  it  is  in  the  annelids.  Any  ordinary 
insect,  as  you  know,  shows  a  well-marked  differentiation  into 
head,  thorax  and  abdomen,  each  of  which  is  composed  of  a 
number  of  segments  which  co-operate  in  the  fulfilment  of  some 
common  function,  or  rather  of  many  common  functions.  There 
is  not  only  differentiation  and  division  of  labour  between  individual 
segments,  but  the  segments  are  grouped  so  as  to  perform  their 
functions  more  advantageously. 

It  is  precisely  the  same  in  the  highest  phylum  of  the  animal 
kingdom,  the  Vertebrata.  These  are  all  metamerically  segmented 
animals,  derived  in  all  probability  from  some  metamerically 
segmented,  worm-like  ancestral  form.  The  process  of  integration 
has  gone  so  far,  however,  that  but  few  indications  are  left, 
externally  at  any  rate,  of  their  origin  ;  though  we  see  abundant 
traces  of  serial  metamerism  in  their  internal  organisation,  as  for 
example  in  the  segmented  vertebral  column  and  the  segmentally 
arranged  cranial  and  spinal  nerves.  In  the  early  stages  of  develop- 
ment the  metameric  segmentation  is  much  more  obvious  and 
cannot  possibly  be  overlooked. 

It  may  seem  absurd  enough  to  the  layman  to  say  that  the 
human  head  is  made  up  of  at  least  twelve  segments,  each  of 
which  corresponds  to  a  complete  individual  in  some  remote 
ancestral  linear  colony,  but  the  statement  is  in  all  probability 
strictly  true. 

In  the  main  line  of  evolution  of  the  animal  kingdom,  then, 
we  can  recognise  three  very  distinct  grades  or  orders  of  indi- 
viduality from  the  morphological  point  of  view.  First,  the  single 
cell,  as  in  the  Protozoa ;  second,  the  simple  multicellular  type,  as 
in  the  Coelenterata  and  the  majority  of  the  flatworms,  and 
third,  the  metamerically  segmented  type,  as  in  the  annelid 
worms,  the  arthropods  and  the  vertebrates  ;  and  each  succeeding 
higher  grade  has  been  derived  from  the  one  below  it  through  the 
process  of  colony  formation,  followed  by  differentiation,  division 
of  labour  and  integration. 


THE    PRESIDENT'S    ADDRESS.  473 

From  this  point  of  view  it  is  clearly  impossible  to  establish 
any  definite  criterion  of  individuality  of  general  applicability,  for 
it  is  impossible  to  say  exactly  when  a  colony  ceases  to  be  a  colony 
and  becomes  an  individual  of  a  higher  order.  Our  ideas  of 
individuality  change  completely  as  we  review  the  animal  kingdom 
from  the  Protozoa  upwards. 

It  might  be  supposed  that  some  light  would  be  thrown  upon 
our  problem  by  the  study  of  the  development  of  the  individual 
from  the  egg,  and  this  is  certainly  a  very  profitable  line  of  inquiry. 
Can  we  say  that  we  mean  by  an  individual  the  whole  undivided 
body  into  which  the  egg-cell  develops  1  We  certainly  can  in  many 
cases,  but  there  are  many  other  cases  in  which  we  just  as  certainly 
cannot. 

Let  us  return  for  a  moment  to  the  simple  hydroid  colony,  as 
we  see  it,  for  example,  in  Obelia  or  Sertularia.  Here  the  fertilised 
egg  develops  first  into  a  single  multicellular  individual,  but  that 
individual  does  not  stop  developing  when  it  has  attained  its  full 
growth ;  it  branches  out  and  produces  other  individuals  by  a  pro- 
cess of  budding,  and  in  the  colony  thus  formed  it  is  impossible  to 
say  where  one  individual  ends  and  another  begins,  though  it  may 
be  quite  possible  to  tell  how  many  individuals  there  are  altogether 
by  simply  counting  heads.  It  is  not,  as  a  rule,  until  many  non- 
sexual individuals  have  been  produced  that  some  particular  bud 
develops  into  a  new  sexual  individual  which  once  more  produces 
eggs  or  sperm.  Moreover,  in  this  alternation  of  sexual  and  non- 
sexual generations  the  two  generations  generally  differ  widely 
from  one  another  in  structure,  the  sexual  jelly-fish  being  strongly 
contrasted  with  the  non-sexual  hydroid  polype. 

A  similar  phenomenon  of  alternation  or  metagenesis  occurs,  of 
course,  in  many  other  animals  and  in  all  the  higher  plants, 
usually  accompanied  by  great  multiplication  of  the  non-sexual 
generation  by  some  process  of  budding.  An  ordinary  tree  is  the 
non-sexual  generation,  and  we  can  get  as  many  individuals  out 
of  it  as  we  like  by  taking  buds  or  cuttings,  though  we  are 
accustomed  to  look  upon  the  whole  tree  as  a  single  individual. 

A  difficulty  of  quite  a  different  kind  is  presented  by  the  lichens, 
which  are  well  known  to  be  composite  organisms,  made  up  of 
combined  algal  and  fungal  constituents,  and  by  the  myxomycetes, 
where  the  plasmodium  is  formed  by  the  union  of  a  number  of 
separate   amoebulae.     Here    we   get   a   number   of   individuals, 

Journ.  Q.  M.  C,  Series  II.— No.  76.  33 


474  the  president's  address. 

originally  quite  separate,  and  even  of  different  parentage,  com- 
bining to  form  an  individual  of  a  higher  order  of  quite  a  different 
nature  from  any  produced  by  ordinary  colony  formation. 

Such  mixed  individuals  are  rare  in  a  state  of  nature,  but 
various  experiments  show  that  they  are  quite  easily  produced 
artificially  in  certain  cases.  We  can  make  mixed  or  composite 
individuals  by  the  process  of  grafting  both  in  plants  and  animals 
It  is  by  no  means  difficult  to  graft  together  parts  of  two  hydras. 
We  can  even  join  the  hind  part  of  one  tadpole  to  the  front  part 
of  another,  and  the  product  may  develop  into  a  complete  frog, 
derived  possibly  from  individuals  of  two  distinct  species. 

Modern  surgery  has  enabled  us  to  perform  marvellous  grafting 
operations  even  upon  the  human  subject.  A  few  years  ago 
an  account  was  published  of  a  girl  whose  knee-joint  had  been 
removed  and  replaced  by  that  of  another  person,  with  perfect 
success.  Theoretically,  and  apart  from  the  difficulties  of  technique, 
there  seems  to  be  no  limit  to  the  possibilities  of  surgery  in  this 
direction.  It  would  almost  seem  as  if  the  whole  organism  were 
made  up  of  a  number  of  interchangeable  standard  parts,  like  a 
bicycle.  Suppose  it  were  possible  to  carry  on  the  process  until 
all  the  parts  of  the  body  had  one  by  one  been  replaced  by  others, 
what  would  be  the  result  from  the  point  of  view  of  individuality  ? 
Should  we  be  able  to  say  that  the  same  individual  still  existed 
after  all  the  operations  had  been  carried  through  ?  It  reminds 
us  of  the  Irishman's  knife,  that  at  various  times  had  had  all 
the  blades  replaced  and  a  new  handle,  but  was  still  to  him  the 
same  knife. 

Other  experiments  have  shown  that  it  is  possible  to  produce 
mixed  individuals  by  joining  together  embryonic  cells  or  blasto- 
meres  derived  from  different  eggs.  Garbowski  in  1904  succeeded 
in  uniting  blastomeres  derived  from  different  embryos  of  a  sea- 
urchin,  either  by  hydraulic  pressure  or  by  squeezing  them 
together  by  means  of  glass-headed  pins.  The  fragments  of  the 
divided  embryos  were  coloured  intravitally  with  various  stains 
that  did  not  injure  them,  so  that  they  could  be  readily  distin- 
guished from  one  another.  Even  when  the  blastomeres  were 
taken  from  embryos  in  different  stages  of  development,  the 
composite  embryos  formed  from  their  union  developed  into 
uniform  pluteus  larvae  by  means  of  various  regulation  processes. 

An   American  biologist,  H.  V.   Wilson,  has  shown  that  if  a 


THK    PRESIDENT'S    ADDRESS.  475 

hydroid  colony,  such  as  Eudendrium  or  Pennaria,  be  cut  up 
into  small  pieces  and  then  squeezed  through  fine  silk  gauze, 
it  is  reduced  to  a  kind  of  cream  or  pulp  in  which  the  constituent 
cells  are  more  or  less  completely  separated  from  one  another.  If 
kept  under  suitable  conditions,  however,  in  pure  sea-water,  the 
separate  cells  join  together  again  in  irregular  assemblages, 
to  which  Wilson  has  given  the  name  "  restitution  masses," 
and  such  a  restitution  mass  may  behave  like  an  embryo  and 
develop  into  a  new  hydroid  colony.  The  cells  arrange  themselves 
in  the  proper  layers,  ectoderm  and  endoderm ;  the  ectoderm 
secretes  a  new  horny  perisarc,  branches  grow  out,  and  finally 
new  hydroid  polyps  are  produced  at  the  ends  of  the  branches. 

It  is  impossible  in  such  a  case  to  formulate  any  definite 
relations  between  the  component  individuals  of  the  original 
colony  and  those  of  the  new  colony  developed  from  the  restitution 
mass.  The  whole  thing  was  simply  pulped,  and  the  separated 
cells  apparently  reduced  to  an  indifferent  condition  with  powers 
of  fresh  association  in  new  combinations,  while  many  of  the 
original  cells  seem  to  be  used  simply  as  food-material  for  the 
new  colony. 

This  experiment  is  to  some  extent  paralleled  by  what  takes 
place  normally  in  the  development  of  the  gemmules  of  the 
freshwater  sponge.  A  number  of  wandering  amoebocytes, 
charged  with  food-yolk,  migrate  to  one  spot  in  the  parent 
sponge,  and  there  become  enclosed  in  the  characteristic  capsule 
secreted  by  surrounding  cells.  On  germination  the  capsule  is 
ruptured,  and  an  amoeboid  mass  creeps  out ;  the  constituent 
cells  behave  like  the  blastomeres  of  an  ordinary  embryo,  multiply 
rapidly  and  become  differentiated  into  the  various  tissue  cells, 
which  arrange  themselves  in  the  manner  characteristic  of 
the  adult. 

Such  phenomena  certainly  suggest  the  existence  of  some  directive 
influence  which  enables  the  separate  parts  to  co-operate  in  the 
formation  of  a  whole  individual,  but  what  is  the  nature  of  this 
directive  influence  and  where  it  is  located  are  complete  mysteries. 
We  have  now  inquired,  so  far  as  time  permits,  into  the 
question  whether  or  not  it  is  possible  from  the  morphological 
point  of  view  to  give  any  definition  of  individuality  of  general 
applicability.  We  have  seen  that  in  the  course  of  evolution 
individuals  of  a  lower  order  have  given  rise  to  individuals  of  a 


476  the  president's  address. 

higher  order  through  the  process  of  colony  formation  and  integra- 
tion, and  that  it  is  quite  impossible  to  draw  hard  and  fast  lines 
between  the  successive  terms  of  the  series.  We  have  seen  also 
that  even  amongst  highly  organised  plants  and  animals  individua- 
lity does  not  depend  upon  the  preservation  of  the  same  identical 
parts  in  the  same  association.  Individuals  may  be  subdivided 
and  joined  together  in  a  variety  of  ways,  and  parts  of  different 
individuals  may  be  interchanged  without  impairing  their  vitality. 
In  short,  we  can  by  no  means  frame  a  general  morphological 
definition  of  individuality. 

Are  we  any  better  off*  when  we  ask  what  constitutes  an 
individual  from  the  physiological  standpoint  ?  A  criterion  of 
individuality  is  indeed  often  sought  in  the  power  to  perform  all 
the  essential  vital  functions,  or,  in  other  words,  to  live  a  com- 
pletely independent  life.  A  unicellular  organism  does  everything 
for  itself.  It  feeds,  respires,  gets  rid  of  its  waste  products  and  so 
forth,  all  in  a  very  simple  but  at  the  same  time  efficient  manner. 
A  single  cell  of  one  of  the  higher  plants  or  animals,  on  the  other 
hand,  though  it  may  live  independently  for  some  time  in  a 
suitable  medium,  cannot  do  so  indefinitely.  It  has  sacrificed  the 
power  of  doing  everything  for  itself  to  the  power  of  doing  some 
one  particular  thing  more  efficiently,  and  depends  for  its  con- 
tinued existence  upon  the  co-operation  of  innumerable  other 
cells.  Similarly,  a  single  highly  specialised  individual  of  a 
siphonophoran  colony,  such  as  a  swimming  bell  of  Physophora, 
is  quite  incapable  of  independent  existence ;  from  the  physio- 
logical point  of  view  the  colony  as  a  whole  constitutes  the 
individual,  though  the  morphologist  has  little  difficulty  in 
recognising  the  component  members. 

This  leads  us  to  the  consideration  of  certain  other  cases  of 
great  interest.  Many  of  the  higher  animals,  though  they  do 
not  form  colonies  in  the  morphological  sense,  have  the  habit  of 
living  together  in  social  communities  which  we  might  regard  as 
colonies  of  completely  separated  individuals.  The  honey  bee  is 
a  familiar  example.  In  a  hive  of  bees  we  find  individuals  of 
three  kinds,  easily  distinguishable  from  one  another  both  by 
habits  and  by  structural  peculiarities.  The  queen  is  a  perfect 
female,  and  is  alone  capable  of  laying  eggs.  The  ordinary 
workers  are  imperfect  females  which  have  sacrificed  the  power 
of  reproduction  and  concentrate  their  energies  upon  the  collection 


THE    PRESIDENT'S    ADDRESS.  477 

of  food  and  other  important  services  necessary  for  the  welfare  of 
the  community  as  a  whole.  The  drones  are  males  j  they  do 
no  ordinary  work,  their  sole  function  being  to  fertilise  the  queen. 
None  of  these  different  kinds  of  individuals  could  live  a  really 
independent  life ;  they  are  all  mutually  dependent  upon  one 
another.  The  morphologist,  however,  would  not  hesitate  to 
regard  them  all  as  separate  individuals,  and  I  suppose  the 
physiologist  would  probably  agree  with  him.  But,  if  we  are  to 
be  strictly  logical,  from  the  physiological  point  of  view  the 
complete  individual  can  be  nothing  less  than  the  entire  community. 
From  this  point  of  view,  indeed,  such  communities  might  be 
looked  upon  as  individuals  of  yet  a  fourth  order,  but  in  which, 
from  the  nature  of  the  case,  morphological  integration  is  no 
longer  possible.  It  is  much  the  same  with  human  societies,  in 
which  the  component  individuals  become  more  and  more  dependent 
upon  one  another  as  civilisation  progresses. 

But,  you  may  say,  there  can  at  least  be  no  doubt  about 
the  individuality  of  my  own  self.  I  have  my  own  personality, 
complete  and  indivisible.  Here  we  approach  the  psychological 
aspect  of  our  problem,  into  which  I  do  not  propose  to  enter. 
I  have  no  doubt,  however,  that  the  psychologist  would  tell 
us  that  perhaps,  after  all,  we  may  be  mistaken  in  supposing 
that  we  can  attain  a  sharply  defined  conception  of  individuality 
even  in  his  province.  Remarkable  but,  fortunately,  abnormal 
cases  are  well  known,  in  which  two  or  more  personalities 
alternate  with  one  another  in  the  life  of  what,  from  both  the 
morphological  and  physiological  points  of  view,  we  unhesi- 
tatingly call  a  single  individual. 

It  appears,  then,  to  be  a  hopeless  task  to  seek  for  any 
biological  criterion  of  individuality  that  can  be  applied  to  more 
than  a  very  limited  number  of  cases.  We  have  constantly 
to  modify  our  ideas  on  the  subject  as  we  pass  from  one  group 
of  organisms  to  another,  and  everything  depends  upon  the  point 
of  view.  It  is  certain,  however,  that,  whatever  else  an  in- 
dividual may  be,  it  is  something  which  works  as  a  whole 
for  its  own  self-preservation  and  self-expression,  and  is  more 
or  less  antagonistic  towards  other  individuals  with  which  it 
comes  into  relation  in  the  struggle  for  existence. 

Other  facts  that  emerge  quite  clearly  from  our  inquiry 
are   that   co-operation,    differentiation,    division   of   labour   and 


478  the  president's  address. 

integration  amongst  individuals  of  successively  higher  orders 
constitute  some  of  the  most  important  factors  by  means  of  which 
organic  evolution  is  carried  on,  and  that  at  each  successive  stage 
of  progressive  integration  a  new  individuality  is  acquired,  the 
organism  entering  into  possession  of  new  attributes  that  are 
something  very  much  more  than  the  mere  sum  of  the  attributes 
possessed  by  its  constituent  units. 

Individuality,  though  a  very  real  phenomenon,  is  a  very 
elusive  one,  and  one  which  perhaps  lies  outside  the  legitimate 
domain  of  the  biologist.  We  can  do  little  more  than  collect 
the  remarkable  facts  that  confront  us  so  frequently  in  the  course 
of  our  investigations,  and  hand  them  over  to  the  philosophers 
to  deal  with  as  best  they  can.  How  far  the  philosophers  will 
agree  that  progressive  evolution  consists  to  a  very  large  extent 
in  the  gradual  merging  of  individualities  of  a_  lower  order  in 
others  of  a  higher  order  I  do  not  know,  but  to  myself  as 
a  biologist  this  generalisation  appears  to  hold  a  large  measure 
of  truth. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  76,  April  1915. 


479 


BRITISH    HYDRACARINA:    THE   GENUS   LEBERTIA. 

By  W.  Williamson,  F.R.S.E.,  and  Charles  D.  Soar, 

F.L.S.,  F.R.M.S. 

{Bead  March  23rd,  1915.) 

Plates  33-34. 

In  his  posthumous  memoir  published  in  1879,  under  the  title  of 
"  Description  de  quelques  especes  nouvelles  d'Hydrachnides   du 
Lac   Leman,"  *  Lebert  described    a    hydracarid  which  he  con- 
sidered to  be  new  on  account  of  the  form  of  its  genital  area. 
He   gave  it   the    name  of    Pachygaster    tau-insignitus,    and   he 
explained   the   specific  name   by   referring   to   the   resemblance 
which  the  light  dorsal  marking  bore  to  the  Greek  letter  tau  (t). 
As   to  why  he  selected  Pachygaster  as  a  generic  name,  he  has 
left  us  in  the  dark.     The  selection,  however,   was  not  a  happy 
one,    as   Meigen   used   it   in    1803    (Diptera),    Germar  in    1817 
(Coleoptera)  and   Gray  in  1840  (Echinodermata).f     In  the  year 
following  the  publication  of  Lebert's  memoir,  Neuman  changed 
the    generic   name  to   Lebertia.  %      One    can    without   difficulty 
comprehend  how,  from  the  lack  of  detail,  several  species  were 
identified  as  tau-insignitus ;  and  although  some  few  species  were 
described   by  Koenike   and  Piersig,  it  was  not  until  after   Sig 
Thor's   exhaustive   study  of  the  genus   that   its   comprehensive 
character    was    recognised.       The    result    was,    that    although 
tau-insignitus  had  been  naturally  designated  as  type,  the  working 
out  of   the  species  which  had  been  identified  as  tau-insignitus  led 
to  the  creation  of  other  species,  so  that,  curiously  enough,  tau- 
insignitus  was  worked  out  of   existence  altogether.      Sig  Thor 
apparently  recognised  the  illogical  position  which  had  arisen,  for 
we  find  that  later  on  he,  in  company  with  the  late  Prof.  Forel, 
examined  the  locality  at  Morges  where  Lebert  had  obtained  his 
specimens  at  a  depth  of  25  m.     They  were  successful  there  in 
obtaining   material  which  proved    on  examination  to   be   quite 
distinct  from   anything  previously  described.      As  other  repre- 
sentatives of   the  genus  were  not  met  with,  one  may  conclude 

*  Bull.  Soc.  Vaud.,  xvi.  327-377. 

■f  Nomen.  Zool.  Agassiz. 

%  Kgl.  Sv.  Vet.  Akad.  Handl.,  xvii.  (3)  68. 


480      W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

with  Thor  that  he  and  Lebert  had  obtained  the  same  species  in 
the  restricted  area.  But  in  re-establishing  the  species,  Sig  Thor 
overlooked  the  fact  that  it  had  been  previously  designated  as 
type,  and  consequently  we  find  that  the  original  genotype  and 
the  type  of  the  sub -genus  to  which  the  genotype  belongs  are  not 
the  same  species.  Further  we  find  that  the  sub-genus  containing 
the  genotype  bears  a  different  name  from  the  genus,  but  one  feels 
sure  that  the  rules  laid  down  for  guidance  in  such  cases  by  the 
International  Zoological  Congresses  have  been  overlooked  by  the 
indefatigable  Norwegian  acarologist  not  by  design,  but  purely  by 
accident.     To  this  we  shall  revert  later. 

A  more  troublesome  matter,  however,  is  the  consideration  of 
two  of  Koch's  species  as  members  of  the  genus  Lebertia,  viz. 
Hygrobates  iconicus  C.  L.  Koch,  and  H.  inaequalis  0.  L.  Koch, 
the  former  as  a  doubtful  species,  the  latter  as  valid.  These  are 
represented  in  Koch's  Deutschlands  Crustaceen,  Myriapoden  und 
Arachniden  in  Heft  11-22/23  and  Heft  11-20/21  respectively. 
As  Koch's  work  is  not  to  be  found  in  many  of  our  libraries,  it 
will  not  be  out  of  place  to  reproduce  here  Koch's  descriptions  of 
the  above  species ;  and  as  these  can  be  taken  as  typical  of  the 
descriptions  in  Koch's  great  work,  workers  who  have  not  hitherto 
had  access  to  it  will  comprehend  something  of  the  difficulty 
attending  the  identification  of  many  of  Koch's  species,  difficulties 
which,  moreover,  are  not  rendered  more  easy  of  solution  by  his 
figures  of  species. 

11.  22  foem.,  23  mas. 

Hygrobates  iconicus. 

H.  subglobosus,  Jlavus,  nigro-pictus,  pedibus  ciliis  nullis. 

Gross,  fast  kreisrund,  doch  ein  wenig  langer  als  breit,  gewolbt, 
glanzlos,  zwei  grosse  Griibchen  hinten  an  dem  Mittelfleck,  zwei 
auf  dem  Riieken  des  Hinterleibs,.  das  Bruststiick  vorn  in  zwei 
Zahne  verl'angert.  Die  Taster  massig  lang,  ohne  Auszeichnung. 
Die  Beine  diinn,  die  vordern  kurz,  kaum  so  lang  als  die 
Korperbreite,  die  hintern  langer,  alle  kurzborstig,  ohne 
Schwimmhaare. 

Gelb,  die  Flecken  braunschwarz  oder  schwarz :  die  Mittelfleck 
kurz,  fast  von  der  Gestalt  eines  Quadrats ;  die  Seitenflecken  bis 
zum  Auge  ziehend,   breit,  nicht  lang.     Die  Riickenstreifen  mit 


THE    GENUS    LEBERTIA.  481 

dem  Winkelflecken  zusammenhangend,  zusammen  genommen 
zwei  stark  zackige  Bander  vorstellend  :  der  nach  diesen  Bandern 
seitwarts  gezackte  Gabelstreif  heller  gelb.  Unten  die  Grundfarbe 
wie  oben,  die  Zackenstreifen  von  oben  durchscheinend,  aber  weiter 
von  einander  und  in  die  Brust  ziehend.  Taster  und  Beine  ocher 
gelblich,  meistens  etwas  aufs  erdgriine  ziehend. 

Das  M'annchen  ist  kaum  halb  so  gross  als  das  Weibchen, 
meistens  heller  gef'arbt,  und  der  zackige  Gabelstreif  breiter,  die 
Zackenstreifen  aber  schm'aler. 

Variirt  ubrigens  mannichfaltig,  so  dass  Vorder-  und  Hinter- 
leibsflecken  zusammen  fliessen,  die  ganze  Riickenflache  schwarz 
farben  und  nur  eine  sehr  schmale  Spur  des  Gabelstreifs  iibrig 
lassen.  Die  Farbe  der  Beine  verdunkelt  sich  bis  zum  schwarzlich 
grunen. 

In  dem  Wiesengraben  bei  Zweibriicken  im  Monat  Juli,  nicht 
selten. 

11.  20  mas.,  21  foem. 

Hygrobates  inaequalis. 

H.    aurantiacus,   furca   angusta    albida,    maculis    omnibus    con- 
junctis,  olivaceis,  utrinque  lobatis,  pedibus  breviusculis  glaucis. 

Kaum  mittelgross,  kurz  eiformig,  der  Riicken  gewblbt,  glanzend, 
mit  sechs  Griibchen,  zwei  beiderseits  hinten  am  Mittelfleck,  die 
zwei  hintern  davon  von  einander  entfernter,  die  zwei  des  Hinter- 
leibs  auf  der  Mitte  des  Riickens  einander  mehr  gen'ahert ;  das 
Bruststuek  flach,  stark  vorstehend,  beiderseits  der  Taster  in 
eine  scharfe  Spitze  verlangert.  Die  Taster  ziemlich  lang,  diinn, 
die  Beine  aber  st'ammig,  ziemlich  lang,  mit  beweglichen  biischel- 
f  brmigen  Schwimmharchen  an  den  vier  Hinterbeinen. 

Der  Korper  blass  orangegelb,  zuweilen  auch  ziemlich  sattfarbig, 
Seiten-  und  Riickenflecken  zusammengeflossen,  ;olivengriin,  mit 
hellern  Punkten  und  Fleckchen,  meistens  aber  zwei  grovsse  seit- 
warts lappige  Ruckenfelder  vorstellend ;  der  Gabelstreif  schmal, 
kurzarmig,  mit  zwei  Eckchen  auf  dem  Riicken  ;  der  Mittelfleck 
zuweilen  aufs  rostrbthliche  ziehend,  entweder  nur  hinten  durch 
eine  feine  Linie  mit  den  Seiten flecken  verbunden  oder  frei.  Die 
Unterseite  des  Korpers  gelblich,  griin  angelaufen,  mit  einem 
olivengriinen  Schatten  an  den  Hiiften  und  einem  Schattenstreif 
auf  der  Mitte.     Bruststiick,  Taster  und  Beine  bl'aulich  griin. 


482     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

Das  Mannchen  ist  nicht  halb  so  gross  als  das  Weibchen,  hat 
mehr  zusammengefiossene  Riickenflecken  und  stets  einen  rost- 
braunen  Mittelfleck  des  Vorderleibs  ;  die  Unterseite  ist  dunkler 
griin  iiberlaufen  und  der  durchscheinende  Mittelfleck  auf  der 
Brust  rbthlich  sichtbar.  Bruststiick,  Taster  und  Beine  sind 
heller  und  weniger  stammig.  Am  Hinterrande  beiderseits  ein 
Eindruck. 

Variirt  ins  blassfarbige ;  bei  sehr  hellfarbigen  Exemplaren 
fehlen  die  hintern  Flecken  und  alsdann  erscheint  das  hintere 
Drittel  des  Kbrpers  durchsichtig  weisslich. 

Im  Schwarzbach  bei  Zweibriicken  in  Rheinbayern  sehr 
gemein. 

It  will  be  seen  at  once  that  Koch  makes  much  of  colour  and 
of  the  shape  of  the  colour  patches,  and  as  these,  as  Koch  himself 
admits,  are  variable,  dependence  placed  on  them  for  identification 
is   apt  to  lead  to   confusion.       Nor  do  the   scrappy  structural 
details  bring  us  any  nearer  a  decision  as  to  what  precisely  is. 
intended.      Some  colour   is  lent  to    Sig  Thor's  contention  that 
these  are  Lebertiad   species  in  respect    that   iconicus   is   rough 
skinned  (glanzlos),  has  no  swimming  hairs  and  has  the  epimera 
(Bruststiick)  produced  into  two  sharp  teeth,  one  on  each  side  of 
the  palpi.     Inaequalis  is  smooth  skinned,   has  swimming  hairs 
and  has  the  epimera  as  in   iconicus.     The  first  may  belong  to 
sub-genus  Lebertia  ( =  Neolebertia  Sig  Thor)  or  to  Pseudolebertia. 
The  second  may  be,  as  Thor  has  placed  it,  a  Pilolebertia  species. 
If  we  turn  to  Koch's  figures,  we  observe  that  iconicus  (fig.  23)  alone 
represents  the  palpi  with  the  long  hairs  so  characteristic  of  the 
genus  Lebertia,  though  not  in  any  detail,  merely  indicating  the 
existence  of  such.     The  ground  is  so  uncertain  that  Thor  admits 
with  respect  to  iconicus  that  exact  identification  is  out  of  the 
question  and  that  the  most  that  can  be  done  is  to  record  it  as 
Lebertia  iconica  (C.  L.  Koch)  sp.  dub. 

With  regard  to  inaequalis,  Thor  admits  the  difficulty  in 
deciding  that  figs.  20  and  21  represent  the  same  species.  If 
we  consider  what  appears  to  represent  the  natural  size  of  each, 
we  are  led  rather  to  the  view  that  instead  of  a  male,  fig.  20 
represents  a  young  nymph,  which  would  probably  account  for 
the  absence  of  swimming  hairs  on  the  second  pair  of  legs.  These 
are  shown  distinctly  on  the  second  pair  of  legs  in  fig.  21,  though 


THE    GENUS    LEBBRTIA.  483 

the  text  only  refers  to  swimming  hairs  on  the  two  posterior  pairs. 
Based  on  the  capture  of  specimens  of  Lebertia  at  Zweibriicken 
(Koch's  locality),  which  Thor  believes  to  be  identical  with  Koch's 
species,  Thor  has  redescribed  the  species  as  Lebertia  inaequalis 
(Koch,  1837)  Sig  Thor,  1900.  This  has  been  acknowledged  as 
valid  by  Continental  writers,  for  records  have  appeared  since 
then  from  Switzerland,  Italy  and  even  from  Turkestan. 

As  to  the  grouping  of  the  component  genera  of  the  Hydra- 
carina,  various  suggestions  have  been  made.  These  have  been 
discussed  by  Wolcott  in  his  Review  of  the  Water  Mites*  In 
his  classification  he  groups  Nilotonia,  Lebertia,  Oxus,  Frontipoda, 
and  Gnaphiscus  as  sub-family  Lebertiinae.  In  Koenike's  later 
classification  f  the  sub-family  Lebertiinae  covers  the  last  four 
of  these  genera,  Nilotonia  being  transferred  to  another  sub- 
family. Thor's  Prodromus,%  published  in  1900,  included  several 
other  genera  in  addition  to  those  noted  by  Koenike,  and  these 
Thor  designated  as  Family  Lebertiidae.  The  Prodromus  does 
not  discuss  the  matter,  and  owing  to  this  want  it  does  not  appear 
to  have  obtained  favour  among  acarologists.  Probably  Koenike's 
classification  may  be  found  to  represent  more  closely  than 
hitherto  the  natural  grouping  of  the  genera,  but  until  we  know 
more  of  the  larval  forms  a  definite  expression  of  opinion  must  be 
postponed. 

Sig  Thor  makes  some  interesting  reflections  on  the  phylogeny 
of  Lebertia.  In  the  absence  of  a  sufficient  knowledge  of  the 
larvae,  he  has  had  recourse  to  the  nymphal  forms  in  conjunction 
with  the  imagines  for  clues  as  to  what  course  the  line  of  descent 
might  take.  He  conceives  a  hypothetical  form  Urolebertia,  from 
which  spring  two  other  hypothetical  forms,  Protoxus  and  Proto- 
lebertia — the  former  leading  up  to  Gnaphiscus,  Oxus  and  Fronti- 
poda,  and  the  latter  to  the  sub-genera  of  Lebertia.  Of  these, 
Pseudolebertia,  Hexalebertia  and  Mixolebertia  are  the  three 
branches  which  have  a  common  hypothetical  ancestor  in 
Protolehertia.  Descent  is  continued  into  Pilolebertia  and  Lebertia 
(  =  Neolebertia),  the  former  appearing  to  have  qualities  which 
may  be  designated  as  of  a  dominant  and  the  latter  of  a  recessive 
type. 

*  Trans.  Amer.  Micro.  Soc.,  xxvi.  205. 

f  Abh.  Nat.  ver.  Bremen,  xx.  144. 

%  Nyt.  Mag.  / 'or  Nature.,  xxxviii.  (3),  263-266. 


484     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

Sig  Thor's  exhaustive  study  of  Lebertia  has  shown  that  the 
genus  can  be  resolved  into  two  groups  covering  five  sub-genera. 
In  the  first  group  the  skin  is  dotted  over  with  fine  pores,  and 
may  be  described  as  smooth,  as  it  is  without  the  papillae  or 
ridges  found  in  the  second  group.  Swimming  hairs  are  always 
present,  though  in  rare  cases  these  may  be  rudimentary.  The 
spines  on  the  extensor  surface  of  the  first  segment  of  the  fourth 
pair  of  legs  also  appear  to  lend  themselves  towards  the  dis- 
crimination of  the  groups,  as  the  second  group  may  have  from 
five  to  ten,  while  the  first  group  only  has  three  or  four,  though 
L.  obscura  forms  a  slight  exception,  as  it  has  five  or  six. 

Two  sub-genera,  Lebertia  (Sig  Thor's  Neolebertia)  and  Pilo- 
lebertia,  belong  to  the  first  or  smooth-skinned  group,  and  these 
may  be  contrasted  as  follows  : 

In  sub -genus  Lebertia  the  body  is  rather  elongate.  The 
second  pair  of  legs  is  without  swimming  hairs,  while  the  third 
and  fourth  pairs  have  only  isolated  ones  on  the  fourth  and  fifth 
segments.  The  number  of  these  swimming  hairs  on  each  segment 
varies — may,  indeed,  even  be  wanting — but  does  not  exceed  four. 
It  may  be  remarked  here  that  in  L.  subtilis  the  swimming  hairs 
appear  to  be  entirely  wanting.  The  third  and  fourth  segments 
of  the  palpi  are  each  fairly  uniform  throughout  their  length. 
The  third  segment  has  on  its  inner  surface  five  long  bristles ; 
three  of  these  are  distal,  the  middle  one  being  fairly  close  to  that 
at  the  edge  of  the  extensor  surface.  The  fine  pores  on  the  flexor 
surface  of  the  fifth  segment  are  not  very  distinct,  while  the  few 
small  hairs  on  the  extensor  surface  are  entirely  clustered  at  the 
distal  end,  one  or  two  isolated  ones  being  placed  rather  farther 
back.  By  Article  9  of  the  International  Rules  of  Zoological 
Nomenclature  (1905)  Neolebertia  is  suppressed  in  favour  of 
Lebertia  as  the  name  of  the  sub-genus. 

In  sub-genus  Pilolebertia  the  body  varies  from  oval  to  nearly 
circular  in  outline.  The  second,  third  and  fourth  pairs  of  legs 
have  numerous  swimming  hairs.  Contrasted  with  sub-genus 
Lebertia,  the  third  segment  of  the  palpi  is  more  like  an  inverted 
cone,  while  the  fourth  segment  is  rather  curved.  The  inner 
surface  of  the  third  segment  has  also  five  bristles ;  three  of  these 
are  distal,  the  middle  one  being  distant  from  the  edge  of  the 
extensor  surface,  not  close  to  it  as  in  Lebertia.  The  flexor 
surface    of    the   fourth    segment    has    two   distinct    pores    well 


THE    GENUS    LEBERTIA.  485 

separated,  while  all  the  small  hairs  on  the  extensor  surface  are 
distal. 

In  the  second  group  the  skin  is  either  not  dotted  over  with  fine 
pores,  or,  where  such  are  present,  they  are  indistinctly  seen  ;  but 
a  more  distinctive  feature  is  the  presence  of  papillae  or  of  ridges 
varying  in  length.  Species  which  are  apparently  smooth-skinned, 
but  belong  to  this  group,  may  be  distinguished  from  the  preceding 
group  by  the  presence  of  six  long  bristles  on  the  third  segment  of 
the  palpi  instead  of  five.  As  a  rule,  swimming  hairs  are  either 
quite  rudimentary  or  entirely  wanting,  but  in  some  species,  e.g. 
those  with  six  bristles  on  the  third  segment  of  palpi,  they  are  to 
be  found. 

Three  sub -genera,  Mixolebertia,  Pseudolebertia  and  Hexalebertia, 
belong  to  this  group. 

In  sub-genus  Mixolebertia  the  skin  may  be  papillose  or  finely 
granular,  finely  porose,  rarely  smooth.  Swimming  hairs  are 
generally  present.  The  inner  surface  of  the  third  segment  of  the 
palpi  possesses  six  long  bristles,  while  as  many  as  ten  spines 
may  be  found  on  the  extensor  surface  of  the  first  segment  of  the 
fourth  pair  of  legs. 

Pseudolebertia  and  Hexalebertia  have  certain  characters 
in  common,  in  that  they  possess  a  skin  which  is  apparently  not 
porose,  but  is  coarsely  papillated  or  covered  with  ridges  of  vary- 
ing length,  and  that  they  are  devoid  of  swimming  hairs ;  but 
otherwise  they  may  be  contrasted  as  follows  : 

In  sub-genus  Pseudolebertia  the  third  segment  of  the  palpi 
has  five  long  bristles,  of  which  three  are  towards  the  distal 
extremity.  One  or  two — more  rarely  three — of  the  fine  hairs 
on  the  extensor  surface  of  the  fourth  segment  are  more  proximal 
than  the  others.  The  anal  aperture  is  devoid  of  an  outer 
chitinous  ring. 

In  sub-genus  Hexalebertia  the  third  segment  of  the  palpi  has 
six  long  bristles.  The  fine  hairs  on  the  extensor  surface  of  the 
fourth  segment  are  grouped  about  the  distal  extremity.  The 
accessory  claw  and  lamina  at  the  distal  end  of  the  sixth  segment 
of  each  leg  are  sometimes  reduced  in  size.  Anal  aperture 
surrounded  by  a  chitinous  ring. 

Fortunately  material  was  available  to  enable  Sig  Thor  to  work 
out  the  nymphal  characteristics  of  the  sub-genera. 

In    sub-genus    Pilolebertia,    the   nymph  has   a   very  finely 


486     W.    WILLIAxMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

ribbed  skin  dotted  with  fine  pores.  The  epimeral  area  is  rela- 
tively broad,  with  the  provisional  genital  area  lying  well  within 
the  genital  bay.  The  two  long  bristles  on  the  extensor  surface 
of  the  third  segment  of  the  palpi  are  distal,  as  well  as  the  small 
hairs  on  the  extensor  surface  of  the  fourth  segment. 

Sub-genus  Lebertia  also  has  a  finely  ribbed  skin,  dotted  with 
fine  pores,  but  the  epimeral  area  is  relatively  narrower  and 
longer,  while  the  provisional  genital  area  is  set  well  back, 
sometimes  quite  outside  of  the  genital  bay.  Of  the  two  bristles 
on  the  extensor  surface  of  the  third  segment  of  the  palpi,  one  is 
about  the  middle  of  the  segment  and  the  other  distal. 

Sub-genus  Mixolebertia  has  the  skin  strongly  ridged  and  three 
bristles  on  the  third  segment  of  the  palpi. 

Sub-genus  Pseudolebertia  has  the  skin  ridged,  but  more 
sparingly  than  in  the  imago.  The  third  segment  of  the  palpi 
has  only  two  long  bristles. 

Sub-genus  Hexalebertia  has  the  skin  similar  to  Pseudolebertia, 
but  the  third  segment  of  the  palpi  has  three  long  bristles,  one  of 
these  being  much  more  proximal  than  the  others. 

Sig  Thor  has  also  proposed  to  establish  the  sub-genus  Duro- 
lebertia  to  cover  L.  solida,  but  as  that  species  appears  to  rest 
on  material  hot  too  well  preserved,  the  validity  of  Durolebertia 
must  remain  open  until  further  material  is  available  to  prove 
its  claims. 

It  may  be  here  observed  that  American  writers  do  not  appear 
to  favour  subdivisions  as  outlined  above. 

As  the  long  bristles  on  the  third  segment  of  the  palpi  are  an 
important  feature  in  the  imago,  the  position  of  these  on  the 
type  species  of  the  sub-genera  may  be  approximately  represented 
as  follows : 

< 

Lebertia.        Pilolebertia.  Mixolebertia.  Pseudolebertia.    Hexalebertia. 
L.  tau-inslgnita.    L.  insignis.    L.  brevipora.       L.  glabra.       L.  stigmatifera. 


•   •••  •••  •••  •••  ••• 

•  •  •  • 

•  •  • 


THE    GENUS    LEBERTIA.  487 

Between  seventy  and  eighty  species  with  varieties  have  been 
described.  The  species  described  here,  in  addition  to  the  sub- 
generic  types  (excluding  brevipora),  are  those  found  within  the 
Britannic  area. 

In  dealing  with  the  appendages  of  the  body,  it  is  generally 
found  convenient  to  designate  the  segments  by  number,  the  first 
being  invariably  that  which  is  articulated  to  the  body.  No 
terminology  has  yet  been  agreed  on,  though  Soar  *  and  Koenike  t 
have  discussed  the  matter. 

Lebertia  tau-insignita  (Lebert)  Sig  Thor. 
(Sub -gen.  Lebertia.) 

1879.  Pachygaster  tau-ivsignitus,  Lebert,  Bull.  Soc.  Vaud.,  xvi.  371. 
1905.  Lebertia  tau-insignita  (Lebert)  Sig  Thor,  Zool.  Anz.,  xxix. 
52-59,  figs.  18-24. 

This  species,  which  has  been  redescribed  by  Thor,  has,  so  far 
as  known  at  present,  a  restricted  range,  being  only  recorded 
from  the  neighbourhood  of  Morges  on  the  Lake  of  Geneva.  It 
is  the  type  species,  and  its  inclusion  here  is  therefore  appropriate. 
Thor  describes  the  body  outline  as  resembling  a  long  ellipse, 
whose  length  may  vary  from  O90  mm.  to  l-40  mm.  The 
greatest  breadth  ranges  from  0*80  mm.  to  l-05  mm.  The  venter 
is  weakly  arched,  the  dorsum  more  strongly  so.  The  anterior 
margin  of  the  body  between  the  antenniform  bristles  is  rounded, 
or  blunted.  In  this  it  differs  from  L.  fimbriata,  which  Thor 
selected  as  type  of  the  sub-genus  to  which  both  species  belong, 
as  well  as  with  regard  to  the  extent  to  which  the  anterior 
extremities  of  the  second  pair  of  epimera  extend  beyond  the 
body  margin  ;  in  the  case  of  the  present  species  they  do  not 
extend  much.  The  skin  is  smooth  and  very  finely  porose. 
Sometimes,  particularly  in  young  specimens,  the  skin  has  an 
extremely  fine  striate  appearance,  due  to  the  presence  of  very 
fine  folds.  These  are  in  no  way  comparable  to  the  coarse 
ridging  of  the  skin  such  as  may  be  observed  in  the  sub-genus 
Pseudolebertia,  but  Thor's  view  is  that  they  are  provision  for  the 
increase  in  size  of  the  body,  since  they  become  obliterated  as 
growth  proceeds.  The  colouring  is  unusual ;  it  is  almost  entirely 
blackish,  with  a  semi-transparent  yellowish  zone  round  the  edge 

*   Trans.  Edin.  Field  Nat.,  v.  375. 
f  Ahh.  Nat.  ver.  Bremen,  xx.  158. 


488     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

of  the  body.  On  the  dorsum  is  the  yellow  fam-shaped  (r)  figure 
indicating  the  organ  variously  designated  as  the  excretory  organ 
and  as  the  Malpighian  vessel.  The  dark  colour  of  the  venter  is 
relieved  by  white  and  yellow  specks.  The  legs  are  transparent 
and  tinged  with  green.  Thor  points  out  to  what  extent  the  colour 
of  the  body  responds  to  various  preservative  solutions,  and  the 
necessity  for  caution  in  identification  of  preserved  material  in 
those  cases  where  colour  may  be  of  some  value  in  assisting 
identification.  The  palpi  range  from  0*40  mm.  to  0*55  mm.  in 
length,  and  are  more  slender  than  the  first  pair  of  legs.  The 
second,  third  and  fourth  segments  are  covered  with  fine  pores 
clustered  together  in  groups,  which  are  distributed  fairly  evenly 
over  the  segments.  The  bristles  and  hairs  found  distributed 
over  the  segments  appear  to  be  fairly  constant  in  the  sub-genus 
to  which  our  species  belongs.  The  first  segment  has  only  one 
slightly  curved  bristle  at  the  distal  extremity  of  the  extensor 
surface.  The  second  segment  has  three  similar  ones  about 
the  middle  of  the  extensor  surface,  and  at  the  distal  extremity, 
but  just  towards  the  inner  side,  two  long  hairs  about  as 
long  as  the  third  segment.  The  long  bristle  at  the  distal  end 
of  the  ventral  or  flexor  surface  is  about  as  long  as  the  segment 
itself,  and  is  minutely  pectinate.  The  third  segment  has  five 
bristles,  two  about  the  middle,  close  to  the  extensor  surface,  and 
three  extremely  finely  pectinate  ones  at  the  distal  inner  sur- 
face, one  at  the  flexor  edge  and  two  at  the  extensor  edge.  The 
fourth  segment  has  five  fine  hairs  on  its  extensor  surface,  one 
in  the  posterior  one-third,  one  about  the  middle,  and  the  other 
three  scattered  about  the  distal  extremity.  The  flexor  surface 
has  only  one  pore  and  rudimentary  hair  in  its  distal  third. 
Concerning  the  function  of  the  long  flexor  bristle  of  the  second 
segment,  Thor  points  out  that  when  the  palp  is  flexed,  the 
bristle  can  enter  the  mouth  and  by  a  slight  lateral  movement 
can  also  enter  the  glandula  globulosa.  Thor's  conjecture  of  the 
function  may  be  expressed  thus — the  bristle  enters  the  pore  of 
the  glandula  globulosa,  and  by  means  of  the  pectination  some 
of  the  secretion  adheres  to  it.  The  secretion  may  then  be 
conveyed  to  the  claw  of  the  mandible,  and  thus  be  used  to 
paralyse  the  victim  whose  juices  are  to  be  extracted,  or  it  may 
be  conveyed  by  the  bristle  direct  to  the  wound  which  the  claw 
has  made. 


THE   GENUS    LEBSRTIA.  489 

The  epimera  form  a  shield  which  may  cover  from  one-half  to 
two-thirds  of  the  ventral  surface,  and  in  young  specimens  may 
even  go  as  far  as  four-fifths,  while  in  the  case  of  gravid  females 
the  proportions  may  be  entirely  reversed.      A  change  of  colour 
also  manifests  itself,  the  prevailing  tint  being  pale  blue  or  violet. 
The  inner  sutures  between  the  first  and  second  pairs  of  epimera 
do  not   extend  up  as   far  as  the  exterior  interval  between   the 
second  and  third   pairs,  and  in  this  respect  it  is  much   shorter 
than  Thor's  type  Jimbriata.     The  inner  end  of  the  second  pair  is 
scarcely  any  broader  than  Jimbriata.     The  lateral  expansions  of 
the  third  pair  are  large,  while  the  inner  ends  of  the  fourth  pair 
are  somewhat,  though  not  much,   broader  than  the  outer  ends. 
The  posterior  edges  of  the  epimera  are  not  so  thick  as  in  some 
species.     The  length  of  the  legs  appears  to  be  approximately,  first 
pair,  0"80  mm.  ;  second  pair,  0'90  mm.  to  1'10  mm.  ;  third  pair, 
1*25  mm.  ;  and  fourth  pair,  1*50  mm.  to  1*60  mm.      The  various 
segments  are  comparatively  long,  markedly  so  in  the  three  last 
segments  of  the  two  last  pairs  of  legs,  so  that  the  considerable 
length  of  the  legs  is  accounted  for.     The  terminal  segments  are 
not  so  robust. 

Thor  has  naturally  compared  the  armature  of  the  legs  of  this 
species   with  that   of   his   type  Jimbriata,  which   he   described  in 
detail.    Although  they  have  much  in  common,  certain  differences, 
especially  in  the  fourth  pair  of  legs,  are  to  be  found.     The  out- 
standing features    of    tau-insignita  are    as  follows  :    the    fourth 
segment  of  the  first  and  second  pairs  of  legs  has  two  or  three 
fine  long  bristles  on  the  extensor  surface.     The  third  pair  of  legs 
has    three    or    four    long    pectinate    bristles    on   the    outer    side 
of    the    third    segment ;    the   fourth    segment    has    five    bristles 
similar   to   those  of  the   first   and   second   pairs   of  legs,   and   is 
without  swimming  hairs.     The  fifth  segment  has  three  or  four 
shorter  bristles  standing  close  together,  and  has  two  swimming 
hairs  only.     The  greatest  divergence  is  exhibited  in  the  fourth 
pair  of  legs.     The  second  segment  has  two  or  three  short  bristles 
distal    on    the    extensor    surface.       The    third    segment    has  six 
pectinate  spines  ranged  round  the  distal  extremity.     The  fourth 
segment  has  six  spines  in  a  row  on  the  flexor  surface  and  one  on 
the  inner  surface.     All  are  rather  flattened   at  the    extremity. 
Six  are  pectinate,  and  swimming   hairs  are  also  wanting  here. 
The  fifth  segment  has  six  short  pectinate  spines  almost  in  a  row 
Journ.  Q.  M.  C,  Series  II. — No.  76.  34 


490     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

on  the  flexor  surface,  and  two  swimming  hairs  only.      The  small 
spines  of  the  sixth  segment  are  generally  six  in  number. 

The  genital  area  lies  about  one-fifth  of  its  length  out  of  the 
recess  or  bay  formed  by  the  inner  ends  of  the  epimera.      The 
genital  area  is  about   0*24  mm.  in    length,  and  at  its  broadest 
about  0*1 7  mm.      The  anterior  and  posterior  sclerites  for  muscle 
attachment  are  not  very  robust.     The  valves  are  about  0*22  mm. 
in  length,  and  have  five  pairs  of  coarse  pores  along  their  outer 
margins,  and  numerous  hair  pores  along  their  inner  edges.      The 
hairs  are  long,  reaching  almost  to  the  anus.     The  two  anterior 
pairs   of   acetabula    are    very   large,  the   posterior   pair   almost 
rectangular.      The  gland  pores  occupy  the  normal  position.     The 
anus  lies  about  midway  between  the  genital  area  and  the  posterior 
body  margin.     Sexual  dimorphism  appears  to  be  limited,  so  far 
as  external  appearance   is   concerned,   to    the   posterior   region 
of    the   genital   area   being  rather   wider  in   the   male   than   in 
the  female,  and  to  the  hair  pores  along  the  edge  of  the  genital 
valves  being  more  numerous,  viz.  twenty-four  to  twenty-eight  for 
the  male,  and  twelve  to  twenty  for  the  female. 

Nymph. 

Along  with  the  imaginal  forms,  Thor  obtained  two  nymphs, 
which  bear  so  close  a  resemblance  to  the  imago  of  this  species, 
that  he  was  constrained  to  accept  them  as  nymphs  of  tau- 
insignita.  The  body  in  comparison  is  rather  more  extended, 
and  is  0*68  mm.  in  length  and  0'43  mm.  in  breadth.  The  skin 
is  striate  and  minutely  porose.  The  structure  of  the  palpi  is 
very  much  as  in  the  imago,  but  the  equipment  of  hairs  is  very 
much  simpler.  The  hairs  are  confined  to  the  extensor  surface. 
The  first  segment  is  devoid  of  any  hairs.  The  second  has  one 
small  one  midway,  and  two  very  long  distal  ones  close  together. 
The  third  segment  has  one  long  distal  bristle  and  one  a  little 
way  behind  it.  The  fourth  segment  has  two  or  three  very  fine 
hairs,  of  which  one  is  well  back,  about  or  a  little  behind  the 
middle.  The  flexor  surface  resembles  that  of  the  imago.  The 
epimera  differ  from  the  adult  form  in  that  the  fourth  pair  has 
the  appearance  of  not  being  properly  developed.  The  posterior 
angle  has  a  little  papilla-like  projection.  The  legs  are  about 
0*38  mm.  long  in  the  first  pair  to  0*75  mm.  long  in  the  fourth 


THE    GENUS    LEBERTIA.  491 

pair,  and  have  only  from  one-third  to  one-half  the  nnmher  of 
hairs  and  spines  present  in  the  adult.  Only  one  or  two  swimming- 
hairs  are  to  be  seen.  The  provisional  genital  area  has  no  vulva, 
but  two  pairs  of  stipitate  acetabula,  surrounded  by  two  semi- 
circular chitinous  structures,  which  almost  meet  together  to  form 
a  circle. 

Lebertia  Soari  Sig  Thor. 

1905.  Sig  Thor,  Zool.  Anz.,  xxix.  55. 

This  species  must  be  rejected,  as  it  is  founded  on  a  diagram- 
matic representation  of  what  was  at  the  time  considered  to  be 
the  only  species  of  the  genus  (vide  Science  Gossip,  vi.  45,  and 
relative  figures). 

Lebertia  fimbriata  Si^  Thor. 
(Sub-gen.  Lebertia.) 

1839.  Lebertia  Jimbriata  Sig  Thor — En  ny  hydrachnide-slegt  og 
andre  nye  Arter — 0.  iVorli,  Kristiania,  p.  5.  PI.  xviii.  fig. 
172-175. 

1905.  Sig  Thor,  Zool.  Anz.,  xxix.  41-52,  figs.  5-17. 

This  hydracarid  is  of  a  dirty  yellow  colour,  which  is  somewhat 
masked  by  the  large  brown  patches  and  the  broad  pale-yellow 
strip  on  the  back.  It  appears  that  the  colour  is  apt  to  vary  a 
little.  The  legs  are  more  transparent  and  of  a  paler  colour  than 
the  body.  The  epimera  are  about  the  same  colour  as  the  body, 
but  more  iridescent.  The  body  is  soft  skinned,  without  any 
ridges  or  papillae,  and  has  scattered  over  it  many  fine  pores  which 
are  covered  externally  by  a  fine  membrane.  The  gland  pores, 
each  accompanied  by  its  fine  guard  hair,  lie  in  four  longitudinal 
rows  and  are  conspicuous  by  reason  of  the  strong  ring  which  sur- 
rounds each  of  them.  The  length  of  the  imago  varies  from  abou 
0*7  mm.  to  0'9  mm.,  and  if  the  anterior  tips  of  the  epimera  are 
included  may  even  reach  1  mm.  Viewed  dorso-ventrally  the 
outline  is  a  rather  elongate  ellipse,  which  is  indented  anteriorly 
between  the  antenniform  bristles.  The  dorsal  surface  is  arched 
very  much  more  than  the  ventral.  The  tips  of  the  first  two  pairs 
of  epimera,  each  with  a  long,  fine,  weakly  pectinate  hair,  are  very 
noticeable  beyond  the  anterior  end  of  the  body. 


492     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDKACARINA  : 

The  capitulum  is  rather  elliptical  in  shape.  Only  the  anterior 
half  is  visible,  the  posterior  half  being  concealed  behind  the 
epimera.  The  two  anterior  processes  are  long,  tapering  to  a 
sharp  point.  In  situ  they  are  directed  towards  the  posterior- 
dorsal  surface,  but  have  very  little  tendency  to  spread  apart 
laterally.  The  posterior  processes  are  very  much  shorter,  but 
similar  in  shape.  Their  direction,  however,  is  straight  into  the 
body,  so  that  they  partially  enclose  the  pharynx.  The  pharynx 
itself  is  fairly  wide  and  thick  and  increases  in  size  gradually 
towards  the  posterior  extremity.  The  mandibles  are  long  and 
slender,  extending  well  beyond  the  posterior  end  of  the  pharynx, 
and  work  in  a  furrow  formed  in  the  hinder  wall  of  the  capitulum. 
The  claws  are  very  nearly  straight  and  are  weakly  serrate. 
Opposed  to  the  claw  is  a  laminar  process  which  is  nearly  as  long 
as  the  claw. 

The  palpi  vary  in  length  from  0-35  mm.  to  0*40  mm.  The 
third  segment  is  shorter  than  the  second,  and  the  second  shorter 
than  the  fourth.  They  are  thinner  than  the  first  pair  of  legs 
and  are  laterally  compressed.  The  second  segment  has  a  long 
finely  pectinate  bristle  on  its  flexor  surface,  slightly  back  from 
the  distal  end.  On  the  inner  side  of  the  segment  almost  distal 
and  close  up  to  the  extensor  surface  there  are,  close  together,  two 
bristles  which  very  nearly  attain  the  length  of  the  third  segment. 
The  third  segment  has  five  weakly  pectinate  bristles  on  its  inner 
surface.  Of  these,  three  very  long  ones  are  at  the  distal 
extremity,  the  fourth  is  short  and  situated  close  to  the  extensor 
surface  and  slightly  behind  the  middle,  the  fifth  is  longer  than 
the  fourth  and  a  little  in  advance  of  it  and  rather  more  to  the 
inside.  The  three  distal  ones  are  generally  about  the  length  of 
the  fourth  segment ;  one  of  these  is  close  to  the  flexor  surface  and 
two  close  to  the  extensor  surface,  one  being  slightly  in  advance  of 
the  other. 

The  fourth  segment  has  only  one  small  pore  and  rudimentary 
hair  in  the  distal  third  of  the  flexor  surface.  The  extensor  surface 
has  five  or  six  fine  short  hairs  of  which  three  are  distal,  one  about 
midway  and  the  others  between. 

The  posterior  end  of  the  first  pair  of  epimera  lies  about  midway 
between  the  capitulum  and  the  genital  area.  The  posterior  end 
of  the  second  pair  is  fairly  broad.  The  suture  between  the 
second  and  third  pairs  extends  up  about  half-way  to  the  gland 


THE    GENUS    LEBERTIA.  493 

plate  on  the  outer  border  and  then  continues  as  a  filiform  exten- 
sion coming  well  up  towards  the  first  pair.  The  third  pair  is 
triangular  with  its  suture  extending  inwards  for  about  three- 
fourths  of  the  distance  to  the  genital  area.  The  fourth  pair  is 
also  three-sided,  the  outer  side  being  not  straight,  but  curving 
well  round  to  the  inner  posterior  corner.  The  epimera  are 
perforated  by  numerous  pores  which  are  visible  externally  as 
groups  of  fine  pores. 

The  legs  all  have  the  first  three  segments  short  and  the  la.st 
three  long,  and  in  addition  it  will  be  noted  that  the  terminal 
segments  are  rather  thicker  towards  the  distal  extremity.  The 
first  segment  of  all  pairs  of  legs  has  three  or  four  short  spines  on 
the  extensor  surface ;  in  the  case  of  the  second  and  third  pairs  of 
legs,  one  of  these  is  longer,  flattened  and  bipectinate ;  in  the 
fourth  pair  of  legs  the  segment  is  much  larger  than  in  the  others. 
The  second  and  third  segments  apparently  have  some  latitude  in 
their  equipment  of  spines,  but  the  distal  ends  have  one  or  two  of 
these  flattened  bipectinate  spines.  The  fourth  segment  of  the 
third  pair  of  legs  has  one  swimming  hair,  and  the  fifth  segment 
has  three.  The  fourth  segment  of  the  fourth  pair  of  legs  re- 
sembles that  of  the  third  pair,  while  the  fifth  segment  has 
two  or  three  swimming  hairs.  The  claws  have  a  short  thin 
lamina. 

The  genital  organ  is  pyriform  in  outline,  the  narrowed  anterior 
end  being  united  to  the  epimera  by  a  subcutaneous  chitinous 
strip.  Posteriorly,  the  genital  area  extends  for  about  one-third 
of  its  length  beyond  the  epimera  and  is  bounded  by  an  arc-shaped 
chitinous  ridge.  The  anterior  sclerite  is  short  and  thick.  The 
two  anterior  pairs  of  acetabula  are  roughly  rectangular,  with 
rounded  corners,  and  are  about  twice  as  long  as  broad.  The 
posterior  pair  are  more  nearly  round.  The  porose  covering  valves 
have  four  or  five  large  hair  ports  along  their  outer  edge,  and  along 
the  inner  edge  there  is  a  larger  number  of  fine  pores,  which  varies 
with  the  sex,  numbering  in  the  female  about  twelve  pairs  and  in 
the  male  about  twenty.  The  anal  orifice  lies  about  midway 
between  the  genital  area  and  posterior  body  margin. 

L.  jimbriata  has  been  taken  in  Surrey  and  Suffolk.  Halbert's 
fimbriata  of  the  Clare  Island  Survey  has  been  redescribed  as 
L.  celtica  Sig  Thor. 


494     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA.  : 

Lebertia  celtica  Sig  Thor. 
(Sub-gen.  Lebertia.) 

1911.  Lebertia  fimbriata  Halbert,    Proc.    Irish   Ac,    xxxi.   (39i) 

22,  plate  iii.  fig.   31. 
1911.  L.  celtica  Sig  Thor,  Zool.  Anz.,  xxxviii.  330. 

Two  specimens  were  taken  at  Clare  Island  and  recorded  as 
fimbriata.  From  the  short  note  and  figure  accompanying  the 
record  Sig  Thor  came  to  the  conclusion  that  these  were  sufficiently 
distinctive  in  character  to  warrant  a  new  species,  L.  celtica.  At 
first,  Thor's  new  species  did  not  seem  to  be  well  grounded,  and 
fimbriata  var.  celtica  appeared  to  be  better  able  to  meet  require- 
ments. Careful  examination  of  the  types,  however,  leads  to  the 
rejection  of  a  mere  variety  in  favour  of  celtica  n.sp.  In  support 
of  this  may  be  cited  the  elongate  body  form  and  relatively 
contracted  epimera,  and  the  skin  externally  smooth  but  with 
traces  of  ridges,  either  suppressed  or  of  a  rudimentary  type. 

The  body  is  about  0*9  mm.  long  and  0*6  mm.  broad.  The 
noticeable  feature  is  the  evenness  of  the  sides,  so  that  the  body 
is  of  about  the  same  width  throughout.  The  posterior  end  is 
rounded,  while  the  anterior  end  has  a  triple  indentation,  viz.  one 
at  each  of  the  corners  and  one  between  the  antenniform  bristles. 
The  colour  is  a  golden  brown,  with  dark  patches  on  the  dorsum. 
Legs  and  palpi  are  greyish.  Gland  pores  are  arranged  in  four 
rows  on  the  dorsum ;  each  pore  has  a  diminutive  guard  hair,  and 
is  protected  by  a  strong  ring.  The  capitulum  measures  about 
0*22  mm.  in  length,  and  the  mandibles  about  0*25  mm. 

At  present  details  as  to  the  capitulum  are  not  available,  but 
these  will  no  doubt  become  so  after  further  dissections  of  the 
type  have  been  made.  The  palpi  are  thinner  than  the  first  pair 
of  legs,  and  measure  about  0*27  mm.  in  length.  The  armature 
of  bristles  is  as  follows  :  on  the  extensor  surface  of  the  first 
segment  one  bristle,  and  on  that  of  the  second  segment  three 
short  and  two  long  ones  at  the  distal  end.  The  usual  long 
bristle  is  to  be  found  on  the  flexor  surface.  The  third  segment 
has  the  distal  extremity  rather  stouter  than  is  to  be  found  in 
fimbriata.  The  five  bristles  on  the  inner  side  occupy  practically 
typical  positions,  but  the  posterior  one  of  the  five  appears  to  be 
much  longer  than  the  corresponding  one  of  fimbriata.  The  flexor 
surface  of  the  fourth  segment  is  almost  straight,  and  has  only 


THE    GENUS    LEBERTIA.  495 

one  pore  in  the  distal  third  accompanied  by  a  diminutive  hair. 
The  extensor  surface  bulges  out  somewhat,  and  gives  the  im- 
pression of  a  flattened  arch.  It  has  only  one  short  hair  midway 
and  two  similar  distal  ones,  one  on  each  side.  The  fifth  segment, 
which  is  conical,  ends  in  three  claws,  of  which  the  back  one  is 
smaller  than  the  other  two.  The  pores  on  the  segments  are  not 
large,  but  they  are  fairly  evenly  distributed  right  up  to  the  distal 
end  of  the  fourth  segment. 

The  epimera  are  rather  long  in  comparison  to  the  breadth, 
bat  this  may  be  due  to  the  fact  that  the  sides  are  rather  drawn 
in  towards  the  body,  so  that  the  whole  epimeral  area  has  a 
slightly  arched  appearance.  Anteriorly  the  epimera  extend  well 
beyond  the  body  margin.  The  first  pair  of  epimera  extends 
posteriorly  to  half-way  between  the  capitulum  and  the  genital 
area.  The  posterior  ends  of  the  second  pair  are  broadened  out, 
and  the  suture  which  separates  them  from  the  other  pairs 
extends  well  up  and  tends  to  draw  in  towards  the  first  pair. 
The  suture  between  the  third  and  fourth  pairs  goes  well  on 
towards  that  of  the  second  pair,  so  that  the  third  has  an  almost 
triangular  appearance.  The  fourth  pair  also  may  be  described 
as  three-sided,  as  the  outer  side  sweeps  round  from  the  third 
pair  to  the  genital  area.  The  posterior  corner  in  one  of  the 
specimens  is  rounded,  in  the  other  it  is  truncated. 

The  first  pair  of  legs  measures  0  60  mm.,  the  second  pair 
0*67  mm.,  the  third  pair  0*74  mm.,  and  the  fourth  pair  0*87  mm. 
At  the  base  of  each  of  the  well-developed  claws  of  the  first 
two  pairs  of  legs  there  is  a  small  claw-like  process.  The  sixth 
segment  of  the  first  pair  of  legs  increases  in  thickness  towards 
the  distal  end,  and  is  coarsely  porose.  The  inner  surface  is 
without  hairs  or  spines.  The  fifth  segment  is  similar  in  size 
and  shape  to  the  foregoing,  and  has  only  one  flattened  spine 
and  two  or  three  short  hairs  at  the  distal  end.  The  fourth 
segment,  though  somewhat  similar,  is  rather  stouter.  The 
third  segment  is  shorter  and  stouter,  with  one  flattened  weakly 
pectinate  spine  and  three  or  four  short  ones  distal.  The  sixth 
segment  of  the  second  pair  of  legs  is  similar  to  that  of  the 
first  pair — it  is,  however,  a  little  longer  and  more  slender.  The 
fifth  segment  is  a  little  longer  than  the  sixth,  and  has  three 
or  four  short  spines  and  one  or  two  short  fine  hairs  at  the 
distal  end.     The  fourth  is  proportionately  longer  and  stronger 


496     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

than  the  foregoing,  and  has  six  or  seven  strong  spines  round 
the  distal  end  and  three  or  four  round  the  middle.  The  third 
segment  is  shorter  and  stouter,  and  has  five  or  six  spines  round 
the  distal  end  and  three  or  four  round  the  middle.  One  of  the 
distal  spines  is  more  like  a  bristle. 

The  third  pair  of  legs  has  one  short  fine  hair  on  the  distal  half 
of  extensor  surface  of  sixth  segment.  The  fifth  segment  has  one 
moderately  long  fine  distal  hair  and  one  or  two  short  spines 
about  midway.  The  fourth  segment  has  six  or  seven  spines  of 
varying  length  round  the  distal  end  and  four  or  five  round  the 
middle.  The  third  segment  has  four  or  five  spines  of  varying 
length  and  stoutness  round  the  distal  extremity,  and  a  similar 
number  of  shorter  ones  round  the  middle. 

The  sixth  segment  of  the  fourth  pair  of  legs  has  two  short 
spines  on  the  distal  half.  The  fifth  segment  has  two  moderately 
long  fine  swimming  hairs  and  five  or  six  short  thin  spines  at  the 
distal  end.  There  are  six  or  seven  short  thin  ones  on  the  inner 
edge  and  two  short  ones  on  the  outer  edge.  The  fourth  segment 
has  five  or  six  short  spines  along  the  inner  edge  and  four  on  the 
outer  side. 

The  valves  of  the  genital  area  lie  close  up  to  the  posterior 
ends  of  the  second  pair  of  epimera  and  extend  posteriorly  beyond 
the  epimera  for  about  one-fourth  of  their  length.  Along  the 
inner  edge  of  the  valves  there  are  about  seven  pairs  of  hair 
pores.  The  two  anterior  pairs  of  acetabula  are  long  and  narrow. 
The  posterior  pair  are  shorter  and  broader. 


Lebertia  insignis  Neuman. 
(Sub-gen.  Pilolebertia.) 

1880.    Lebertia  insignis  Neuman.      Kgl.  Sv.  Vet.   Akad.  HandL, 

xvii.  (3),  68-70,  pi.  viii.  fig.  4. 
1906.   Sig  Thor,  Zool.  Anz.,  xxix.  784-790,  figs.  50-53. 

Viewed  from  the  critical  standpoint  from  which  the  genus  is 
now  considered,  it  is  not  to  be  wondered  that  Neuman's  description, 
written  about  thirty-five  years  ago,  should  treat  rather  differently 
some  details  which  recent  writers  have  considered  of  some 
moment.  Any  doubts,  however,  which  might  have  arisen  as  to 
Neuman's   species   can  now  have    little   force,  as   Sig  Thor  has 


THE    GENUS    LEBERTIA.  497 

examined  Neuman's  type  specimen  and  supplied  what  was 
deficient  in  the  original  description. 

The  species  is  distinguishable  first  of  all  by  its  small  size, 
which  is  variable  and  may  range  from  about  0*8  mm.  in  length 
to  slightly  over  twice  that  size.  The  greatest  breadth  is  a  little 
under  that  figure.  As  a  rule  the  body  is  somewhat  dorso- 
ventrally  compressed  and  varies  from  a  broad  oval  to  nearly 
round.  The  anterior  is  without  any  weak  marginal  indent — 
rather  bluntly  rounded.  The  apical  extremities  of  the  first  and 
second  pair  of  epimera  extend  only  slightly  beyond  the  body 
margin. 

The  colour  may  be  a  reddish  brown  or  a  }'ello\vish  red  with 
large  brown  spots,  with  the  excretory  organ  showing  through  as 
a  broad  T-  or  Y-shaped  strip  on  the  dorsum.  The  epimera  have 
a  tinge  of  blue  or  green.  The  palpi  and  legs  may  also  have  these 
colours  or  even  a  bright  red,  but  in  these  appendages  the 
colours  are  fairly  transparent. 

Beyond  being  thinner,  the  skin  is  similar  to  that  of  porosa. 
The  capitulum  also  resembles  that  of  porosa,  but  it  is 
decidedly  smaller.  The  tapered  anterior  processes  are  of 
moderate  length  and  do  not  spread  out  very  much  laterally. 
While  the  mandible  closely  resembles  that  of  the  allied  species, 
it  is  also  more  symmetrical  in  its  build.  The  posterior  portion 
is  weakly  sinuate  with  the  extremity  sharply  turned  up.  The 
pharynx,  like  the  mandible,  is  also  more  symmetrical. 

The  palpi  appear  to  have  some  latitude  in  regard  to  their 
length,  as  the  extremes  of  0'30  mm.  and  0*48  mm.  have  been 
recorded.  The  Irish  specimens  are  even  larger,  viz.  0'52  mm. 
The  second  segment  has  five  or  six  bristles  on  the  extensor  surface, 
while  the  characteristic  bristle  on  the  flexor  surface  is  short,  and 
though  it  is  distinctly  back  from  the  distal  extremity  of  the  seg- 
ment, it  is  not  so  much  as  is  to  be  noted  in,  say  porosa  or  obscura. 
The  third  segment  has  five  long  finely  pectinate  bristles  on  the 
inner  side.  Three  of  these  are  close  to  the  extensor  edge.  The 
proximal  and  distal  ones  each  stand  slightly  back  from  their 
respective  ends  of  the  segment,  while  the  middle  one  is  more  on 
the  edge  than  the  other  two.  The  remaining  two  stand  close 
together  distally  almost  at  the  flexor  edge.  This  feature  rather 
marks  out  insignis  from  other  species  of  the  sub-genus.  While 
the  middle  one  of  the  three  distal  bristles  is  typically  towards  the 


498     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

flexor  surface,  this  appears  to  be  more  decidedly  shown  in 
insignis  (Thor's  two  figures  do  not  agree  as  to  this.  Of.  Zool. 
Anz.,  xxviii.  821,  fig.  1,  and  xxix.  788,  fig.  53).  All  the  short 
fine  hairs  on  the  fourth  segment  are  distal. 

The  epimera  are  relatively  larger  than  in  sub-genus  Lebertia. 
As  a  rule  the  breadth  is  greater  than  the  length.  The  lateral 
extensions  of  the  epimera  embrace  that  portion  of  the  sides 
abutting  on  the  epimera.  It  must  be  remarked  here,  however, 
that  these  extensions  can  only  be  observed  in  certain  positions 
if  the  creature  is  not  dissected.  In  preparations  where  the 
epimera  are  removed,  or  the  body  is  flattened  out,  the  extensions 
can  be  readily  seen.  The  first  pair  of  epimera  is  of  normal 
form.  The  second  pair  is  narrow  and  of  almost  uniform 
width  throughout.  If  the  suture  between  the  third  and  fourth 
pairs  were  continued  for  the  full  length,  it  would  just  about  meet 
the  inner  end  of  the  suture  between  the  second  and  third  pairs, 
showing  the  third  pair  to  be  almost  triangular  in  form.  The 
fourth  pair  is  broader  at  the  inner  end  than  at  the  outer. 
The  outer  edge  is  lightly  rounded. 

The  legs  measure  up  to  1*00  mm.  in  the  first  pair,  1*25  in  the 
second  pair,  1*70  mm.  in  the  third  pair  and  205  mm.  in  the 
fourth  pair.  The  fourth,  fifth  and  sixth  segments  of  each  pair 
of  legs  are  much  longer  than  the  other  segments.  The  sixth 
segment  of  the  second,  third  and  fourth  pair  of  legs  is  more 
or  less  thicker  at  the  distal  extremity  than  at  the  proximal.  The 
first  segment  of  the  fourth  pair  of  legs,  which  is  much  larger 
than  the  corresponding  segment  of  the  other  pairs,  has  on  its 
extensor  surface  one  or  two  small  proximal  bristles  and  distally 
two  much  longer  ones.  The  flexor  surface  has  one  distal  bristle 
with  two  accompanying  hairs.  The  flexor  surface  of  the  sixth 
segment  has  generally  only  three  spines.  The  swimming  hairs 
are  short,  relatively  few  and  variable  in  number.  The  fifth 
segment  of  the  second  pair  of  legs  may  have  from  five  to  seven. 
With  respect  to  the  third  and  fourth  pairs  of  legs,  the  fourth 
.segment  may  have  up  to  eight,  and  the  fifth  segment  up  to  twelve. 

The  genital  area  extends  a  little  beyond  the  epimera. 
Posteriorly  it  is  bounded  by  a  thick  chitinous  curving  ridge  and 
anteriorly  by  a  stellate  sclerite  which  forms  a  bridge  between  it 
and  the  epimera.  The  valves  and  acetabula  are  of  normal  form. 
Along  the  inner  edges  of  the  valves  there  are  a  number  of  hair 


THE    GENUS    LEBERTIA.  499 

pores,  ranging  in  the  female  up  to  sixteen,  and  in  the  male  up  to 
twenty-five. 

Nymph. 

The  nymphs  are  about  0*60  mm.  in  length  and  050  mm.  in 
breadth.  The  fifth  segment  of  the  second  pair  of  legs  has  two 
swimming  hairs.  The  fourth  segment  of  the  third  and  fourth 
pair  of  legs  has  only  two  swimming  hairs,  and  the  fifth  segment 
only  four  swimming  hairs.  The  flexor  surface  of  the  sixth 
segment  of  the  fourth  pair  of  legs  has  only  one  small  spine. 

This  species  has  been  found  in  Great  Britain  and  Ireland,  as 
well  as  Norway,  Sweden,  Finland,  Germany,  Switzerland  and 
Italy. 

Lebertia  vigintimacidata  Sig  Thor  is  now  considered  by  its 
author  to  be  merely  a  variety  of  the  above  and  other  species 
(vide.  Zool.  Anz.,  xxix.  786). 

Lebertia  porosa  Sig  Thor. 
(Sub-gen.  Pilolebertia.) 

1897.   L.  tau-insignita  et  insignis  Thor.    Ark.  Math.  Naturv.,  xix. 

(6)  31  ;  xx.  (3)  18. 
1900.  L.  porosa  Thor.     Nyt.  Mag.  Naturv.,  xxxviii.  273. 
1905.  Sig  Thor,  Zool.  Anz.,  xxix.  761. 

Lebertia  porosa  is  one  of  the  species  attaining  a  large 
size.  Considerable  variation  appears  to  exist  with  regard  to 
length,  as  specimens  have  been  recorded  from  0'9  mm.  up  to 
2-l  mm.,  with  a  corresponding  breadth  varying  from  0  85  mm. 
to  1'9  mm.  The  most  common  length  appears  to  be  about  1  mm. 
or  a  little  over,  and  the  breadth  about  01  mm.  less  than  the 
length.  The  body  is  oval  to  almost  round,  frequently  slightly 
dorso-ventrally  compressed.  The  anterior  end  is  rounded,  with 
the  apices  of  the  first  and  second  pairs  of  epimera  extending 
a  little  beyond  it.  The  colour  is  a  dark  reddish  brown  or  a 
yellowish  red  with  brown  spots,  with  the  excretory  organ  showing 
through  as  a  bright-yellow  T-shaped  dorsal  figure.  The  epimera 
may  show  a  faint  bluish  or  greenish  tinge,  while  the  palpi  and 
legs  are  more  transparent,  and  evidently  more  variable  as  to 
colour,  as  red,  green,  blue,  or  bluish  green  are  found.  Thor  has 
pointed   out   that   the   action   of    preservative  solutions  on  the 


500     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

colours  is  erratic.  Thus,  for  example,  of  two  specimens  subjected 
to  identical  treatment,  one  may  bleach  out,  while  the  other 
retains  its  colours,  or  all  or  part  of  the  dark  spots  may  remain 
while  the  rest  of  the  colour  may  fade.  Thor  conjectures  that 
the  condition  of  the  dermal  glands  may  have  some  bearing  on 
this  question.  The  skin  is  rather  thick,  smooth  and  strewn  over 
with  fine  pores. 

The  anterior  maxillary  processes  are  long  and  broad,  tapering 
to  a  point,  and  extend  in  an  upward,  lateral  direction  towards 
the  posterior,  but  not  so  far  as  to  meet  the  pharynx  or  the 
posterior  processes.  The  latter  have  their  extremities  curved 
upwards  so  as,  in  a  manner,  to  enclose  the  pharynx. 

The  palpi  are  laterally  compressed,  and  are  thinner  than  the 
first  pair  of  legs.  The  length  varies  from  04  mm.  to  0*6  mm. 
The  third  segment  is  always  shorter  than  the  second  and  fourth 
segments.  It  should  be  noted  that  compared  with  the  second 
and  third  segments,  the  pores  of  the  fourth  segment  are  much 
finer.  These  gradually  disappear  towards  the  distal  extremity, 
so  that  that  region  has  a  very  much  smoother  appearance.  The 
first  segment  has  only  one  short  slightly  curved  bristle  on  its 
extensor  surface,  where  the  second  segment  has  six  or  seven.  Of 
these  the  two  distal  ones  are  long  and  thin,  and  stand  back  from 
the  distal  extremity  of  the  segment.  The  characteristic  fine 
pectinate  bristle  on  the  flexor  surface  is  weak  and  not  particularly 
long,  being  generally  about  half  the  length  of  the  segment  or  a 
little  over  that.  The  third  segment  has  five  finely  pectinate 
bristles ;  one  of  these  is  proximal  and  close  to  the  second  segment, 
while  another  is  about  the  middle,  rather  more  on  the  extensor 
surface  than  on  the  inner.  These  two  are  generally  shorter  than 
the  other  three,  which  are  distal,  and  about  the  length  of  the 
fourth  segment.  The  middle  one  of  that  three  is  about  equi- 
distant from  the  one  on  each  side  as  in  obscura.  The  fourth 
segment  has  two  distinct  pores  on  its  flexor  surface,  each  with  a 
rather  rudimentary  hair.  One  of  these  pores  is  in  the  proximal 
third,  the  other  may  be  so  far  forward  as  to  be  in  the  distal 
third.  The  five  fine  hairs  on  the  extensor  surface  are  all  distal. 
The  fifth  segment  is  small,  almost  conical,  ending  in  two  small 
claws  lying  close  together,  with  a  small  one  behind  them. 

The  epimera  agree  very  closely  with  those  of  insignis,  with  the 
exception  that  the  inner  ends    of   the   second   pair   are    much 


THE    GENUS    LEBEliTIA.  501 

broader  in  porosa  than  in  ins  ignis.  The  inner  corners  of  the 
third  and  fourth  pairs  of  epimera  are  more  rounded,  not  so 
acute  as  in  insignis.  All  the  sutures  and  margins  are  thick, 
the  inner  ones  particularly  so. 

Some  variation  appears  to  manifest  itself  with  regard  to  the 
length  of  the  legs,  but  in  general  it  may  be  said  that  the  two 
anterior  pairs  of  legs  are  short,  and  that  the  two  posterior  pairs 
attain  something  like  the  length  of  the  body  or  a  little  over. 
The  sixth  segments  are  either  weakly  thickened  or  not  at  all. 
The  sixth  segment  of  the  first  pair  of  legs  is  not  thickened, 
but  reduced  in  length.  The  thickening  of  the  corresponding 
segment  of  the  second  pair  of  legs  is  scarcely  appreciable,  more 
so,  however,  in  that  of  the  third  and  fourth  pairs  of  legs.  The 
first  three  segments  of  each  pair  of  legs  are  the  shortest,  the 
other  three  the  longest.  In  comparing  the  first  segment  of  each 
pair  of  legs,  it  will  be  noticed  that  that  of  the  fourth  pair  of  legs 
is  by  far  the  longest.  Swimming  hairs  are  entirely  wanting  in 
the  first  pair  of  legs.  The  second  pair  has  a  small  group 
clustered  at  the  distal  end  of  the  fifth  segment ;  these  are  not  so 
long  as  the  succeeding  segment.  The  third  pair  has  five  to  ten 
long  swimming  hairs  at  the  distal  end  of  the  fourth  segment,  and 
eight  to  fifteen  at  the  end  of  the  fifth  segment.  The  fourth  pair 
of  legs  has  five  to  nine  long  hairs  at  the  distal  end  of  the  fourth 
segment,  and  anything  from  eight  to  seventeen  at  the  end  of  the 
fifth  segment.  The  claws  appear  to  be  of  normal  form,  a  large 
thin  claw  with  a  thin  broad  laminate  base,  and  in  the  narrow 
interval  between  a  small  accessory  claw. 

The  genital  area  is  fairly  typical  in  form,  and  extends  but 
little  beyond  the  epimera.  The  male  is  distinguishable  from  the 
female  by  the  greater  breadth  posteriorly  in  the  valves  and  by 
the  number  of  gland  hairs  along  the  inner  margins,  viz.  twenty 
to  thirty-three  where  the  female  has  only  from  fourteen  to 
twenty.  The  large  pores  along  the  outer  margin  are  few  in 
number,  not  more  than  five  pairs  at  the  most.  Of  the  sclerites 
which  serve  for  muscle  attachment,  the  anterior  one  is  triangular 
in  shape,  with  its  apex  continued  into  a  narrow  bridge  to  bind 
it  to  the  epimera.  The  posterior  one  is  broad  and  porose,  and 
is  more  like  a  semicircle  in  outline.  The  two  anterior  pairs  of 
acetabula  are  long  and  narrow,  rather  rectangular,  with  rounded 
corners.      The  posterior  pair  is  much  shorter  and  broader. 


502     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

Nymph. 

The  nymph  is  about  0*70  mm.  in  length  and  about  0*65  mm. 
in  breadth.  The  palpi  are  pretty  much  like  those  of  the  imago 
so  far  as  the  structure  is  concerned,  but  in  re&pect  to  the  number 
and  arrangement  of  the  bristles  there  is  a  marked  difference. 
The  first  segment  has  none  at  all  ;  the  second  has  two  on  the 
extensor  surface  and  one  distal.  The  third  segment  has  only 
two  long  bristles,  both  distal,  one  on  the  extensor  surface  and 
one  midway  on  the  inner  surface.  The  distal  extensor  surface  of 
the  fourth  segment  has  only  three  short  ones,  in  other  respects 
it  resembles  the  imago.  The  provisional  genital  area  does  not 
extend  beyond  the  epimera.  The  surrounding  ring,  which  is  in 
communication  with  the  epimera  anteriorly  by  a  small  sclerite, 
has  about  six  fine  pores.     The  four  acetabula  are  stijDitate. 

Var.  britannica  Sig  Thor  covers  some  British  specimens  which 
have  the  posterior  pair  of  acetabula  about  the  length  of  the 
second  pair  instead  of  much  shorter  as  is  usually  the  case  (Zool. 
Anz.,  xxix.  776). 

Var.  vigintimaculata  Sig  Thor  has  presumably  the  same 
characteristics  as  the  variety  of  the  same  name  under  L.  insignis 
(ib.  786). 

Var.  dorsalis  Sig  Thor  has  the  middle  distal  bristle  of  the 
inner  surface  of  third  segment  placed  more  towards  the  extensor 
surface  (ib.  779). 

Var.  italica  Sig  Thor.  Specimens  from  Lake  Maggiore  have 
the  legs,  epimera  and  palpi  of  a  decided  greenish -blue  colour 
(ib.  779). 

These  latter  forms  are  evidently  local,  but  it  is  open  to  ques- 
tion whether  they  have  sufficient  claim  to  be  ranked  as  varieties. 

Lebertia  porosa  has  been  recorded  for  Britain  and  appears  to 
have  a  fairly  wide  distribution,  as  even  Siberia  has  added  its 
quota  to  the  recorded  distribution. 

Larva. 

The  outline  is  approximately  oval,  and  measures  about 
0*3  mm.  in  length  and  0'2  mm.  in  breadth.  The  body  is  dorso- 
ventrally  compressed,  and  this  applies  particularly  to  the  posterior 
region.  The  dorsum  and  venter  are  both  protected,  the  former 
by  a  chitinous  plate,  which  extends  nearly  to  the  edge  of  the 


THE    GENUS    LEBERTIA.  503 

body,  and  the  latter  by  the  epimeral  plate,  which  is  similar  in 
size  to  the  dorsal  plate.  The  skin  of  the  lateral  surface  between 
the  edges  of  the  plates  is  soft  and  marked  by  tine  lines  running 
the  length  of  the  body.  Along  this  area  dorsally  there  are  nine 
pairs  of  long  stiff  bristles  in  two  rows,  an  inner  of  four  pairs  and 
an  outer  or  more  lateral  one  of  five  pairs.  The  dorsal  plate  has 
three  pairs — two  pairs  lying  close  -3  front  of  the  eyes  and  a 
small  pair  representing  the  antenniform  bristles.  The  ventral 
surface  also  has  a  few  hairs — two  pairs  on  or  near  the  edge 
of  the  epimeral  plate  posteriorly  being  pectinate.  Quite  a 
number  of  these  hairs  may  extend  beyond  the  margin  of  the 
body. 

The  capitulum  is  about  0-0S  mm.  long.  It  extends  well  beyond 
the  bay  formed  by  the  first  pair  of  epimera,  and  curves  well 
towards  the  ventral  surface.  About  midway  up  each  side  the 
palpi  are  articulated.  The  third  and  fourth  segments  are  pro- 
minent by  reason  of  their  stoutness.  The  third  segment  has  one 
strong  bristle  on  its  outer  side,  while  the  fourth  has  a  moderately 
long  curved  claw.  The  fifth  segment  is  of  a  rudimentary  type  : 
it  lies  somewhat  recessed  into  the  fourth  segment,  and  has  two 
long  and  three  short  hairs  springing  from  it. 

The  larva  possesses  only  three  pairs  of  legs,  which  are  grouped 
well,  towards  the  anterior  end  of  the  body.  The  first  pair  may 
measure  up  to  0*20  mm.,  the  second  pair  027  mm.,  and  the  third 
pair  0*30  mm.  Swimming  hairs  are  entirely  wanting,  but  loco- 
motion is  aided  by  a  varying  number  of  moderately  long,  simple 
or  weakly  pectinate  straight  bristles,  which  are  to  be  found  in 
greatest  abundance  on  the  third  pair  of  legs.  Each  leg  ends 
in  three  fine,  long,  curving  claws,  of  which  the  middle  one  is  the 
smallest. 

Corresponding  to  the  number  of  pairs  of  legs,  there  are  only 
three  pairs  of  epimera.  The  suture  dividing  those  of  one  side 
from  the  other  is  well  marked,  as  well  as  that  dividing  the  first 
pair  from  the  second.  Only  a  very  short  rudimentary  lateral 
suture  separates  the  second  pair  of  epimera  from  the  third.  The 
posterior  portion  of  the  third  pair  is  cut  away  obliquely  on  the 
median  line  ;  within  this  recess  there  is  a  small  weakly  chitinised 
post-epimeral  plate,  which  Piersig  called  the  anal  plate,  but 
which  Thor  prefers  to  consider  as  the  rudiment  of  the  provisional 
genital  area  found  in  the  nymph. 


504     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  I 

Lebertia  obscura  Sig  Thor. 
(Sub-gen.  Pilolebertia.) 

1900.   Lebertia  porosa  var.  obscura  Sig  Thor.     Nyt.  Mag.  Naturv., 

xxxviii.  273,  pi.  x.  figs.  3  and  4. 
1902.  L.  obscura  Sig.  Thor  in  Arb.  Inst.  Wien,  xiv.  (2)  11,  pi.  i. 

fig.   9- 
1906.  Sig  Thor,  Zool.  Anz.,  xxix.  780,  figs.  47-48-54. 

Lebertia  obscura  was,  by  reason  of  its  closeness  to  L.  porosa, 
first  considered  by  Thor  to  be  only  a  variety  of  that  species,  but 
his  exhaustive  investigations  on  the  genus  led  him  to  elevate 
obscura  to  the  rank  of  a  distinct  species.  When  obscura  and 
porosa  are  contrasted,  it  will  be  noted  that  the  former  is  some- 
what the  larger  of  the  two,  ranging  from  1*5  mm.  to  2 "5  mm.  in 
length,  and  in  general  it  appears  to  be  of  a  more  robust  build  and 
somewhat  darker  colour. 

The  palpi  measure  up  to  about  0'65  mm.  in  length,  and  viewed 
ventrally  are  scarcely  so  stout  as  the  first  pair  of  legs.  Compared 
with  porosa  the  long  bristle  on  the  flexor  surface  of  the  second 
segment  is  relatively  shorter  and  situated  rather  more  distally, 
the  third  segment  is  shorter  in  proportion,  while  the  fourth  is 
broader  and  straighter,  with  the  two  pores  on  the  flexor  surface 
frequently  situated  close  together.  As  a  general  rule  the  fifth 
segment  is  shorter  and  more  blunted. 

The  legs  are  thick  and  strong.  The  first  pair  measures  about 
0*96  mm.,  the  second  pair  about  1*36  mm.,  the  third  pair  about 
1*70  mm.,  and  the  fourth  pair  about  1*92  mm.  in  length.  The 
fourth  pair  is  to  be  noted  as  possessing  in  the  fifth  and  sixth 
segments  a  larger  number  of  spines  and  swimming  hairs  than  in 
the  closely  allied  species,  and  also  what  Thor  deems  a  characteristic, 
the  possession  of  5  or  6  spines,  3  or  4  of  these  being  distal,  on  the 
extensor  surface  of  the  first  segment,  instead  of  the  3  (more  rarely 
4),  2  of  them  being  distal,  generally  associated  with  other  Pilo- 
lebertia species. 

L,  obscura  does  not  appear  to  be  a  widely  distributed  species, 
as  so  far  it  has  only  been  reported  from  Norway,  Scotland  and 
England. 


THE    GENUS    LEBERTIA.  505 

Lebertia  Halberti  Koen. 

(Sub-gen.  Mixolebertia.) 

1902.  Lebertia  Halberti  Koenike,  Zool.  Anz.,  xxv.  610. 

This  species  was  taken  by  Halbert  at  Dartrey  in  Ireland 
in  1899,  and  so  far  only  the  male  appears  to  be  known.  In 
outline  the  body  is  oval,  being  about  1*36  mm.  in  length  and 
about  1*20  mm.  at  its  broadest  part.  The  colour  of  the  body  is 
a  dark  green — described  by  Koenike  as  a  greenish  grey — the 
dorsal  surface  being  adorned  on  each  side  of  the  median  line  by  a 
row  of  roundish  dark  spots.  As  is  not  uncommon,  the  colour  of 
the  limbs  and  palpi  is  much  weaker  than  that  of  the  body.  The 
skin  is  without  the  strong  ridges  noticeable  in  other  species,  but, 
notwithstanding,  it  is  adorned  by  fine  lines  crossing  one  another 
as  to  form  an  elongated  mesh  work. 

The  palpi  are  0'43  mm.  in  length,  the  segments  being  respec- 
tively 0-04,  0-10,  0-10,  0-16  and  0'03  mm.  in  length,  and  in  their 
bristle  armature  they  closely  follow  the  type.  The  first  segment 
has  one  short  distal,  slightly  curved  spine  on  the  extensor  surface. 
The  second  segment  has  two  similar  but  rather  larger  spines 
on  the  middle  of  the  extensor  surface,  and  on  the  distal  inner 
surface  adjacent  to  the  extensor  surface  two  moderately  long 
bristles.  The  distal  flexor  surface  is  armed  with  the  usual  long 
bristle.  A  noticeable  feature  is  the  presence  of  six  bristles,  extend- 
ing nearly  to  the  distal  end  of  the  fourth  segment,  on  the  inner 
surface  of  the  third  segment.  Three  of  these  are  distal,  one  being 
adjacent  to  the  flexor  surface  and  the  other  two  close  up  to  the 
extensor  surface,  one  being  practically  on  the  extensor  surface.  Of 
the  other  three,  one  is  proximal,  while  the  remaining  pair  is 
situated  about  midway  and  occupies  about  the  same  position 
as  the  pair  anterior  to  it,  if  anything  rather  more  towards  the 
extensor  surface.  The  fourth  segment  has  four  fine  hairs  grouped 
at  the  distal  extensor  extremity.  The  posterior  of  the  two  pores 
on  the  flexor  surface  is  accompanied  by  the  typical  moderately 
long  hair. 

The  lateral  processes  at  the  anterior  end  of  the  capitulum 
have  very  little  tendency  to  spread  out  laterally — they  extend 
inwards  until  their  extremities  are  about  in  line  with  the  base 
of  the  posterior  pair.  The  claws  of  the  mandibles  have  a  row 
of  fine  teeth  on  their  concave  side. 

Joirax.  Q.  M.  C,  Series  II.— No.  76.  35 


506     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

The  legs  are  rather  more  slender  than  in  L.  insignis,  and  this 
may  be  attributed  to  the  fact  that  the  fourth,  fifth  and  sixth 
segments  of  the  second,  third  and  fourth  pairs  of  legs  are 
decidedly  longer.  The  fifth  segment  of  the  second  pair  of  legs 
has  swimming  hairs,  the  length  of  which  about  equals  that  of 
the  segment  itself. 

The  inner  posterior  ends  of  the  second  pair  of  epimera  just  in 
front  of  the  genital  valves  are  decidedly  thickened,  and  are  about 
twice  as  broad  as  in  L.  insignis.  The  fourth  pair  of  epimera  is 
nearly  of  equal  width  throughout,  any  tendency  to  increase 
manifesting  itself  towards  the  inner  end,  where  the  posterior 
corner  is  broadly  rounded  off. 

The  genital  area  extends  for  about  one-third  of  its  length 
outside  the  bay  formed  by  the  fourth  pair  of  epimera.  The 
thick  chitinous  ridge  which  forms  the  posterior  boundary  of  the 
area  lies  close  in  and  extends  a  little  way  up  the  sides.  The 
third  pair  of  acetabula  is  very  little  shorter  than  the  other  two 
pairs.  A  few  hairs  may  be  noted  along  the  posterior  margins 
of  the  valves. 

Lebertia  glabra  Sig  Thor. 
(Sub-gen.  Pseudolebertia.) 

1897.  Lebertia  glabra  Sig  Thor,  Arch.  Math.  Naturmd.,  xx.  (3), 

19,  pi.  iii.  fig.  23. 
1907.  Sig  Thor,  Zool.  Am.,  xxxi.  105-115,  figs.  73-81. 

Lebertia  glabra  appears  at  present  to  be  limited  to  Norway 
and  Scotland.  It  belongs  to  the  smaller  species,  and  appears  to 
vary  from  about  0'6  mm.  to  1*1  mm.  in  length,  and  about 
0'5  mm.  to  1*0  mm.  in  breadth.  In  outline,  the  body  presents 
a  somewhat  rounded  appearance,  and,  viewed  from  the  side,  the 
venter  is  seen  to  be  much  less  arched  than  the  dorsum.  The 
dorsal  surface  is  of  a  brownish -yellow  colour  with  dark-brown 
patches,  and  is  rendered  conspicuous  by  the  pale-yellow  T-shaped 
figure  of  the  excretory  organ  showing  through.  The  ventral 
surface  and  the  legs  have  a  tinge  of  green  in  their  colouring. 
The  skin  is  covered  with  short  chitinous  ridges,  some  of  which 
may  even  be  forked.  On  the  dorsal  surface  these  are  quite  short 
and  lie  more  or  less  parallel  to  the  long  axis  of  the  body.  On 
the  ventral  surface  they  are  longer  and  run  transversely.     In 


THE    GENUS    LEBERTIA.  507 

proximity  to  the  epiinera,  genital  and  anal  areas  the  ridges  to 
some  extent  follow  the  outline  of  these  more  highly  chitinised 
structures.  The  skin  would  appear  to  be  thin,  as  Thor  has 
been  unable,  except  in  isolated  cases,  to  detect  the  groups  of  fine 
pores  which  are  prominent  in  other  species,  though  the  epimera, 
genital  valves,  legs  and  palpi  exhibit  the  coarsely  porose  appear- 
ance to  be  found  throughout  the  genus. 

The  capitulum  is  of  the  form  normal  to  the  genus,  and  is  about 
0*22  mm.  in  length,  with  a  breadth  of  nearly  0*12  mm.  It  does 
not  fully  take  up  the  area  bounded  by  the  inner  margins  of  the 
first  pair  of  epimera.  While  the  anterior  processes  of  other 
species  have  an  upward  and  outward  tendency,  i.e.  towards  the 
interior  of  the  body,  in  this  species  they  are  more  slender  and 
come  closer  in  to  the  capitulum,  lying  more  in  a  horizontal 
direction  and  less  towards  the  interior  of  the  body.  The  posterior 
processes  are  fairly  slender.  The  mandibles,  like  the  anterior 
processes,  are  more  drawn  in  towards  the  capitulum  than  is 
usually  the  case.  They  are  fairly  long,  and  extend  beyond  the 
pharynx  and  the  extremities  of  the  anterior  processes.  An 
average  length  for  the  palpi  would  appear  to  be  slightly  over 
one-third  of  a  millimetre.  The  fourth  segment  is  longer  and 
thinner  than  the  two  preceding  ones,  while  the  fifth  is  relatively 
long  and  thin  and  tapered.  The  extensor  surface  of  the  first 
segment  has  one  long  fine  bristle.  The  corresponding  region  of 
the  second  segment  has  four  bristles,  of  which  the  two  longest 
are  almost  distal,  while  on  the  flexor  surface,  set  well  back  from 
the  distal  extremity,  there  is  a  strong,  curving  bristle,  which  is 
moderately  long  and  finely  pectinate.  The  inner  surface  of  the 
third  segment  has  five  bristles ;  three  of  these  are  distal,  finely 
pectinate,  and  about  as  long  as  the  fourth  segment.  The  middle 
one  of  the  three  lies  rather  more  towards  the  bristle  at  the 
extensor  edge,  which  happens  to  be  a  little  less  distal  than 
its  companions.  The  fourth  bristle  lies  about  the  middle  at 
the  extensor  edge  of  the  segment,  while  the  fifth  lies  slightly 
behind  it  and  rather  more  inwards.  The  distal  extensor  surface 
of  the  fourth  segment  has  six  hairs  of  varying  length  ;  five 
of  these  are  more  or  less  grouped  about  the  distal  extremity, 
but  the  sixth  lies  farther  back.  The  flexor  surface  has  the 
usual  two  fine  pores  with  accompanying  diminutive  hairs;  one  of 
these  pores  lies  about  the  middle,  the  other  one  is  nearly  proximal. 


508     W.    WILLIAMSON    AND   C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

The  epimera  are  about  as  broad  as  long,  a  trifle  over  0*7  mm. 
The  lateral  expansions  are  well  developed,  and  the  sutures  between 
the  epimera  are  very  thick.  This  applies  also  to  the  posterior 
margins,  which  are  rather  broader  than  usual.  The  inner  edge 
is  nearly  straight,  having  a  clean-cut  appearance.  The  width 
of  the  fourth  pair  is  nearly  equal  throughout,  the  outer  edge 
having  -<>  ''times  a  slight  concavity  near  the  gland  pore,  at 
other  times  it  is  slightly  rounded.  The  point  where  the  fourth 
pair  of  legs  articulates  with  the  epimera  lies  well  in  from  the  edge 
of  the  latter,  so  that  about  two-thirds  of  the  first  segment  of  the 
leg  lies  over  the  lateral  expansion.  The  recess  for  the  capitulum 
is  about  the  same  length  as  that  for  the  genital  area,  but  the 
latter  widens  out  posteriorly. 

The  legs  are  of  normal  structure,  and  in  the  case  of  the  third 
and  fourth  pairs  may  attain  to,  or  even  slightly  exceed,  the 
length  of  the  body.  The  terminal  segments  of  the  second,  third 
and  fourth  pairs  are  distinctly  enlarged  towards  their  extremities, 
but  in  the  case  of  the  corresponding  segments  of  the  first  pair, 
if  the  enlargement  exists,  it  is  only  weakly  developed.  None  of 
the  legs  have  swimming  hairs. 

The  genital  area  is  about  0'23  mm.  in  length  and  about 
0'15  mm.  in  breadth,  and  extends  for  about  a  fourth  of  its 
length  beyond  the  epimera.  The  lunate  plates  for  muscle 
attachment  which  lie  at  each  end  of  the  genital  area  are  fairly 
well  developed.  Along  the  inner  edge  of  each  of  the  valves, 
there  are  a  number  of  hair  pores.  The  acetabula  are  of  normal 
form,  and  decrease  slightly  in  size  from  the  anterior  pair  to 
the  posterior  pair.  The  anus  is  only  weakly  chitinised,  and  is 
without  the  strong  ring  observable  in  some  other  species. 

Externally,  the  sexes  appear  to  be  hardly  distinguishable  from 
one  another. 

Nymph. 

Thor's  observations  on  the  nymph  may  be  summarised  as 
follows.  The  length  ranges  from  0'43  mm.  to  0-55  mm.,  and  the 
breadth  from  035  mm.  to  0'48  mm.,  so  that  the  outline  may 
vary  from  oval  to  nearly  round.  The  colour  is  about  that  of  the 
imago,  though  sometimes  it  may  be  brighter  and  more  trans- 
parent. The  skin  is  thin  and  ridged  as  in  the  imago.  In  the 
nymph,  however,  the  ridges  are  smaller  and  not  so  abundant  as 


THE    GENUS    LEBERTIA.  509 

in  the  imago,  the  intervals  being  twice  as  great  as  in  the  latter. 
Any  fine  pores  which  may  be  present  are  extremely  difficult  to 
detect.  The  capitulum  and  the  epimera  resemble  those  of  the 
adult  form. 

The  palpi  are  about  0'22  mm.  in  length.  The  first  segment  is 
devoid  of  bristles.  The  second  segment  has  one  or  two  bristles 
distal  and  one  about  the  middle  of  the  extensor  surface.  The 
third  segment  has  two  rather  long  distal  bristles,  one  at  the 
extensor  surface  and  the  other  about  midway  on  the  inner 
surface.  The  fourth  segment  has  the  usual  two  pores  on  the 
flexor  surface. 

The  legs  are  about  0*40  mm.  long  for  the  first  pair;  0*45  mm. 
for  the  second  pair  ;  0'52  mm.  for  the  third  pair,  and  068  mm. 
for  the  fourth  pair.  The  terminal  segments  of  the  second, 
third  and  fourth  pairs  are  like  those  of  the  adult.  Swimming 
hairs  are  also  wanting. 

The  provisional  genital  area  has  four  acetabula  surrounded 
by  a  chitinous  ring,  which  is  open  towards  the  posterior  and 
anteriorly  is  attached  to  the  ligulate  muscle  attachment  plate. 

The  larval  stages  are  at  present  unknown. 

Lebertia  stigmatifera  Sig  Thor. 
(Sub-gen.  Heocalebertia.) 

1900.  Lebertia  stigmatifera  Sig  Thor    Nyt.   Mag.  for  Naturvid., 

xxxviii.  275-276,  pi.  xi.  figs.  7-9. 
1907.  Zool.  Anz.,  xxxii.  150-157,  figs.  87-90. 

Lebertia  stigmatifera  was  taken  by  Mr.  Deeley  in  Worcester- 
shire. It  is  here  recorded  as  an  addition  to  the  fauna  of  the 
Britannic  area,  and  is  another  link  in  the  chain  connecting  the 
Scandinavian  and  British  faunas.  It  belongs  to  the  smaller 
species,  a  common  size  being  about  0'7  mm.,  though  extremes 
of  0'58  mm.  to  1*05  mm.  have  been  recorded. 

The  body  is  very  nearly  circular  in  outline,  with  the  anterior 
margin  rather  flattened.  The  ground  colour  of  the  body  is 
yellow,  with  large  brown  patches  and  the  usual  T-shaped  yellow 
outline  on  the  dorsum.  The  skin  is  comparatively  thin,  and  is 
adorned  with  chitinous  ridges,  for  the  most  part  lying  parallel  to 
one  another.  The  skin  is  very  indistinctly  porose ;  in  the  case 
of  the  more  heavily  chitinised  parts,  the  common  large  pores  are 


510     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

to  be  found.  The  second  and  third  segments  of  the  palpi  show 
the  usual  groups  of  fine  pores,  but  in  the  fourth  segment  these 
gradually  disappear  towards  its  distal  extremity. 

The  capitulum  is  of  normal  form,  but  rather  small,  as  it  does 
not  quite  take  up  the  bay  formed  by  the  first  pair  of  epimera. 
The  posterior  processes  are  short  and  thick.  The  mandibles 
are  slender  in  structure,  and  about  a  quarter  of  a  millimetre 
in  length. 

The  palpi  are  about  0'4  mm.  in  length,  and  more  slender  than 
the  first  pair  of  legs.  The  fourth  segment  is  distinctly  longer 
than  the  third,  and  not  quite  so  stout.  The  first  segment  has 
only  one  fine  bristle  on  its  extensor  surface.  The  second 
segment  is  porose,  and  has  four  or  five  short  bristles  on  its 
extensor  surface.  The  characteristic  bristle  on  the  flexor  surface 
is  nearly  straight  and  very  slightly  pectinate.  It  stands 
distinctly  back  from  the  distal  edge.  The  third  segment  is 
also  porose,  and  carries  the  characteristic  of  the  sub-genus, 
namely,  six  long  bristles  on  the  inner  surface  of  the  segment. 
Of  the  three  which  are  almost  distal,  two  are  close  to  the 
extensor  surface.  The  fourth  is  not  quite  proximal,  and  is  close 
to  the  extensor  surface  also.  The  remaining  two  are  just  a 
little  posterior  to  the  middle  line — one  is  at  the  extensor  surface 
and  the  other  just  inside  of  it.  All  the  bristles  are  very  long, 
some  going  beyond  the  distal  end  of  the  fourth  segment.  The 
fourth  segment  is  weakly  porose,  and  it  should  be  noted  that  the 
two  fine  pores  on  the  flexor  surface  are  very  close  to  one  another 
and  the  accompanying  hairs  are  very  short.  The  rest  of  the  fine 
hairs  are  grouped  distally.  The  fifth  segment  is  very  short 
and  tapered. 

The  epimera  are  of  unusual  size  and  possess  an  extension  laterally 
and  posteriorly  which  forms  quite  a  characteristic  feature,  and  is 
apparently  most  marked  in  the  male.  The  fourth  pair  of  epimera 
are  so  large  as  to  include  within  the  posterior  margin  the  gland 
pore  usually  found  outside.  The  articulation  of  the  fourth  pair 
of  legs  also  lies  well  back  from  the  lateral  margin.  The  lateral 
expansion  sometimes  draws  so  far  forward  as  to  come  close  up  to 
the  second  epimera.  Just  behind  the  third  pair  of  legs,  the 
expansion  of  the  epimera  encloses  a  large  gland  pore.  The  posterior 
inner  edge  of  the  fourth  pair  is  nearly  straight,  making  the 
corner  almost  right-angled.     At  each  corner  a  short  hair  will  be 


THE    GENUS    LEBERTIA.  511 

observed.  The  anterior  ends  of  the  first  and  second  pairs  of 
epimera  have  each  a  moderately  long  hair.  There  are  two  or 
three  short  hairs  behind  the  first  segment  of  the  third  and 
fourth  pairs  of  legs.  The  posterior  extremities  of  the  first  pair 
of  epimera  end  in  a  point  about  midway  between  the  capitulum 
and  the  genital  area.  The  second  pair  also  ends  in  a  point,  but 
this  is  just  at  the  genital  area,  where  it  is  fused  with  the 
extremities  of  the  third  pair.  The  fourth  pair  is  rather  more 
rectangular,  as  the  inner  end  is  not  broader  than  the  outer.  The 
epimera  appear  to  be  more  fused  together  in  the  inner  area. 
The  sutures  are  broad,  but  not  well  defined. 

The  legs,  which  are  devoid  of  swimming  hairs,  do  not  appear  to 
possess  any  outstanding  features  of  much  moment.  The  distal 
end  of  the  sixth  segment  is  little,  if  any,  stouter  than  the  proximal 
end.  The  fourth  pair  of  legs  lies  close  up  to  the  suture  between 
the  third  and  fourth  pairs  of  epimera.  The  first  segment  has 
six  spines  on  its  extensor  surface.  The  fifth  segment  has  eight 
to  eleven  spines  and  the  sixth  segment  five  or  six  spines  on  the 
flexor  surface.     The  claws  are  of  normal  form  and  size. 

The  genital  area  is  small.  In  the  female  it  extends  very  little 
beyond  the  epimera,  and  in  the  male  not  at  all.  The  strong 
anterior  sclerite  is  roughly  triangular  in  shape.  The  posterior 
one  is  slender  and  arc  shaped.  The  acetabula  do  not  call  for 
special  comment.  The  posterior  one  is  almost  round  and  much 
smaller  than  the  two  anterior  elongated  ones.  The  valves  have 
six  to  nine  large  pores  along  their  outer  edge,  and  along  the  inner 
edge  there  are  a  number  of  fine  hair  pores,  ranging  in  the  case  of 
the  female  from  twelve  to  fifteen  and  in  the  case  of  the  male  from 
nineteen  to  twenty-four. 

The  anus  is  surrounded  by  a  strong  outer  chitinous  ring. 

Nymph. 

So  far  the  nymph  has  not  been  found  among  collections  outside 
of  Norway.  The  length  appears  to  range  from  0'50  to  0*63  mm., 
and  the  breadth  0*45  to  0*55  mm.  The  colour  of  the  oval-shaped 
body  is  about  that  of  the  imago,  while  the  skin  is  covered  with 
fine  chitinous  parallel  ridges. 

The  palpi  are  thick  and  about  0*22  mm.  in  length.  The  first 
segment  has  no  bristles.  The  second  has  three  on  its  extensor 
surface,  of  which  one  is  distal.     The  third  segment  has  three  long 


512      W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA  : 

bristles  on  its  inner  side,  one  of  these  being  nearly  proximal  and 
the  other  two  almost  distal,  one  of  them  being  on  the  extensor 
surface  and  the  other  just  inside  of  it.  The  fourth  segment  has 
three  fine  hairs  distal  on  the  extensor  surface,  and  two  fine  pores 
close  together  on  the  flexor  surface  as  in  the  imago. 

The  epimera  are  relatively  short  and  broad.  The  area  between 
the  fourth  pair  of  epimera  is  relatively  wider  than  in  the  imago, 
but  the  fourth  pair  itself  is  much  narrower,  so  that  the 
gland  pores  lie  well  outside.  The  inner  ends  of  the  second  pair 
are  much  broader,  while  the  inner  ends  of  the  fourth  pair  are 
cut  away  very  obliquely.  The  provisional  genital  area  lies  about 
half-way  beyond  the  epimera.  The  outer  ring  is  rather  more 
oval  than  round  and  has  only  four  minute  pores.  The  sclerite 
between  the  genital  area  and  epimera  lies  close  up  to  the  epimera. 
The  anal  ring  is  broad  but  not  strong. 

The  legs  have  no  swimming  hairs,  though  a  single  long  hair  at 
the  distal  end  of  the  fifth  segment  of  the  fourth  pair  of  legs  may  be 
observed.  The  first  segment  of  the  fourth  pair  of  legs  differs  from 
the  corresponding  segment  in  the  nymphs  of  other  sub-genera  in 
the  possession  of  three  bristles  on  the  extensor  surface. 

Lebertia  trisetica  Sig  Thor. 
(Sub-gen.   Hexalebertia.) 

1907.  Lebertia  trisetica  Sig  Thor.    Zool.  Anz.,  xxxii.  157,  fig.  91. 

This  form  is  allied  to  L.  stigmatifera,  but  in  comparison  with 
it  trisetica  will  be  found  to  possess  a  thicker  skin,  the  ridges  on 
which  are  stronger  and  broader,  with  a  greater  tendency  to 
branching.  The  intervals  between  the  ridges  are  broader  and 
minutely  porose.  So  far  as  can  be  judged  from  preserved 
material,  the  colour  would  appear  to  be  a  reddish  brown  with  a 
tinge  of  yellow. 

In  outline  the  body  is  oval  or  elliptical,  with  a  length  of  about 
0*9  mm.  and  a  breadth  of  about  0*7  mm.  Between  the  antenni- 
form  bristles  the  anterior  margin  is  weakly  concave. 

The  capitulum  is  about  0*21  mm.  in  length,  with  the  lateral 
processes  of  moderate  length  and  pointing  in  an  antero-lateral 
direction. 

The  palpi  are  relatively  slender,  and  are  a  little  over  0*4  mm. 
in  length,  the  individual   segments  being  about   0*035,    0*102, 


THE    GENUS    LEBERTIA.  513 

0-110,  0*143  and  the  terminal  segment  0034  mm.  It  will  be 
observed  that  the  third  segment  is  a  little  longer  than  the 
second.  The  second  and  third  segments  are  minutely  porose, 
but  the  fourth  is  not.  The  distribution  of  bristles  agrees  fairly 
well  with  that  of  the  allied  species,  but  it  is  to  be  noted  that 
those  on  the  extensor  surface  of  the  first  and  second  segments 
are  stronger,  while  the  bristle  on  the  flexor  surface  of  the 
second  segment  is  very  long  and  fine,  and  is  curved  upward. 
The  striking  characteristic  of  this  species  is  to  be  noted  slightly 
in  advance  of  the  middle  of  the  flexor  surface  of  the  fourth 
segment  in  the  shape  of  three  fine  pores  with  minute  setae, 
whence  the  specific  name  of  trisetica. 

The  epimera  are  strongly  developed  with  thick  sutures,  and 
the  inner  posterior  corners  of  the  fourth  pair  almost  rectangular. 
The  genital  area  is  about  0*22  mm.  in  length,  with  about  one- 
fourth  projecting  posteriorly  beyond  the  epimera.  The  inner 
edges  of  the  valves  have  about  twenty  fine  hairs  distributed 
along  their  length.  The  acetabula  are  long,  particularly  the 
two  anterior  pairs. 

The  anus  lies  near  the  posterior  body  margin,  and  is  sur- 
rounded by  a  stout  ring.  The  gland  pores  on  each  side  stand  out 
conspicuously,  as  well  as  those  at  the  posterior  inner  corner  of 
the  fourth  pair  of  epimera. 

The  species  was  described  from  material  taken  in  Surrey 
in  1896,  and  so  far  it  has  not  been  recorded  from  anywhere  else. 

DESCRIPTION   OF   PLATES. 

Plate  33. 

Fig.  1.  L.  porosa.  Dorsal  surface,   x  22. 

„     2.  L.  porosa.  Epimera  of  adult,  x  66. 

„     3.  L.  porosa.  Epimera  of  nymph,  x  66. 

„     4.  L.  porosa.  Larva,  ventral  surface,  x  94. 

Plate  34. 

Fig.    1.  L.  tau-insignita.      Ventral   surface,    x  26.      (After  Sig 
Thor.) 

2.  L.  tau-insignita.     Genital  area,  x  80.     (After  Sig  Thor.) 

3.  L.  tau-insignita.     Inner  side  of  left  palp,  x  133.     (After 
Sig  Thor.) 


5> 


514     W.    WILLIAMSON    AND    C.    D.    SOAR    ON    BRITISH    HYDRACARINA. 

Fig.    4.  L.fimbriata.     Inner  side  of  left  palp,  x  133.     (After  Sig 

Thor.) 
„      5.  L.fimbriata.     Fourth  leg,   x  60. 
„      6.  L.  trisetica.     Dorsal  surface,   x  39. 
,,      7.  L.  trisetica.     Fourth  leg,   x  00. 
,,      8.  L.  trisetica.     Inner  side  of  left  palp,  x  147.     (After  Sig 

Thor.) 
„      9.  L.  trisetica.     Skin  markings. 
,,    10.  L.  stigmatifera.     Inner  side  of  left  palp,  x  147.     (After 

Sig  Thor.) 
„    11.  L.  stigmatifera.     Genital  area,   x$Q. 
„    12.  L.  glabra.     Inner  edge  of  right  palp,  x  147.     (After  Sig 

Thor.) 
,,    1 3.  L.  glabra.     Fourth  leg,   x  60. 
„    14.  L.  porosa.     Fourth  leg,  x  60. 
,,    15.  L.  porosa.     Inner  edge  of  right  palp,  x  117.     (After  Sig 

Thor.) 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  76,  April  1915. 


Jourx.  Q.M.C. 


Ser.  2.  Vol.  XIL.  PL  33. 


• 


*=*=*, 


i       ft    :; 


C.  D.  Soar,  del  ad  nat. 


The  Genus  Lebertia. 


Journ.  Q.M.C. 


Sri'.  2,  Vol.  XII.,  PL  34. 


C.  D.  Soar,  del. 


T 


The  Genus  Lebertia. 


515 


A    "NEW"    OBJECT   GLASS    BY   ZEISS. 

By  J.  W.  Gordon. 

{Read  March  23rd,  1915.) 
Figures  1  and  2. 

In  the  November  number  of  the  Journal  of  the  Club  there 
is  a  paper  by  Mr.  Nelson  upon  a  new  object  glass  by  Zeiss. 
Of  this  object  glass  Mr.  Nelson  speaks  in  high  praise,  and  no 
doubt  it  merits  the  encomium  which  he  bestows  upon  it.  Besides 
describing  its  performance,  Mr.  Nelson  attributes  entire  novelty 
to  the  plan  upon  which  this  objective  is  constructed.  That  plan 
is  the  fitting  of  an  oil -immersion  front  lens  to  a  |-in.  dry 
objective  so  that  an  oil-immersion  objective  is  produced  having 
a  numerical  aperture  less  than  1.  Mr.  Nelson  certifies  that,  so 
far  as  his  knowledge  goes,  this  type  of  objective  is  quite  new. 

From  the  merit  of  Messrs.  Zeiss  in  recognising  the  advantage 
to  be  secured  by  applying  the  oil -immersion  front  lens  in  this 
way,  I  do  not  at  all  wish  to  detract ;  but  it  is  perhaps  worth 
while  to  point  out  that  the  idea  is  not  quite  so  new  as  Mr.  Nelson 
supposes.  So  far  back  as  July  1909,  Messrs.  It.  &,  J.  Beck 
produced  and  supplied  to  me  a  lens  which  was  precisely  of  this 
type,  and  in  design  identical  with  this  new  lens  of  Zeiss,  although 
in  fact  the  oil-immersion  front  lens  was  applied  to  a  g-in.  dry 
objective.  This  lens  I  have  had  in  constant  use  since  then,  and 
have  exhibited  it  on  various  occasions.  I  am  a  little  surprised 
to  learn  from  Mr.  Nelson's  paper  that  I  have  not  actually  shown 
it  to  him.  It  was  catalogued  for  exhibition  at  South  Kensington 
at  the  time  of  the  Optical  Convention,  and  although  there  was  a 
difficulty  about  the  space,  so  that  the  lens  itself  was  not  actually 
set  up  there,  the  following  description  of  it  appears  in  the 
catalogue  : 

"  The  use  of  oil  immersion  has  hitherto  been  confined  to 
objectives  of  the  l/8th-in.  and  l/12th-in.  class  under  an  im- 
pression, which  proves  to  be  mistaken,  that  oil  immersion  secures 
no  particular  advantages  when  applied  to  objectives  of  lower 
power.  The  model  is  a  |-in.  dry  lens  fitted  with  a  supplementary 
lens  of  rather  less  than  hemispherical  angle,  mounted  so  that  the 


516         J.    W.    GORDON    ON    A    "NEW        OBJECT    GLASS    BY    ZEISS. 

centre  of  the  sphere  lies  in  the  object.  The  spherical  surface, 
therefore,  produces  no  refraction,  and  its  addition  to  the  optical 
system  involves  no  change  in  the  correction  of  an  objective 
adjusted  for  viewing  an  uncovered  object.  The  abolition  of  the 
top  surface  of  the  cover  glass  by  oiling  on  the  supplementary 
front  lens  produces  an  increase  of  50  per  cent,  in  magnifying 
power,  and  a  commensurate  increase  in  light-gathering  power. 
The  catoptric  haze  produced  by  internal  reflection  from  the  front 
face  of  the  permanent  front  lens  sinks  into  comparative  in- 
significance, and  a  g-in.  dry  lens  is  converted  into  a  3 -in. 
immersion  system  of  much  improved  defining  power." 
Two  things  may  be  added  to  this  description  : 

(1)  The  numerical  aperture  of  this  lens  as  it  stands  is  0*54. 

(2)  It  was  intended  that  this  front  lens  should  be  made 
adaptable  not  only  to  the  g-in.  mentioned,  but  also  to  my  |-in. 
objective,  in  which  case  it  would  have  yielded  exactly  the 
combination  which  Mr.  Nelson  now  describes.  It  was  found, 
however,  that  the  front  lens  was  a  little  too  thick  for  use  with 
a  I  -in.  objective,  and  consequently  I  have  never  been  able  to 
adapt  it  to  a  higher  power  than  the  g-in.  The  principle,  how- 
ever, upon  which  the  construction  is  based  is  clearly  set  out 
in  the  extract  above  given  from  the  catalogue  of  the  Optical 
Convention,  and  if  Messrs.  Zeiss  have  given  any  attention  to 
that  document,  it  is  obvious  that  for  upwards  of  a  twelve-month 
past  they  have  had  the  benefit  of  the  suggestion  so  made  public. 
It  is,  of  course,  quite  possible  that  the  Jena  House  have  paid  no 
attention  to  the  catalogue  of  the  Optical  Convention,  but  have 
worked  out  the  theory  of  this  new  objective  for  themselves. 
Even  if  we  suppose  that  they  have  profited  by  the  publication 
which  has  been  placed  at  their  service,  we  must  still  concede 
to  them  the  merit  of  being  the  first  to  turn  to  account  a  sug- 
gestion which  has  been  equally  at  the  disposal  of  our  own 
British  manufacturers. 

While  I  am  on  this  point  I  should  like  to  communicate  to 
the  members  of  the  Club  a  further  development  of  this  principle. 
In  consequence  of  the  failure  of  this  lens,  as  I  have  explained, 
to  serve  the  purpose  as  an  oil-immersion  front  lens  for  my  |-in. 
objective,  I  was  led  to  provide  myself  with  another,  of  which 
a  sketch  appears  as  fig.  1.  It  is  adapted,  as  will  be  seen,  to 
be  mounted,   not   on  the  dry  objective,   but  on  the  cover  glass 


J.    W.    GORDON    ON    A    "  NEW "    OBJECT    GLASS    BY    ZEISS.        517 

of  the  specimen.  A  shallow  brass  ring  enables  the  observer 
to  move  it  about,  and  place  it  wherever  he  pleases  on  the 
specimen,  so  that  it  exactly  covers  the  spot  which  he  desires 
to  examine.  If,  then,  he  places  this  specimen  with  this  sup- 
plemental lens  in  position  under  his  dry  objective,  he  gets, 
in  effect,  precisely  the  combination  which  Mr.  Nelson  describes. 
It  is  to  be  observed  that  in  this  combination  it  is  not  necessary 
to  make  any  corrections  for  colour  or  for  spherical  aberration, 
because  if  the  lens  is  of  the  right  thickness,  so  that  the  centre 
of  its  spherical  surface  coincides  with  the  focal  point,  then  the 
incident  beam  passes  the  air-glass  surface  of  the  lens  without 
refraction.  It  passes,  therefore,  without  aberration  of  any  kind, 
and  the  dry  lens  is  in  exactly  the  same  position  as  if  it  were 
applied  to  a  dry  object.  In  the  case  of  a  dry  lens  which  is 
corrected   for   the  cover  glass   this  would,  of    course,   be    a    dis- 


z 


COVER  CLASS. 


BRASS  RING. 


-LENS.     "--GLASS  BASE. 

Fig.  1. 


advantage,  but  a  dry  lens  which  is  adapted  to  be  used  upon 
a  dry  object  will  give,  under  these  conditions,  a  perfect  image. 
That  is,  no  doubt,  the  principle  of  construction  of  the  Zeiss  lens 
which  Mr.  Nelson  describes. 

To  complete  the  description  of  this  new  adjunct :  The  brass 
ring  is  mounted  upon  a  thin  cover  glass  which,  in  its  turn, 
carries  the  spherical  lens  cemented  at  its  centre.  Theoretically, 
of  course,  the  lens  and  cover  glass  should  be  of  the  same  glass, 
but  in  the  case  of  my  model  I  have  used  what  I  had  ready  to 
hand,  without  being  punctilious  upon  this  point. 

Such  a  supplemental  lens  is  for  some  purposes  a  very  con- 
venient adjunct  to  the  ordinary  microscope.  In  the  first  place, 
it  puts  the  microscopist  in  possession  of  a  system  such  as  Mr. 
Nelson  has  described,  at  extremely  small  cost,  for,  of  course,  this 
appliance,  consisting  simply  of  a  small  brass  ring,  a  cover  glass, 
and  an  uncorrected  spherical  lens  cemented  together,  can  be 
produced  at  almost  infinitesimal  cost.     It  is    then  available  for 


518 


J.  W.  GORDON  ON  A  "  NEW  "  OBJECT  GLASS  BY  ZEISS. 


use  with  any  dry  lens  as  required,  of  which  it  will  increase  the 
magnifying  power  by  50  per  cent,  with  a  proportionate  increase 
in  the  amount  of  light  collected,  so  that  the  enlarged  image  loses 
nothing  in  brightness.  In  this  sense  it  increases  the  resolving 
power  of  the  system,  inasmuch  as  it  increases  the  scale  upon 
which  all  the  details  are  shown. 

That,  however,  is  but  the  least  part  of  its  merit.  If  that  were 
all  it  would  only  constitute  a  |-in.  objective  the  equivalent  of 
^  in. ;  I  in.  the  equivalent  of  i  in.,  and  so  on.  What  is  very 
much  more  important  is  that  it  gets  rid  of  the  top  light  reflected 
down  upon  the  surface  of  the  object  by  the  upper  surface  of  the 
cover  glass.  It  does  not  seem  to  be  at  all  generally  understood 
by  microscopists  how  much  resolving  power  is  lost  by  reason  of 
the  fog  produced   by  these  reflections  from  the  upper  surface  of 


COVER  GLASS. 


Fig.  2. 


the  cover  glass.  When  we  are  examining  an  object  like  a 
diatom  by  transmitted  light  and  producing,  by  means  of  that 
transmitted  light,  what  the  late  Prof.  Abbe  used  to  call  an 
absorption  image — that  is  to  say,  an  image  in  which  the  face 
presented  to  us  by  the  object  is  seen  in  shadow — it  is  of  first-rate 
importance  that  the  shadows  should  not  be  illuminated  by  top 
light.  A  dry  cover  glass  sends  back  upon  the  upper  surface  of 
the  object  a  large  amount  of  such  top  light,  thereby  obscuring  the 
contrast  by  virtue  of  which  the  image  is  seen.  Furthermore,  if 
the  object  is  not  in  actual  optical  contact  with  the  glass,  there 
is  sure  to  be  a  reflecting  surface  between  the  glass  and  the 
mounting  medium  which  is  illuminated  by  this  top  light  and 
again  produces  a  brilliant  haze  through  which  the  object  has  to 
be  viewed.  The  diagram  fig.  2  will  serve  to  illustrate  these 
points.      Here  a  section  is  taken  through  the  cover  glass  with 


J.    W.    GORDON    ON    A    "  NEW  "    OBJECT   GLASS    BY    ZEISS.        519 

its  upper  surface  dry  and  through  the  mounting  medium  and 
the  specimen.  The  specimen  is  represented  by  two  opaque 
objects,  one  in  optical  contact  with  the  under  surface  of  the 
cover  glass,  the  other  at  some  little  distance  below  the  surface, 
so  that  there  is  no  optical  contact  in  the  second  case.  A  line 
marked  R  indicates  how  light  from  the  condenser  is  reflected 
downward  from  the  upper  surface  of  the  cover  glass,  and  then 
upward  from  its  lower  surface  so  as  to  produce  a  luminous  haze 
overspreading  the  field  except  where  optical  contact  between  the 
specimen  and  the  cover  glass  does  away  with  the  second  reflection. 
It  will  be  seen  that  the  shadows  produced  by  transmitted  light 
are  attenuated  by  this  reflected  light  wherever  the  object  does 
not  come  into  optical  contact  with  the  cover  glass.  Similar 
considerations  show  that  the  light  which  is  internally  reflected 
from  the  upper  surface  of  the  front  lens  and  again  internally 
reflected  from  the  lower  surface  of  that  front  lens  gives  rise  to 
a  similar  catoptric  haze  which  is  diffused  over  the  whole  field  and 
serves  therefore  to  attenuate  the  absorption  image  even  of  these 
objects  which  are  in  optical  contact  with  the  cover  glass. 

Now  all  this  mischief,  so  far  as  it  is  due  to  internal  reflections 
in  the  cover  glass,  is  avoided  by  the  use  of  a  spherical  lens 
cemented  on  to  the  cover  glass,  since  by  its  means  all  such 
internal  reflection  is  abolished.  From  this  cause  chiefly  results 
the  improved  definition  which  gives  to  these  immersion  objectives 
of  low  angle  their  comparatively  high  resolving  power. 

Besides  its  extreme  cheapness,  this  new  form  of  immersion 
lens  has  the  merit  of  serving  as  a  finder.  For  example,  an 
observer  who  wishes  to  keep  a  particular  object — say  a  culture — 
under  observation  for  a  length  of  time  can  cement  one  of  these 
supplementary  lenses  in  place  over  the  spot  occupied  by  his 
specimen  and  put  the  specimen  away  in  that  condition.  When 
next  he  goes  to  examine  it  he  will  find  it  without  the  least 
difficulty,  for  all  that  he  has  to  do  is  to  place  his  slide  on  the 
stage  of  his  instrument  with  this  cemented  lens  in  the  axis  of 
collimation.  It  is  possible,  now  that  Messrs.  Zeiss  have  dis- 
covered and  advertised  the  value  of  low-power  immersion  objec- 
tives, that  this  very  simple  appliance  may  also  find  a  manufacturer. 
Hitherto,  I  have  not  succeeded  in  interesting  any  of  our 
manufacturers  in  it,  possibly  because  the  market  price  would 
necessarily  be  small.      As  against  that  consideration,   however, 


520        J.    W.    GORDON    ON    A    "  NEW  "    OBJECT    GLASS    BY    ZEISS. 

it  may  be  pointed  out  that  bacteriologists  would  probably  find  it 
worth  their  while  to  buy  this  piece  of  apparatus  in  considerable 
quantities,  if  it  were  to  be  had  at  a  reasonable  price,  since  it 
would  very  considerably  facilitate  their  labour  where  a  series 
of  observations  have  to  be  made  upon  one  given  specimen  of 
culture. 


Journ.  Qutkett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  76,  April  1915. 


521 


MICROSCOPICAL  METHODS  IN   BRYOLOGICAL  WORK. 

By  G.  T.  Harris. 

{Read  March  23rd,  1915.) 

If  any  apology  is  needed  for  bringing  before  the  Quekett 
Microscopical  Club  a  subject  that  may  only  be  of  interest  to  a 
limited  number  of  its  members,  I  would  find  it  in  the  fact  that 
some  years  ago  the  Club  had  in  Dr.  Braithwaite  a  president 
whose  supreme  interest  was  bryological  work.  As  long  as 
bryology  interests  and  attracts  scientific  workers  will  Dr.  Braith- 
waite's  name  be  held  in  honour,  and  his  magnificent  British 
Moss  Flora  rank  with  the  splendid  natural  history  monographs 
published  during  the  nineteenth  century. 

It  is  easy  to  understand  that  mosses  do  not  appeal  very 
strongly  to  the  microscopist  per  se,  as  the  work  to  be  done 
amongst  them  is  more  or  less  systematic ;  they  offer  no 
problems  of  resolution  (that  I  know  of),  their  development  is 
quite  well  understood,  and  even  an  infatuated  bryologist  would 
be  reluctant  to  advise  an  excursion  amongst  them  in  search  of 
"display"  objects.  In  spite  of  these  drawbacks,  however,  it 
would  be  difficult  to  find  a  class  better  adapted  to  the  require- 
ments of  the  microscopist  desirous  of  confining  himself  to  some 
special  group,  and  more  especially  to  microscopists  resident  in 
large  cities.  Mosses  may  be  gathered  when  opportunity  permits, 
dried  and  stored  for  months,  indeed  years,  and  yet  resume  their 
original  appearance  when  moistened  previous  to  examination. 
Sufficient  material  for  a  whole  winter's  work  can  easily  be 
collected  during  the  annual  vacation,  and  it  is  unnecessary  to  go 
to  any  particular  district,  unless  of  course  special  forms  are 
required.  Even  an  orchard  is  favourable  ground,  especially 
when  the  trees  reach  that  desirable  standard  "  old  and  crusted." 
Winter  is  par  excellence  the  moss  season,  they  then  practically  take 
over  the  country-side.  There  is  no  overgrowth  of  phanerogamous 
plants  to  conceal  their  presence ;  the  hepatics  may  in  some 
districts  set  up  a  rival  claim  for  notice,  but  as  many  bryologists 
are  also  hepaticists  this  is  not  a  disadvantage  when  collecting. 

Journ.  Q.  M.  C,  Series  II.— No.  76.  36 


522  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

They  are  not  in  the  least  particular  where  they  grow,  any 
ineligible  site  will  do  for  them.  The  only  disturbing  factor  in 
the  life  of  a  moss  that  I  am  acquainted  with  is  an  east  wind. 
They  will  stand  all  the  indignities  that  man  in  the  shape  of  an 
agricultural  labourer  can  inflict  upon  them,  but  with  an  east 
wind  they  make  no  manner  of  compromise,  they  shrivel  up ;  and 
how  tightly  a  moss  can  screw  itself  up  must  be  seen  to  be 
believed.  Nothing  more  unlike  the  beautiful  silky,  pinnate 
stems  of  Hypnum  sericeum  can  be  imagined  than  the  same  stems 
showing  their  disgust  with  an  east  wind.  It  is  obvious  that  moss 
collecting  in  an  east  wind  is  more  or  less  of  a  failure. 

The  earlier  bryologists  relied  mainly  upon  herbarium  sheets 
for  the  preservation  of  their  specimens,  and,  while  admitting  that 
the  herbarium  is  an  essential  in  systematic  work,  I  incline  to  the 
opinion  that  insufficient  attention  has  been  paid  to  the  formation 
of  what  may  be  described  as  the  micro-herbarium.  Herbarium 
sheets  at  the  best  can  give  only  the  general  habit  of  the  plant, 
and,  indeed,  in  a  very  large  number  of  species  even  this  is  so 
poorly  preserved  as  to  be  practically  valueless.  The  specific 
differences  are  dependent  upon  microscopic  structure,  and  either 
mounted  slides  or  fresh  material  must  be  referred  to  before  the 
species  can  be  named  with  certainty.  Thirty  years  ago  specific 
distinctions  were  largely  dependent  upon  general  habit  and  such 
simple  low-power  observations  as  the  presence  or  absence  of  the 
so-called  "  nerve,"  its  length,  and  the  nature  of  the  leaf  margin. 
Hence  we  find  Berkeley  contenting  himself  with  the  brief  remark 
that  an  objective  of  one-third  of  an  inch  is  the  most  convenient 
for  examining  the  leaves,  while  low  powers  are  sufficient  for  the 
determination  of  genera  and  species.  Since  then  bryology  has 
become  more  and  more  a  microscopical  study,  and  Berkeley  would 
probably  have  been  aghast  had  he  been  told  that  almost  in  his 
own  day  specific  determination  would  be  to  a  considerable  extent 
a  matter  of  cell-measurement.  Even  Braithwaite  kept  outside 
the  region  of  the  micron.  It  can  be  seen  that  the  modern 
bryologist  has  of  necessity  to  be  at  least  a  fairly  competent 
microscopist,  and  that  the  time  has  come  when  the  carefully 
displayed  sheets  of  the  moss  herbarium  mean  very  little  to  the 
critical  systematist.  No  bryologist  in  the  present  day  would  care 
to  decide  upon  the  specific  names  of  a  large  number  of  our 
British  mosses  from  an  examination  in  the  field,  even  with  the 


IN    BRYOLOGICAL    WORK.  523 

aid  of  a  good  lens.  The  inevitable  result  is  that  the  micro- 
herbarium  becomes  increasingly  more  important  to  the  systematic 
bryologist. 

The  collection  of  slides  the  Quekett  Microscopical  Club  has 
done  me  the  honour  of  accepting  is  fairly  representative  of  the 
kind  of  slide  useful  to  the  bryologist,  although  I  have,  in  the  hope 
of  proselytising  amongst  the  members,  made  it  more  popular  than 
would  otherwise  have  been  the  case.  There  is  no  question  of 
making  attractive  mounts  with  the  bryologist,  even  if  mosses  lent 
themselves  to  such  a  proceeding.  By  the  time  the  modern 
student  of  mosses  has  decided  whether  some  moss  is  a  sub-species, 
variety,  form,  or  hybrid  of  a  certain  species,  he  is  usually  beyond 
the  ambition  of  making  an  attractive  mount  of  it,  and  merely 
desires  to  see  it  safely  under  a  cover-glass  for  future  reference. 
From  the  student's  point  of  view  the  collection  would  undoubtedly 
have  been  of  far  greater  usefulness  had  it  consisted  of  series 
showing  varietal  differences  in  such  difficult  forms  as  exist 
amongst  the  Harpidioid  Hypna,  but  the  general  interest  of  such 
a  collection  would  have  been  nil.  The  casual  excursionist  into 
the  moss  world  is  more  concerned  with  general  impressions  than 
varietal  distinctions,  and  the  microscopist  who  values  his  whole- 
some outlook  on  Nature  will  leave  such  sections  as  the  Harpidioid 
Hypna  to  its  creators. 

To  the  confirmed  microscopist  I  fear  the  class  Musci  can  never 
be  very  attractive,  as  it  is  difficult,  except  in  a  limited  degree,  to 
obtain  clean,  immaculate  slides.  The  cleaning  of  such  species  as 
Fissidens  exilis,  Pottia  minutula,  etc.,  which  not  only  live  on 
tenacious  clay  formations,  but  succeed  in  covering  themselves 
entirely  with  it,  is  appalling  if  conscientiously  carried  out,  and 
usually  quite  fruitless,  as  by  the  time  the  clay  has  been  removed 
the  specimen  is  in  fragments  and  not  worth  mounting.  Hence 
cleanliness  is  next  to  uselessness  in  bryological  work,  and  a  really 
useful  collection  of  moss  slides  occupies  a  debatable  position 
between  the  geological  and  botanical  kingdom i.  I  mention  this 
in  case  your  Hon.  Curator  is  puzzled  as  to  which  kingdom  some 
of  the  slides  are  intended  to  represent.  A  coi  siderable  amount 
of  soil  usually  adhering  to  the  specimens  may  be  got  rid  of  by 
prolonged  soaking,  repeatedly  changing  the  water,  and  very 
considerable  help  is  got  by  strongly  acidulatiag  the  water  with 
hydrochloric    acid ;    especially    is    this    the    case    in    calcareous 


524  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

districts.  Boiling  the  specimen  may  help  matters  if  it  is  thought 
the  moss  is  robust  enough  to  stand  the  treatment,  and  some 
species  certainly  will.  But  the  application  of  a  stiff  camel-hair 
pencil  is  always  necessary  to  dislodge  the  particles  that  adhere 
in  spite  of  all  soaking  and  boiling.  And  when  all  has  been  done 
there  is  always  the  victorious  residuum  to  jibe  at  one's  efforts. 
Many  species  are  so  fragile  that  any  attempt  at  cleaning  beyond 
the  most  superficial  seriously  injures  the  specimen  ;  such  is  the 
case  with  those  species  having  highly  papillose  leaves — in  fact 
such  leaves  are  rarely  found  perfect,  so  easily  do  the  papillose 
cells  break  away  from  each  other.  It  is  obvious  that  the 
question  of  cleaning  the  material  is  a  serious  tax  on  the  time  of 
the  bryologist,  and  that  there  really  is  a  valid  excuse  for  his 
mounts  not  being  the  immaculate  objects  usually  achieved  by 
the  microscopist. 

Another  cause  contributing  to  indifference  in  bryologists' 
slides  is  the  necessity  that  exists  for  accomplishing  a  considerable 
amount  of  work  in  a  short  time.  The  busy  systematist  spends  so 
much  time  in  the  examination  and  naming  of  his  specimens  that 
the  margin  of  time  available  for  the  preparation  and  mounting 
of  slides  to  illustrate  his  species  is  too  meagre  to  allow  of 
deliberate  and  painstaking  care,  hence  a  slide  which*  would  be 
better  for  remounting  is  allowed  to  pass  if  it  shows  clearly  the 
desirable  features.  It  is  without  doubt  the  need  for  the  minimum 
of  trouble  in  mounting  that  has  caused  the  majority  of  bryo- 
logists to  rely  on  glycerine  jelly  for  obtaining  their  mounts.  At 
least  I  have  ascertained  that  many  quite  eminent  workers  do 
rely  on  this  medium,  and  from  what  I  have  heard  I  fear  to  their 
undoing.  Some  years  ago,  by  great  industry,  I  amassed  a 
considerable  collection  of  slides  illustrating  the  Hypnaceae, 
spending  the  leisure  hours  of  an  entire  winter  in  doing  so,  and 
in  twelve  months'  time  I  had  the  pleasant  experience  of  washing 
them  off,  as  slides  so  illustrative  of  lacunae  and  every  phase  of 
cavity  were  of  no  use  to  me.  As  I  had  slides  mounted  in 
glycerine  jelly  perfectly  good  after  a  lapse  of  six  years,  it  was 
obvious  that  it  was  not  necessarily  an  unreliable  medium,  and  as 
I  believe  it  to  be  the  most  convenient  medium  for  general  work 
in  bryology  I  give  the  following  hints  to  novices  for  what  they 
may  be  worth.  In  the  first  place,  the  jelly  itself  must  not  be 
made  with  a  hard  gelatine.     I  used  Drescher's  emulsion  gelatine, 


IN    BRYOLOGICAL    WORK.  525 

which  is  an  extremely  clear  but  hard  gelatine,  and  this  was  the 
principle  cause  of  my  disaster.  The  jelly  must  contain  a  good 
proportion  of  glycerine.  Kaiser's  formula  appears  to  be  a  very 
good  one  if  home  preparation  is  in  view,  as  it  does  not  set  hard. 
I  have  slides  six  years  old  mounted  with  it  which  have  suffered 
no  deterioration.  The  object  to  be  mounted  should  be  soaked  for 
a  considerable  time  in  equal  parts  of  glycerine  and  water  (in  my 
own  work  they  always  have  twenty-four  hours)  ;  unless  the 
structure  of  the  object  is  thoroughly  permeated  with  the  dilute 
glycerine,  lacunae  are  sure  to  develop  by  subsequent  absorption. 
My  own  experience  leads  me  to  the  conclusion  that  a  point  of 
great  importance  in  using  glycerine  jelly  so  as  to  ensure  reliable 
mounts,  is  to  avoid  mounting  the  object  with  the  jelly  at  a  high 
temperature;  it  should  be  used  at  just  about  the  melting-point. 
If  the  temperature  is  high,  subsequent  contraction  is  considerable 
and  cavities  around  the  object  are  not  unlikely  to  make  an 
appearance  later  on. 

Another  point  where  many  mounters  err,  especially  bryolo- 
gists,  is  in  applying  considerable  pressure  to  the  cover-glass 
until  the  jelly  has  set,  thus  pressing  out  the  bulk  of  the  jelly  and 
leaving  only  a  thin  film  between  the  slip  and  cover-glass.  It  is 
very  nice  to  have  a  leaf  mounted  perfectly  flat  so  that  the  cells 
can  be  studied  from  apex  to  base  without  focusing  down  through 
the  convexity  of  the  leaf ;  but  such  slides  are  seldom  permanent. 
The  amount  of  jelly  should  be  sufficient  to  cover  the  object ;  and 
it  is  easy,  when  constantly  using  jelly,  to  guess  just  about  the 
amount  that  will  cover  the  object  and  spread  to  the  edge  of  the 
cover-glass  when  it  is  placed  in  position.  When  the  jelly  has 
thoroughly  set,  if  any  has  escaped  beyond  the  edge  of  the  cover- 
glass  it  should  be  washed  away.  Personally,  I  lay  the  slide 
aside  for  about  twenty-four  hours  after  mounting,  then  give  it  a 
good  scrubbing  with  a  moderately  stiff  tooth  brush  under  a  jet  of 
water.  This  frees  it  from  all  glycerine  outside  the  cover.  The 
slide  is  then  ringed  with  a  plain  solution  of  good  hard  gelatine, 
the  strength  of  the  solution  being  immaterial  so  long  as  it  is  not 
a  weak  one.  When  this  has  set,  which  it  will  do  quite  quickly, 
it  is  brushed  over  with  a  10  per  cent,  solution  of  chrome  alum. 
At  firs-t  I  used  formalin,  but  found  that  its  indurating  action  was 
so  great  that  the  ring  of  gelatine  split  and  peeled  off.  Chrome 
alum  toughens  rather  than  hardens  the  gelatine.     In  its  present 


526  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

state  the  slide  is  perfectly  safe  for  months,  and  may  be  finished 
at  some  convenient  time  subsequently.  The  finishing  consists  in 
ringing  with  old  gold  size,  coat  after  coat,  with  intervals  to  allow 
for  hardening. 

I  have  been  most  desirous  of  making  glycerine  jelly  mounting 
a  reliable  process,  owing  to  its  great  usefulness  in  rapidly  mount- 
ing reference  slides  of  leaves  and  small  species  of  moss.  Unfortu- 
nately I  have  received  several  bad  shocks  in  my  own  work,  and 
in  reports  from  other  bryologists,  and  I  must  frankly  confess  to  a 
grave  misgiving  in  asking  the  Quekett  Microscopical  Club  to 
accept  slides  mounted  in  this  medium.  Only  the  fact  that  I 
believe  some  of  the  principal  pitfalls  to  have  been  traced  and 
overcome  has  permitted  me  to  include  any  at  all.  Certainly  for 
a  long  time  past  now  I  have  been  immune  from  my  former 
perennial  crop  of  lacunae  and  cavities.  In  all  cases  the  date  of 
preparation  has  been  marked  on  the  slides,  and  if  they  are  not  an 
example  at  least  they  will  be  a  warning. 

Unless  the  object  is  of  an  appreciable  thickness  the  film  of 
jelly  necessary  to  cover  it  will  not  be  so  thick  as  to  need  any 
support ;  but  if  some  species,  or  portions  of  large  species,  are 
mounted  with  their  capsules  the  amount  of  jelly  necessary  may 
need  some  support  at  the  edge  to  keep  the  cover-glass  even.  A 
convenient  way  of  doing  this  is  to  use  a  ring  of  silver  wire  about 
the  diameter  of  the  cover-glass  and  of  a  thickness  proportioned  to 
the  object.  Practically  a  thickness  of  23  B.W.G.  meets  all  needs, 
and  I  confine  myself  to  this  thickness.  Silvered  wire  is  easily 
and  quickly  prepared  by  taking  copper  wire  of  the  desired  thick- 
ness, thoroughly  cleaning  it  from  all  grease,  and  immersing  it  in 
silver  cyanide  solution.  It  can  then  be  kept  on  a  reel,  and  cut 
off  as  required.  The  ring  needs  no  attaching  to  the  slip,  as  the 
gelatine  holds  it  in  position ;  but  it  may  be  slightly  flattened  by 
hammering. 

Farrant's  medium  probably  comes  next  to  glycerine  jelly  in 
usefulness  to  the  bryologist ;  it  is  very  convenient  to  use,  and,  of 
course,  allows  of  great  deliberation  in  arranging  the  object,  re- 
moving such  undesirable  matter  as  can  be  removed,  and  it  gives 
good  transparency  to  incrassate  cells.  For  peristomes,  which 
require  to  be  examined  by  transmitted  light,  it  is  excellent, 
though  the  fragile  endostomes  of  some  species  are  made  too  trans- 
parent by  it. 


IN    BRYOLOGICAL    WORK.  527 

When  my  loss  of  the  twelve  dozen  type  slides  of  the  Hypnaceae 
shook  my  faith  in  glycerine  jelly  I  made  experiments  in  search  of 
a  substitute,  and  found  an  extremely  good  one  in  copper  acetate 
combined  with  glycerine.  The  formula  is  given  in  Squire's 
Methods  and  Formulae,  but  is  not  referred  to  any  author.  It 
has  the  advantage  of  being  also  a  fixing  agent : 


Copper  acetate 
Mercury  chloride 
Acetic  acid   . 
Glycerine 
Distilled  water 


02  gramme. 

0-4        „ 

0-2  c.c. 
25-0    „ 
25-0    „ 


This  gives  a  certain  amount  of  transparency  to  the  cellular 
structure  of  the  leaves,  but  it  naturally  imposes  much  more 
labour  on  the  mounter,  and  is  better  suited  to  the  microscopist 
who  merely  wants  mosses  for  general  interest. 

A  large  number  of  mosses  are  so  minute  that  they  are  quite 
useless  as  herbarium  specimens,  and  the  only  satisfactory  way  is 
to  possess  them  mounted  as  microscopical  slides ;  such  species  are 
Fissidens  exilis,  F.  pusillus,  F.  viridulus,  the  majority  of  the 
species  of  the  genera  Pottia,  Ephemerum,  Pleuridium,  etc. 
The  leaves  of  these  small  species  are  usually  very  transparent 
and  do  not  require  to  be  made  additionally  so  by  glycerine,  even 
when  dilute.  Acetate  of  potash  is  an  admirable  mountant  for 
such  forms,  especially  when  containing  a  trace  of  copper  acetate. 
The  following  formula  has  given  me  satisfaction,  it  is  based  on 
the  one  Prof.  G.  S.  West  recommended  for  algae : 

Copper  acetate O05  gramme. 

Potassium  acetate 10         ,, 

Water 25-0    c.c. 

Formalin,  2|  per  cent,  solution,  may  also  be  used  for  these 
minute,  transparent  species,  but  in  slides  that  have  been  mounted 
a  number  of  years  I  have  noticed  that  the  formol  sometimes 
precipitates,  so  that  I  have  been  reluctant  to  use  it  to  any  con- 
siderable extent.  On  the  other  hand,  many  slides  in  formol 
appear  to  have  kept  perfectly,  so  that  much  may  depend  on  the 
sample  of  formol  used. 

With  leaves  of  such  species  as  Andrea  Bothii,  which  are 
extremely  dark  in  colour  and  of  leathery  consistency,  it  is  im- 


528  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

possible  to  examine  the  structure  satisfactorily  in  its  normal 
condition,  and  they  are  best  treated  in  a  solution  of  caustic  soda 
or  potash,  as  recommended  by  Dr.  Braithwaite.  This  renders 
them  flaccid  and  defines  the  cell  structure.  They  should,  of 
course,  be  washed  well  before  mounting,  and  glycerine  in  some 
form  is  desirable  with  them  as  with  all  dense-leaved  species. 
The  species  of  Andreaea  are  typical  of  the  difficulties  that  con- 
front the  bryologist  in  attempting  to  get  satisfactory  permanent 
mounts.  They  are  deep  red  or  black-brown  in  colour,  very  dense 
and  cartilaginous  in  texture,  extremely  brittle  and  abominably 
dirty.  It  may  be  remarked  that  the  colour  of  moss  leaves, 
which  is  usually  some  shade  of  green,  is  a  matter  of  minor 
importance  to  the  mounter,  hence  it  can  be  left  out  of  considera- 
tion in  choosing  a  medium  for  mounting.  The  bryologist  mounts 
the  leaves  altogether  for  shape  and  cell-form,  as  upon  these 
depend  in  a  great  measure  the  determination  of  the  species. 
Usually  the  colour  disappears  in  the  course  of  a  few  months,  but 
curiously  enough  in  the  same  medium  the  green  colour  of  closely 
allied  species  will  remain  fairly  good.  Very  often  saprophytic 
algae  will  retain  their  colour  perfectly,  while  the  moss  has 
altogether  parted  with  it. 

There  appears  to  be  no  necessity  for  "  fixing  "  the  specimens 
before  mounting  ;  but  with  leaves  of  comparatively  delicate  struc- 
ture it  is  often  advantageous  to  do  so  unless  the  mounting  medium 
contains  a  fixing  agent,  and  I  have  had  very  good  results  with 
the  complanate  branches  of  such  species  as  Plagiothecium  elegans 
and  Plagiothecium  depressum  by  fixing  them  in  picric  acid  before 
mounting  in  glycerine  jelly,  the  picric  being  washed  out  previous 
to  mounting.  With  such  a  species  as  Plagiothecium  depressum, 
which  bears  very  characteristic  bunches  of  deciduous  flagellae  on 
its  branches,  every  care  has  to  be  exercised  to  avoid  detaching 
the  flagellae,  whose  particular  mission  it  is  to  become  detached 
with  the  slightest  provocation.  Such  is  the  case  with  many 
species  of  Tortula,  the  leaves  of  which  bear  characteristic  gemmae. 
The  extremely  beautiful  bunches  of  gemmae  at  the  apices  of 
Ulota  phyllantha,  and  the  scattered  gemmae  on  the  leaves  of 
Orthotrichum  Lyellii,  are  other  instances.  It  is  only  the  novice 
who  will  attempt  to  "clean"  such  leaves;  the  confirmed  bryologist 
is  too  thankful  to  get  the  leaves  mounted  with  the  appendages 
adhering  to  worry  over  a  small  amount  of  adventitious  matter. 


IN    BRYOLOGICAL    WORK.  529 

The  air  contained  in  the  cork-like  cells  of  Leucobryum  glaucum, 
and  other  species  with  inflated  cells,  is  often  very  difficult  to  dis- 
charge. Boiling  gets  rid  of  a  certain  amount,  especially  if  the 
leaves  are  left  in  the  de-aerated  water  for  a  day  or  two,  with  re- 
boiling  at  intervals.  Obstinate  cases  require  exhausting  with  an 
air  pump.  The  leaves  of  the  Sphagnaceae  are  especially  difficult 
if  the  moss  is  once  allowed  to  become  thoroughly  dry  and  the 
cells  filled  with  air.  I  make  a  point  of  mounting  these  as  soon 
as  collected,  or,  at  any  rate,  of  keeping  the  stems  saturated  with 
water  until  I  can  attend  to  them.  Bryologists  attach  very  great 
importance  to  the  basal  areolation,  and  it  is  necessary  that  the 
leaves  should  come  away  from  the  stem  quite  complete  and  un- 
injured, but  it  is  not  at  all  a  simple  matter  to  detach  the  leaves 
from  the  stems  previous  to  mounting  them.  With  strongly 
decurrent  leaves,  such  as  exist  in  Mnium  stellare  and  in  some 
Hypna,  it  is  almost  impossible  to  obtain  perfect  specimens,  and 
it  is  better  to  remove  several  of  the  adjacent  leaves,  and  mount  a 
portion  of  the  stem  with  the  leaf  in  situ.  Generally,  the  most 
satisfactory  way  of  removing  a  leaf  is  to  take  hold  of  the  apex 
with  a  fine  pair  of  forceps,  and,  holding  the  branch  with  another 
pair,  very  gradually  to  strip  the  leaf  from  the  stem  in  a  down- 
ward direction.  Mosses  with  filiform  stems  and  distant  leaves 
such  as  Amblystegium  serpens,  can  be  studied  by  mounting  the 
stem  with  the  leaves  attached.  The  strongly  falcate  and  circin- 
nate  leaves  of  Harpidioid  Hypna  are  very  unmanageable,  and  I 
usually  strip  a  considerable  number  of  leaves  from  the  stem,  and 
mount  the  lot  as  a  "  spread  "  slide,  trusting  largely  to  luck  to 
arrange  some  of  them  in  a  suitable  position  for  examination. 
This  is  obviously  a  reckless  method,  but  it  answers  very  well. 

A  certain  amount  of  section  cutting  is  necessary  to  the  syste- 
matic bryologist,  apart  from  any  histological  investigation.  The 
leaves  of  the  Polytrichaceae,  for  instance,  have  the  surface 
covered  with  longitudinal  lamellae  consisting  of  rows  of  upright 
moniliform  filaments.  Prof.  Lindberg  was  the  first  to  point 
out  that  these  formed  a  valuable  aid  in  diagnosing  the  different 
species,  as  the  transverse  number  and  shape  of  the  terminal  cell 
differ  in  each  species.  The  only  way  in  which  they  can  be  satis- 
factorily examined  is  by  means  of  a  transverse  section. 

The  section  Aloidea  of  the  Tortulaceae  also  has  lamelliferous 
leaves,    of   which   sections   are    necessary.      The   quickest    and 


530  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

simplest  way  is  to  cut  the  sections  in  an  ether-freezing  microtome, 
and  extremely  thin  sections  are  not  demanded,  but  as  the  sections 
must  be  cut  at  right  angles  to  the  axis  of  the  leaf,  some  care 
in  orientating  the  leaf  has  to  be  taken.  Sections  of  stems  are 
also  required  in  determining  species  of  Sphagnaceae,  but  these 
are,  of  course,  a  simple  matter. 

In   dealing  with   the    capsule   of   the   moss   two   methods   of 
mounting  may  be  employed  for  the  study  of  the  peristome.     It 
may  be  mounted  dry  as  an  opaque  object,  or  in  some  medium 
as   a   transparent    one.       Mounted    dry   and    illuminated   with 
reflected    light    the    peristome  is  the  only  concession   the   moss 
world  makes  to  spectacular  effect.     For  purposes  of  study,  how- 
ever, the  limitations  of  this  method  are  great,  and  the  student  is 
forced  to  adopt  transparent  mounting.     At  the  same  time  dry 
mounts  of  some  peristomes  are  quite  useful  to  the  bryologist  in 
getting  at  the  general  appearance  ;  the  sulcae  of  the  Orthotrichum 
capsule  and  the  cilia  of  its  endostome  are  quickly  and  satisfactorily 
exhibited  as  an  opaque  object  under  the  binocular  microscope. 
For  anything  like  detailed  study,  however,  the  peristome  must  be 
mounted  as  a  transparent  object.     A   good   deal  depends  upon 
getting  the  capsule  in  the  right  condition.     It  should  be  quite 
ripe,  so  that  the  touch  of  a  needle  at  the  junction  of  the  operculum 
with  the  capsule  will  liberate  the  lid  and  enable  the  peristome 
to  unfold  without  injury.     If  the  lid  has  to  be  forced  away  some 
of  the  teeth  of  the  peristome  usually  go  with  it.     To  prepare  it 
for  mounting,  the  capsule  may  be  severed  transversely  about  the 
middle,  then  a  longitudinal  slit  made  through  the  annular  ring 
and  that  portion  of  the  capsule  wall  adhering ;  this  permits  of  the 
peristome    being  spread  out  flat.      The  spores  require  washing 
away,  though  it  is  an  advantage  if  some  of  them  adhere  to  the 
teeth,  as  they  often  afford  valuable  specific  characters.     If  the 
capsule  has  already  shed  its  spores  when  gathered,   but  is  not 
dilapidated,  it  is  often  in  a  very  favourable  condition  for  mount- 
ing, and  in  those  mosses  with  a  double  peristome  the  endostome 
can  often  be  detached  and  mounted  separately  from  the  exostome  ; 
this  enables  the  cilia  so  often  present  in  double  peristomes  to  be 
studied  to  the  best  advantage.     When  the  cut  peristome  has  been 
laid  flat  and  judiciously  cleaned  it  should  be  subjected  to  a  cover 
slip  and  spring  clip  for  a  day  or  two,  glycerine  and  water  being 
run  under  by  capillary  attraction.     The  annular  cells  are  usually 


IN    BRYOLOGICAL    WORK  531 

so  elastic  that  some  difficulty  is  found  in  keeping  the  peristome 
flat  when  it  is  mounted  unless  pressure  has  been  previously  applied. 
Glycerine  jelly  or  Farrant's  medium  are  the  most  convenient 
mountants.  There  is  really  no  particular  reason  why  the  peristome 
should  be  mounted  in  its  entirety,  as  a  sector  of  it  serves  all  useful 
purposes  and  is  very  much  more  easily  managed  ;  that  is  to  say, 
there  is  no  additional  knowledge  gained  by  mounting  the  whole 
thirty-two  teeth  of  a  double  peristome  when  a  sector  embracing 
four  each  of  the  outer  and  inner  teeth  will  enable  all  structural 
details  to  be  made  out.  The  tubular  teeth  of  the  Tortulaceae  can 
only  be  mounted  en  bloc  ;  the  basal  membrane  is  the  point  of 
interest,  and  so  long  as  this  can  be  clearly  made  out  the  rest  does 
not  matter. 

In  some  species  the  teeth  of  the  peristome  are  extremely 
fragile,  and  it  is  rarely  possible  to  get  satisfactory  mounts  of 
them  if  one  relies  on  finding  a  perfect  specimen  in  a  chance 
gathering.  I  believe  the  only  way  is  to  bring  home  unripe 
specimens  and  carefully  ripen  them  under  observation,  so  that 
the  capsule  can  be  mounted  as  soon  as  the  ripe  operculum  falls. 

The  capsules  of  the  Orthotrichaceae  bear  very  important  char- 
acters in  the  presence  of  stomatic  cells.  These  are  of  two  forms ; 
in  the  one  they  are  seated  in  the  cuticle  only  and  are  "  superficial," 
in  the  other  they  are  buried  in  the  wall  of  the  capsule  and  are 
"  immersed."  To  get  a  good  view  of  them  the  capsule  is  slit  up 
and  the  spore  ^ac  removed.  The  capsule  is  then  spread  out  on 
a  slide,  cuticular  side  uppermost,  and  mounted  in  glycerine  jelly. 
The  stomata  are  said  usually  to  be  found  in  the  lower  half  of 
the  capsule,  and  they  are  certainly  always  found  there  in  the 
books ;  but  occasionally  nature  seems  to  ignore  her  own  boundaries, 
for  I  have  seen  them  scattered  here  and  there  over  the  capsule, 

As  I  have  previously  stated,  a  student's  collection  of  slides 
would  be  no  incentive  whatever  to  any  one  to  take  up  the  study 
of  mosses.  At  the  same  time  I  can  imagine  no  more  valuable 
collection  than  a  reference  series  of  slides  of  closely  allied  species, 
and  species  subject  to  wide  variation.  The  determination  of 
species  and  varieties  in  the  moss  flora  has  become  a  matter  of 
extreme  difficulty,  thanks  to  the  efforts  of  specialists  in  various 
groups,  and  even  an  advanced  worker  is  glad  of  anything  that 
looks  like  finality.  Fifty  years  ago  English  bryologists  con- 
sidered themselves  well  served  with  ten  species  of  Sphagna,  the 


532  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

separation  of  which  was  no  great  strain  on  one's  mental  powers. 
At  the  present  time  it  is  useless  to  touch  the  group  unless  you 
are  prepared  to  distinguish  between  at  least  forty  species,  with 
an  average  of  four  varieties  each.  Of  Sphagnum  acutifolium 
alone  Warnstorf  describes  sixty  varieties,  and  I  believe  that  very 
few  even  critical  bryologists  would  care  to  rely  on  their  own 
diagnosis  of  them.  It  will  be  seen  from  this  how  valuable  an 
authenticated  collection  of  slides  would  be  to  the  bewildered 
student. 

It  will  perhaps  be  desirable  to  state  that  the  nomenclature 
adopted  in  naming  the  slides  is  that  of  the  second  edition  of 
Dixon's  Student's  Handbook  of  British  Mosses.  1  believe  that 
Dr.  Braithwaite's  magnificent  monograph  is  in  the  library  of  the 
Quekett  Microscopical  Club,  and  my  first  intention  was  to  take 
that  as  my  guide  j  but  Dixon's  Handbook  is  now  so  generally 
used,  and  is  so  compact,  that  it  would  probably  be  the  book 
selected  by  any  one  who  decided  to  take  up  the  study  of  the 
mosses ;  and  I  may  say  that  the  critical  comparisons  in  it 
between  closely  allied  species  are  extremely  useful  to  the  student 
working  alone. 


IN    BRYOLOGICAL    WORK.  533 


Notes  on  a  Collection  of  Slides  of  Mosses. 

Polytrichum  formosum. 

Sections  of  a  leaf  cut  to  show  the  jointed  appendages  that 
constitute  the  lamellae.  These  appendages  are  of  great  use  in 
determining  the  species,  as  the  form  of  the  terminal  cell,  the 
number  of  cells  in  each  appendage,  and  the  average  number  of 
appendages  in  the  transverse  section  differ  with  the  species. 

Ceratodon  purpureus 

A  common  moss  in  dry  woods,  on  sandy  banks,  etc.,  but  also 
a  very  polymorphous  moss.  In  spite  of  considerable  leaf 
variation,  however,  a  distinct  and  constant  feature  is  the 
recurved  margin,  becoming  plane  immediately  below  the  apex, 
which  is  usually  toothed.  The  characteristic  annulus  is  well 
shown  in  the  slide. 

Dicranum  majus. 

A  fine  moss  usually  occurring  in  mountainous  woods.  The 
common  and  variable  Dicranum  scoparium  in  some  of  its  forms, 
which  are  chiefly  barren,  approaches  it  very  closely.  Dicranum 
majus,  however,  bears  a  multiple  number  (2-5)  of  setae  from 
one  perichaetium.  Both  species  belong  to  the  section  Eu- 
Dicranum,  which  is  characterised  by  the  leaves  having  lateral 
pores  connecting  the  cells  in  the  lower  part  of  the  leaf. 

Leucobryum  glaucum. 

An  interesting  moss,  the  leaves  of  which  are  well  worth 
careful  examination.  The  chlorophyll  cells  are  masked  by  an 
outer  layer  of  hyaline,  inflated  corky  cells  communicating  by 
pores.  The  greater  portion  of  the  leaf  is  composed  of  the  nerve. 
Cardot  has  monographed  the  genus,  see  his  Recherches  Anatomiques 
sur  les  Leucobryacees.  It  is  a  not  uncommon  moss  on  dry,  turfy 
ground,  but  the  fruit  is  very  rare,  and  according  to  my  experience 
found  chiefly  when  the  moss  grows  in  quite  damp  localities.  A 
curious  state  of  the  moss  occurs  in  dry  woods  in  which  it  forms 
small   rounded   cushions,  quite   detached    from  the  ground,  and 


534  G.    T.    HARRIS    ON    MICROSCOPICAL    METHODS 

easily  transported  by  strong  winds  or  contact  with  moving 
objects.  The  leaves  are  easily  detached  and  often  bear  at  their 
tips  tufts  of  radicles  which  give  rise  to  new  plants. 

Fissidens  exilis. 

One  of  the  smallest  species  of  the  Fissidentaceae  and  readily 
known  by  its  non-bordered  leaves. 

Fissidens  viridulus. 

Known  from  the  preceding  by  its  leaves  having  a  narrow 
border  to  them,  but  the  variety  Lylei  has  the  border  wanting 
except  on  the  sheathing  laminae. 

Fissidens  algarvicus. 

I  am  able  to  include  a  specimen  of  this  new  British  moss  through 
the  kindness  of  Mr.  G.  B.  Savery,  its  discoverer  in  England. 
It  comes  near  Fissidens  pusillus,  and  so  far  has  only  been  found 
in  two  localities,  Silverton  in  Devonshire,  where  Mr.  Savery  first 
discovered  it,  and  near  Cheltenham.  It  is  characterised  by  its 
narrow  acute  leaves  with  rather  strong  and  narrow  border. 

Fissidens  bryoides. 

An  extremely  common  and  variable  species,  the  forma  in- 
constans  was  originally  a  separate  species,  but  is  now  generally 
considered  to  be  merely  a  "  form  "  of  F.  bryoides.  As  will  be 
seen  from  the  two  slides,  the  difference  is  considerable  in  general 
appearance,  and  I  have  found  the  form  inconstans  to  be  little 
subject  to  variation  from  widely  different  localities. 

Rhacomitrium  lanuginosum. 

This  is  the  largest  British  species  of  the  Grimmiaceae,  and 
often  covers  immense  tracts  of  mountain  moorland  with  great 
masses.  The  hyaline  and  papillose  serrated  leaves  are  very 
beautiful. 

Hedwigia  ciliata. 

Another  inhabitant  of  dry,  rocky  localities,  with,  as  is  usually 
the  case  with  such   mosses,  hyaline  apices  to  its  leaves.     The 


IN    BRYOLOGICAL    WORK.  535 

perichaetial   bracts  are    ciliated,   as  may   be   seen    in    the    slide, 
whence  the  specific  name. 

Pottia  lanceolata. 

The  Pottias  are  usually  without  peristomes,  but  the  present 
species  is  a  notable  exception,  in  that  it  possesses  a  highly 
developed  one. 

Pottia  truncatula. 

A  gymnostomous  form  readily  known  by  the  truncate  capsule 
with  wide  mouth,  and  by  the  columella  being  attached  to  the  lid 
and  falling  with  it. 

Barbula  lurida. 

This  is  essentially  a  calcareous-loving  species,  and  is  considen  d 
very  rare  in  fruit.  The  peristome  is  very  fragile,  and  it  is 
difficult  to  obtain  good  specimens. 

Ulota  phyllantha. 

Readily  known  by  the  clusters  of  brown  gemmae  borne  at  the 
apices  of  the  leaves.  The  fruit  is  extremely  rare,  and  has  only 
been  found  once  or  twice  in  Eno-land. 


i»4 


Orthotrichum  Lyellii. 

This  also  may  be  readily  known  by  the  brown  gemmae,  which 
in  this  species  are  scattered  generally  over  the  surface  of  the 
leaves.     It  rarely  fruits. 

Orthotrichum  diaphanum. 

The  capsule  wall  of  this  species  shows  the  "immersed"  stomata, 
and  should  be  compared  with  the  slide  of  Orthotrichum  affine, 
which  shows  "  superficial "  stomata.  The  two  forms  are  very 
useful  in  diagnosing  the  species  of  this  difficult  genus.  The  outer 
"  superficial "  cells  are  well  shown  in  the  slide,  and  the  reniform 
"  guard "  cells  may  be  brought  into  view  by  focusing  down 
through  the  superficial  cells. 


536      G.  T.  HARRIS,  MICROSCOPICAL  METHODS   IN   BRYOLOGICAL  WORK. 

Brachythecium  rutabulum. 

One  of  the  commonest  and  most  variable  of  the  British  mosses. 
The  type  is  not  difficult  to  recognise,  but  the  varieties  with  very 
acuminate  leaves  are  difficult  to  determine,  especially  when 
barren,  as  they  often  are. 

Hypnum  cupressiforme. 

This  again  is  a  very  variable  form,  and  its  varieties  differ 
widely  from  the  type.  The  var.  resupinatus  has  had  specific 
rank  from  many  authorities,  but  it  certainly  differs  no  more 
from  the  type  than  does  the  var.  jUiforme. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  A'o.  76,  April  1915. 


537 


PROCEEDINGS 

OF    THE 

QUEKETT    MICROSCOPICAL  CLUB. 

At  the  501st  Ordinary  Meeting  of  the  Club,  held  on  October  27th, 
1914,  the  Vice-President,  Mr.  D.  J.  Scourfield,  F.Z.S.,  F.R.M.S., 
in  the  chair,  the  minutes  of  the  meeting  held  on  June  23nd  were 
read  and  confirmed. 

Messrs.  Samuel  Ernest  Loxton  and  W.  Beattie  were  balloted 
for  and  duly  elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks  of 
the  members  voted  to  the  donors. 

Two  series  of  Dr.  Sigmund's  histological  preparations  with 
descriptions  and  sixty-one  slides  were  added  to  the  Cabinet. 

The  Chairman  read  a  letter  conveying  the  information  of  the 
death  of  Dr.  Arthur  Mead  Edwards,  of  Newark,  New  Jersey, 
U.S.A.,  which  took  place  on  September  13th,  1914.  Dr.  Edwards 
was  the  oldest  honorary  member,  having  been  elected  in  January 
1868.  He  was  at  that  time  President  of  the  American  Micro- 
scopical Society  of  New  York.  At  his  death  he  was  seventy- 
eight  years  of  age.  His  chief  microscopic  work  was  in  the 
study  of  the  Diatomaceae.  His  communications  are  still  re- 
membered by  some  of  the  older  members. 

The.  report  from  the  Club's  delegate — Mr.  C.  F.  Rousselet, 
F.R.M.S. — to  the  conference  of  the  delegates  of  the  corre- 
sponding societies  of  the  British  Association  at  Havre  was  read 
by  the  Secretary.  The  Congress  began  on  Monday,  July  27th. 
Mons.  A.  Gautier,  the  President,  welcomed  the  members,  and 
delivered  an  address.  On  behalf  of  the  English  members,  Sir 
W.  Ramsay  addressed  the  meeting  in  French.  On  Tuesday  there 
was  a  conference  of  delegates  in  the  Town  Hall.  Sectional 
meetings  took  place  on  that  day  and  on  Wednesday.  On  Thurs- 
day, the  30th,  an  excursion  up  the  Seine  as  far  as  Rouen,  visiting 
various  historical  places  on  the  way,  was  made.  On  Friday 
meetings  were  held,  but,  owing  to  the  threatening  political  out- 
look, were  poorly  attended.  On  Saturday,  August  1st,  the 
Government  decree  of  general  mobilisation  was  given,  and  the 
Journ.  Q.  M.  C,  Series  II.— No.  76.  37 


538  PROCEEDINGS    OF   THE 

conference,  which  had  been  much  hampered  by  the  political 
unrest,  hurriedly  broke  up.  The  Chairman  tendered  the  Club's 
thanks  to  Mr.  Bousselet  for  his  report,  and  congratulated  him  on 
his  safe  return. 

A  paper  by  Mr.  A.  A.  C.  Eliot  Merlin,  F.R.M.S.,  was  read  (in 
part)  on  "  The  Minimum  Visible."  It  commenced :  "  I  have 
read  with  great  interest  and  profit  our  President's  address  on 
1  Organisms  and  Origins.'  The  subject  is  one  that  must  fascinate 
every  microscopist,  whatever  his  line  of  research.  In  the  address 
the  point  was  raised  respecting  the  minimum  visible,  it  being 
stated  that  '  it  seems  impossible  to  obtain  any  precise  information 
as  to  the  size  of  the  smallest  particles  that  can  be  seen  with  the 
microscope.'  Now,  setting  aside  the  ultra-microscope,  as  our 
knowledge  is  very  exact  and  definite  indeed  on  this  subject,  it 
may  prove  of  interest  to  deal  with  the  question  at  some  length. 
As  a  matter  of  fact,  when  a  particle  properly  illuminated  is  just 
visible  with  a  given  objective,  if  the  aperture  be  cut  down  by 
means  of  an  iris  diaphragm,  placed  above  the  back  lens,  so  that 
the  particle  just  ceases  to  be  visible,  and  the  N.A.  to  which  the 
objective  has  been  reduced  is  measured,  then  the  dimensions  of 
the  particle  can  be  exactly  ascertained  from  the  antipoint  table 
published  by  Mr.  Nelson  in  the  Journal  of  the  Royal  Microscopical 
Society.  This  antipoint  table  should  prove  invaluable  when 
accurate  and  minute  measurements  are  necessary." 

A  recent  paper  by  Mr.  N.  E.  Brown,  A.L.S.,  "  Some  Notes  on 
the  Structure  of  Diatoms,"  was  referred  to,  in  which  Mr.  Brown 
stated  that  he  had  seen  pores  on  the  surface  of  certain  diatoms 
which  he  estimated  at  1/200, 000th  of  an  inch  in  diameter.  Mr. 
Merlin,  examining  some  of  the  diatoms  under  a  very  perfect 
^  apochromat,  N.A.  1'4,  employed  with  a  magnification  of 
4,200,  readily  distinguished  these  pores,  but  in  them  so  resolved 
believed  he  immediately  recognised  Dr.  Boyston  Pigott's  "  dark 
eidolic  dots  of  interference." 

In  speaking  on  the  subject  of  Mr.  Merlin's  paper,  Mr. 
N.  E.  Brown  said :  "  If  I  understand  Mr.  Merlin  correctly,  the 
two  points  in  it  which  call  for  any  remark  from  myself  are 
that  the  structures  I  have  conceived  to  be  pores  were  discovered 
by  Dr.  Boyston  Pigott  many  years  ago,  and  considered  by  him 
due  to  interference.  I  much  regret  that  I  have  not  read  Dr. 
Boyston  Pigott's  paper,  or  I  should  have  referred  to  it  in  my 


QUEKETT   MICROSCOPICAL    CLUB.  539 

recent  notes.  But  I  certainly  cannot  agree  that  these  structures 
are  myths  without  substance.  I  still  maintain  that  they  are 
very  real  structures.  I  take  it  that  if  they  were  interference 
figures,  they  could  only  be  formed  when  the  dots  from  which 
they  are  supposed  to  emanate  are  regularly  placed,  equally  spaced 
and  of  the  same  size,  also  that  under  different  conditions  of 
illumination  or  the  shifting  of  the  mirror  they  would  alter  their 
position  or  form.  But  this  is  by  no  means  the  case.  In  most 
diatoms  the  dots  are  regular  in  position  and  size,  but  on  some 
portions  of  the  shell  of  Nitzschia  scalaris  regular  rows  of  small 
dots  and  diverging  rows  of  much  larger  dots  may  be  found  side 
by  side,  and  some  of  the  dots  in  the  diverging  rows  are  often 
quite  irregularly  placed,  yet  the  structures  I  suppose  to  be  pores 
are  regularly  placed  along  the  middle  of  the  space  between  the 
rowrs  in  each  case,  or,  where  very  widely  diverging,  the  row  of 
pore-structures  forks.  Also  they  do  not  shift  their  position 
under  varying  conditions  of  illumination ;  they  can  be  seen  alike 
and  in  the  same  position  with  axial  illumination  and  a  full  cone 
or  small  cone  of  light,  with  annular  illumination,  with  oblique 
illumination  in  one  azimuth  arranged  either  parallel  with  or 
transverse  to  the  rows  of  dots,  with  either  a  chromatic  Powell 
and  Lealand  or  an  Abbe,  or  an  achromatic  Powell  and  Lealand 
substage  condenser.  Surely  identical  myths  could  not  be  pro- 
duced under  all  these  conditions." 

Mr.  Ainslie,  while  pointing  out  the  impossibility  of  any 
detailed  criticism  until  opportunity  had  been  obtained  for  care- 
fully going  through  the  statements,  remarked  that  size  alone  by 
no  means  determined  the  limits  of  visibility  :  the  quality  of  an 
object,  its  opacity  or  transparency,  and  other  factors,  would 
affect  the  matter.  He  gave  some  instances  where  structures  had 
been  distinctly  seen  which  were  far  smaller  than  what  is 
scientifically  considered  the  minimum  required  for  visibility.  On 
the  proposal  of  the  Chairman,  a  very  hearty  vote  of  thanks  to 
Mr.  Merlin  for  his  valuable  communication  was  recorded. 

Mr.  Rousselet  exhibited  under  microscopes  two  species  of  African 
Volvox.  These  had  a  somewhat  remarkable  history.  In  October 
1910  a  paper  by  Prof.  G.  S.  West,  of  Birmingham  University, 
was  read,  in  which  two  new  species  of  Volvox  from  Africa  are 
described.  One,  V.  Africanus,  had  been  collected  by  Mr.  It.  T. 
Leiper,  of  the  Egyptian  Government  Survey,  from  the  north  part 


540  PROCEEDINGS    OF    THE 

of  Lake  Albert  Nyanza.  The  other,  V.  Rousseleti  (named  in 
honour  of  its  discoverer),  was  obtained  by  Mr.  C.  F.  Rousselet  on 
the  occasion  of  the  visit  of  the  British  Association  to  South  Africa 
in  1905,  from  a  pool  formed  by  the  Gwaai  River,  near  the  railway- 
station.  In  both  cases  only  asexual  vegetative  individuals  were 
acquired,  with  the  result  that  a  complete  description  could  not  be 
given,  in  1913  Mr.  Rousselet  received  from  Dr.  Jakubski,  of 
the  Zoological  Institute  of  Lemberg  University,  some  tubes  con- 
taining plankton  material  collected  in  German  East  Africa.  In 
two  of  these  tubes,  among  other  objects,  Mr.  Rousselet  was 
surprised  to  come  across  numerous  colonies  of  Vol  vox,  which  he 
at  once  recognised  as  the  same  two  species  already  described  by 
Prof.  West.  Fortunately,  in  this  case,  both  species  were  present 
in  their  various  sexual  stages,  with  androgonidia  and  oospores,  as 
well  as  the  vegetative  colonies.  It  will,  therefore,  now  be  possible 
to  complete  the  description  of  both  species.  A  tragic  note  is 
given  to  the  episode  by  the  fact  that  Mr.  Rousselet  returned,  as 
requested,  the  tubes  and  specimens  to  Prof.  Jakubski  at  Lemberg 
early  in  July;  but  owing  to  the  war  and  the  occupation  of 
Lemberg  by  the  Russian  Army  soon  after  they  should  have 
arrived,  he  has  not  been  able  to  ascertain  whether  they  safely 
reached  their  destination,  or  what  has  become  of  them,  or  of  the 
correspondent  to  whom  they  were  addressed.  A  vote  of  thanks 
to  Mr.  Rousselet  for  his  interesting  communication  was  carried 
by  acclamation. 

Mr.  W.  E.  Watson  Baker  exhibited  under  a  microscope  a 
mounted  specimen  of  the  egg  of  the  Anopheles  mosquito  and  a 
very  young  larva  of  the  same.  The  organism  is  rarely  found  in 
these  conditions ;  but  the  Secretary  mentioned  that  on  two 
occasions  last  year,  at  excursions  of  the  Club,  he  had  obtained 
specimens  of  nearly  mature  larvae.  In  one  of  the  instances  he 
had  been  able  to  feed  the  creature — they  devour  some  of  the 
smaller  algae — till  it  pupated,  and  finally  the  perfect  insect 
emerged.  The  meeting  thanked  Mr.  Watson  Baker  for  his 
beautiful  exhibit. 


At  the  502nd  Ordinary  Meeting  of  the  Club,  held  on  November 
24th,  the  President,  Prof.  Arthur  Dendy,  D.Sc,  F.R.S.,  in  the 
chair,  the  minutes  of  the  meeting  held  on  October  27th  were 
read  and  confirmed. 


QUEKETT    MICROSCOPICAL    CLUB.  541 

Messrs.  Walter  Adams,  George  Clarendon  Hamilton,  F.  Rear- 
don  Brokenshire,  W.  Ludlow  Haynes,  Alexander  McTavish, 
W.  B.  Tindall,  Henry  Jewell  and  the  Rev.  John  Bruce  Williams 
were  balloted  for  and  duly  elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks  of 
the  members  voted  to  the  donors. 

The  President  called  upon  the  meeting  to  pass  a  resolution 
expressing  the  members'  deep  regret  at  the  loss  they  had  sustained 
by  the  death  of  Dr.  M.  C.  Cooke,  M.A.,  LL.D.,  A.L.S.,  which 
occurred  on  November  12th  at  his  residence  in  Southsea. 

Dr.  Mordecai  Cubitt  Cooke  was  born  July  12th,  1825,  at  the 
village  of  Horning,  in  Norfolk.  From  an  early  age  dependent 
upon  his  own  resources,  he  was  in  turn  employed  as  draper's 
assistant,  teacher  in  a  National  school,  and  lawyer's  clerk.  As 
an  assistant  in  the  Indian  Museum  he  at  last  found  congenial 
occupation,  and  on  the  abolition  of  that  institution  he  spent  some 
time  at  South  Kensington  Museum.  He  afterwards  joined  the 
Herbarium  at  the  Royal  Botanical  Gardens,  Kew,  and  was  for 
twelve  years  (1880-1892)  in  charge  of  the  Cryptogamic  Depart- 
ment. In  1892  he  retired.  During  this  time  he  incorporated 
his  own  herbarium,  which  contained  46,000  specimens,  with  the 
existing  collection  at  Kew,  as  well  as  the  collection  of  fungi  pre- 
sented to  Kew  by  the  Rev.  M.  J.  Berkeley.  His  figures  of 
fungi,  mostly  coloured,  and  numbering  25,000  plates,  are  also 
at  Kew. 

His  first  important  work  was  the  Handbook  of  British  Fungi 
(1871),  followed  by  Mycographia,  Handbook  of  Australian  Fungi, 
and  Illustrations  of  British  Fungi  (with  1,200  coloured  plates). 
He  was  editor  of  Hardwicke's  Science  Gossip  from  its  beginning 
in  1865  until  December  1871.  Dr.  Cooke,  the  "  father  of  the 
Club,"  was  one  of  the  eleven  members  who  attended  the  pre- 
liminary meeting  of  the  Q.M.C.,  held  on  June  14th,  1865,  and  he 
was  elected  one  of  its  first  vice-presidents.  He  was  president  in 
1882  and  1883,  and  was  elected  an  honorary  member  in  1893. 

Mr.  J.  Grundy  introduced  and  explained  the  great  advantages 
of  a  micrometric  table  by  Mr.  E.  M.  Nelson.  The  table  is  similar 
to  logarithm  tables,  the  cross  marginal  numbers  being  M  and  O 
respectively.  The  table  gives  the  value  of  O  x  100/M.  M  is 
the  reading  of  one  division  of  a  stage  micrometer  in  the  divisions 
of  the  eyepiece  micrometer.     O  is  the  reading  of  the  object  to  be 


542  PROCEEDINGS    OF    THE 

measured  in  the  divisions  of  the  eyepiece  micrometer.  To  find 
the  size,  take  in  the  table  on  the  M  column  the  number  repre- 
senting the  reading,  and  the  number  in  that  line  vertically  below 
the  reading  in  the  0  line  will  be  the  size  of  the  object  in  microns. 
Example  :  0*1  mm.  of  stage  micrometer  spans  28  divisions  of  the 
eyepiece  micrometer.  M  is  then  28.  An  object  measures  19 
divisions  of  the  eyepiece  micrometer.  O  is  then  19.  Utilising 
the  table,  the  size  will  be  found  at  once — viz.  68  //,.  Should  the 
measured  division  or  unit  of  the  stage  micrometer  be  001  mm.,  it 
is  only  necessary  to  move  the  decimal-point  one  place  to  the  left 
in  the  final  reading,  which  would  give  the  result  in  the  example 
above  as  6*8/x.  Similarly,  if  the  measured  unit  of  the  stage 
micrometer  had  been  1  mm.,  then  it  would  be  necessary  to  place 
a  cipher  after  the  figures  given  in  the  table ;  so  in  the  same 
example  the  object  would  have  been  680  jx.,  or  0*68  mm.  When 
the  unit  of  the  stage  micrometer  is  0*1  in.,  the  decimal-point  must 
be  moved  three  places  to  the  left ;  with  a  unit  of  0*01  in.,  four 
places;  and  with  a  unit  of  0*001  in.  five  places  to  the  left.  In 
the  example  above,  the  object  would  measure  0*068  in.,  0*0068  in., 
0*00068  in.  respectively.  The  table  is  published  by  Messrs.  H.  F. 
Angus  &  Co.,  83,  Wigmore  Street,  London,  W.,  price  3d. 

The  President  said  they  were  very  greatly  indebted  to  Mr. 
Nelson  for  this  table,  and  to  Mr.  Grundy  for  putting  the  matter 
before  them  in  the  way  he  had  done.  For  his  own  part  he  would 
welcome  anything  which  saved  him  from  multiplication,  and  he 
should  imagine  from  what  he  had  heard  that  this  was  a  sort  of 
ready  reckoner  for  the  microscope,  and  would  be  extremely  useful 
to  any  one  who  had  many  measurements  to  make.  He  thought 
he  should  find  a  great  use  for  it  in  checking  his  own  results  by 
comparison. 

Mr.  Ainslie  thought  that  the  table  promised  to  be  extremely 
useful  to  those  who  wished  to  make  measurements  of  minute 
objects.  If,  however,  instead  of  28  they  happened  to  find  28*7  or 
29*3  it  would  merely  be  necessary  to  alter  the  tube  length  so  that 
the  stage  micrometer  below  covered  a  certain  value  of  the  eyepiece 
micrometer. 

In  measuring  diatoms  the  tube  length  must  be  adjusted,  and 
having  determined  that,  they  must  be  careful  not  to  touch  the 
correction  collar,  as  that  would  at  once  alter  the  power  of  the 
objective. 


QUEKETT   MICROSCOPICAL    CLUB.  543 

Mr.   D.  J.  Scourfield,  F.Z.S.,  F.R.M.S.,  read  a  paper  upon  a 
new  Copepod  found  in  water  from  hollows  on  tree-trunks,     He 
stated  that  in  recent  years,  owing  to  the  endeavour  to  discover 
the  life-histories  of  mosquitoes  and  other  insects  supposed  to  be 
connected    with    the   dissemination   of    tropical    diseases,    much 
attention   had  been  given  to   the  subject,   and,  according  to  a 
recent  paper  published  by   Picado,  no  less  than  250   species  of 
animals   have  been    found   living  in  this  peculiar  environment, 
forty-nine  being  new  to  science.     They  belonged  to  almost   all 
groups  of   invertebrates ;  but  naturally  insects  and  their  larvae 
predominate.     Mr.   Scourfield  pointed  out  that  in  tropical  forests, 
ponds  and  water  on  the  ground  are  rarely  met  with,*this  making 
it  difficult  to  locate  the  breeding-places  of  mosquitoes,  etc.,  until 
it   was  found  that  incubation  took  place  in  water  contained  in 
little  cups  in  tree-trunks  and  roots.     He  first  commenced  to  look 
for  Entomostraca  in  these  situations  after  reading  the  celebrated 
Fritz  Miiller's  description  of  a  new  Ostracod  representing  a  new 
genus,  Elpidium  bromeliarum,  which  occurred  almost  constantly 
in  association  with  the   Bromeliaceous  plants  in  the  forests  of 
Brazil,    and,    strangely  enough,   was   to   be   found   in  no  other 
situation.     His  curiosity  was  rewarded  by  finding  the  remarkable 
blind  Copepod,  Belisarius  viguieri,  which  had  not  previously  been 
found  in  this  country.     He  was  able  to  report  that  on  several 
occasions  he  had  found  a  new  Copepod  in  such  little  reservoirs  of 
water  on  trees  in  Epping  Forest,  and  up  to  the  present  they  have 
been  found  nowhere  else.     The  new  species  evidently  belongs  to 
the  Harpacticid  genus  Moraria,  described  by  T.  and  A.  Scott, 
found   in    Loch    Morar,    Scotland.       Eight  species    are   known, 
three  of  which  have  been  found  in  the  British  Isles.     He  stated 
that  he  proposed  to  call  it  Moraria  arhoricola,  because  of  its  tree- 
d welling  habit.     It  is  a  very  small  form,  the  female  measuring 
only  about  1/40  in.  in  length,  of  the  type  of  Cyclops,  Cantho- 
campus  and  Diaptomus.      The  genus    is  peculiarly  adapted   to 
exist  in  but  little  water,  and,  when  placed  in  this  element,  wriggles 
rather  than  swims.     In  Mr.  Scour-field's  experience,  it  is  mostly 
found  in  the  early  part  of  the  year.     He  commented  upon  their 
wonderful  vitality.     In  one  case,  specimens  left  in  a  bottle  were 
kept  alive  for  four  years  simply  by  adding  a  little  water  from 
time  to  time  to  make  up  for  evaporation.     Mr.  D.  Bryce  asked 
if  it  was  known  how  they  are  conveyed  from  place  to  place,  and 


544  PROCEEDINGS    OF    THE 

also  how  they  were  able  to  resist  the  effects  of  evaporation. 
Mr.  Scourfield,  in  replying,  instanced  that  the  eggs  of  such 
minute  creatures,  and  also  adults,  can  become  embedded  and  dry, 
and  remain  for  a  long  period  in  a  condition  of  suspended  anima- 
tion. Also,  that  one  species  of  Cyclops  and  Canthocampus  form 
a  kind  of  cocoon.  As  to  their  distribution  he  could  give  no 
information. 

Amongst  other  interesting  exhibits  was  a  specimen  of  Stephano- 
ceros  Eichornii — a  wonderful  example  of  the  art  of  mounting,  by 
Mr.  C.  F.  Rousselet,  Curator  R.M.S. 


At  the  503rd  Ordinary  Meeting  of  the  Club,  held  on 
December  22nd,  the  Vice-President,  Prof.  E.  A.  Minchin,  M.A., 
F.R.S.,  in  the  chair,  the  minutes  of  the  meeting  held  on 
November  24th  were  read  and  confirmed. 

Mr.  Frederick  Knott  was  balloted  for  and  duly  elected  a 
member  of  the  Club. 

A  vote  of  thanks  was  returned  to  Mr.  C.  F.  Rousselet,  Curator 
R.M.S.,  for  a  valuable  donation  to  the  Cabinet  of  twenty-four 
slides  of  Rotifera. 

Mr.  J.  Grundy  read  a  communication  from  Mr.  E.  M.  Nelson 
of  great  interest  to  metallurgists.  A  slide  was  exhibited  con- 
sisting of  a  thin  aluminium  disc  of  about  1  mm.  in  diameter,  such 
as  Mr.  Morland  uses  when  mounting  selected  diatoms,  mounted 
by  itself.  When  placed  under  a  |-in.  or  ^-in.  objective,  and 
illuminated  by  one  of  the  universal  condensers,  lamp  and  bull's- 
eye,  a  strong  top- illumination  is  obtained  by  reflex  light  from  the 
front  lens.  Mr.  Nelson  states  that  this  idea  may  prove  useful 
for  the  examination  of  metals,  as,  instead  of  using  a  cubic  |  in. 
for  examination,  if  the  end  of  a  wire,  say,  1*5  mm.  thick  and 
2  mm.  long,  was  polished  and  fastened  on  a  slip,  the  metal  might 
be  investigated  probably  quite  as  well  as  with  a  larger  piece. 
He  further  stated  that  this  idea  was  by  no  means  new,  as  it  was 
first  expounded  by  Rainey  sixty  years  ago,  and  later  by  Prof. 
B.  T.  Lowne  about  1888,  and  again  more  recently  by  J.  W. 
Gordon  at  the  R.M.S. 

To  those  interested,  the  valuable  description  by  Prof.  Lowne  on 
top-lighting  by  reflections  from  the  front  and  back  of  the  front 
lens  of  the  objective  will  be  found  on  p.  371,  vol.  iii.,  second 


QUEKETT    MICROSCOPICAL    CLUB.  545 

series  of  the  Journ.  Q.  M.  C.  Mr.  Grundy  exhibited  a  slide  of 
mounted  copper  which  illustrated  the  same  lighting. 

Mr.  J.  Wilson  read  some  notes  by  Mr.  H.  Whitehead,  B.Sc., 
F.R.M.S.,  on  an  epizoic  infusorian,  Trichodina  Steinii  C.  and  L., 
found  on  Turbellaria.  These  were  found  on  a  specimen  of 
Mesastoma  tetragonum,  moving  about  over  the  surface  of  the 
body  and  between  the  folds.  They  are  a  species  closely  allied  to 
Trichodina  pediculus,  which  is  frequently  found  on  Hydra,  but 
differs  in  that  T.  pediculus  has  an  inner  as  well  as  an  outer  ring 
of  teeth.  The  body  of  T.  Steinii  varies  considerably  in  shape; 
but  when  at  rest  it  is  cylindrical,  the  diameter  at  the  base  being 
equal  to  the  height  (about  40  /a.),  the  basal  circle  of  cilia  being  in 
contact  with  the  body  of  the  Turbellarian,  while  the  adoral  cilia 
form  a  spiral  leading  to  the  mouth.  When  free-swimming,  the 
adoral  cilia  are  retracted,  while  the  basal  circlet  is  used  for 
the  purpose  of  locomotion.  The  protoplasm  contains  a  number 
of  small  spherular  structures,  and  one  or  two  contractile  vacuoles 
are  to  be  seen.  It  possesses  a  large  horseshoe-shaped  nucleus, 
which  can  only  be  seen  in  stained  specimens.  Mr.  Whitehead 
pointed  out  an  important  discrepancy  which  appears  between 
Saville  Kent's  description  (probably  taken  from  Claparede  and 
Lachmann)  and  his  own  observations.  Saville  Kent  stated  that 
the  posterior  horny  ring  was  continuous  and  denticulate  only  on 
its  outer  edge.  A  careful  examination  of  the  adherent  organ 
shows  it  to  consist  of  an  outer  circle  of  cilia,  and  within  this 
a  circle  composed  of  about  eighteen  or  twenty  separate  chitinous 
teeth,  with  the  points  directed  obliquely  outwards.  Vejdovsky, 
in  1881,  published  a  detailed  account  of  the  species,  and  stated 
that  he  had  found  T.  Steinii  on  Planaria  gonocephala.  As  far  as 
can  be  seen,  the  host  suffers  no  inconvenience  from  the  trichodina, 
and  there  is  no  evidence  of  parasitism  ;  consequently  the  non- 
committal term  "  epizoic  "  is  more  satisfactory  than  "  parasitic  " 
in  this  case. 

A  discussion  followed,  during  which  Mr.  Rousselet  said  he 
remembered,  many  years  ago,  finding  a  T.  Steinii  on  a  rotifer. 

In  reply  to  a  question  by  Mr.  Scourfield  about  the  formation 
of  chitinous  teeth,  the  chairman  stated  that  some  stalked, 
non -contractile  forms  of  Vorticella  fasten  themselves  down  by 
means  of  a  kind  of  glue  exuded  by  the  cilia,  which  hardens. 
Probably  these  teeth  are  an  adaptation  of  similar  development. 


546  PROCEEDINGS    OF    THE 

This   interesting   contribution    was    illustrated    by   a    series   of 
drawings  on  the  blackboard. 

Mr.  J.  Burton  read  a  communication  from  Mr.  E.  M.  Nelson 
on  "  Palaeozoic  Fungi."  His  object  in  bringing  this  subject 
forward  was  to  indicate  to  the  members  the  extreme  interest 
contained  in  the  study  of  the  flora  of  palaeozoic  days,  and  in  the 
hope  that  some  may  take  up  this  fascinating  branch  of  science. 
Many  microscopists  are  aware  of  a  disease  called  "  diatom-fever  "  ; 
but  Mr.  Nelson  can  state  that  "  palaeo-botany  fever  "  produced 
a  much  higher  temperature,  and  he  hoped  it  would  prove  very 
contagious  amongst  the  members.  Every  one  is  aware  that 
botanical  fossils  have  been  studied  for  many  years ;  but  it  is 
only  during  the  last  twenty  or  thirty  years  that  material  suitable 
for  microscopical  examination  has  been  available.  The  so-called 
fossils  from  coal-mines  in  museums  are  not  really  fossils,  but 
casts,  the  plants  having  become  carbonised,  and  their  cellular 
structure  can  no  longer  be  seen.  A  piece  of  coal  under  micro- 
scopic examination  would  reveal  no  structural  cell-work,  for  that 
has  been  changed  long  ago.  In  recent  years  some  true  fossil 
plants  have  been  found  so  perfect  that  sections  show  the  delicate 
cell  structure  almost  as  clearly  as  freshly  cut  and  stained  sections 
of  present-day  specimens.  As  an  example  of  the  knowledge 
obtained  by  the  direct  application  of  the  microscope  in  such 
cases,  Mr.  Nelson  takes  the  fact  that  coal  was  formerly  con- 
sidered to  be  chiefly  formed  from  ferns,  whereas  now  it  is  known 
that  ferns  were  by  no  means  plentiful  in  those  days,  and  that  the 
bulk  of  coal  was  formed  by  other  forms  of  plants.  These  other 
plants  had  fernlike  vegetative  characters,  leaves,  etc.,  but  their 
method  of  reproduction  differed  entirely  from  that  of  ferns.  He 
instanced  how  perfectly  the  vegetable  tissues  are  preserved  by  a 
slide  in  his  collection  containing  a  section  of  a  small  seed,  with 
the  pollen  grains  in  the  pollen  chamber,  just  previous  to  fertilisa- 
tion, although  50,000,000  years  must  have  elapsed  since  they 
entered.  The  tracheides  and  the  bordered  pits  in  the  cells  are 
also  well  preserved.  He  recommends  those  wishing  to  take  up 
this  subject  to  read  Dr.  D.  H.  Scott's  charming  book,  Studies 
in  Fossil  Botany  (2  vols.,  Black),  or  Ancient  Plants,  by  Miss 
Stopes,  D.Sc.  (Blackie).  With  reference  to  a  slide  exhibited, 
a  section  of  a  leaf  from  Lepidodendron  Harcourtii — one  of  the 
best  known  fossil  stems,  upon  which  was  to  be  observed  a  brown 


QUEKETT    MICROSCOPICAL    CLUB.  547 

oval  ball,  and  quite  a  common  object  in  many  of  these  sections 
— a  power  of  200  showed  that  it  is  formed  in  part  by  little  rods, 
somewhat  interlaced,  not  unlike  the  house  of  the  caddis-worm. 
They  are  found  singly,  but  more  often  in  groups,  especially 
in  those  parts  of  leaves  where  the  cellular  tissue  has  been  dis- 
integrated. Mr.  Nelson  considers  that  they  are  correlated  with 
this  disintegration,  and  possibly  are  some  sort  of  fungus  spores 
(gonidia).  It  is  needless  to  say  that  no  mycelium  has  been 
observed,  so  that  it  is  not  possible  to  tell  whether  the  invasion 
of  the  fungus  took  place  while  the  leaf  was  living  on  the  tree  or 
after  it  had  fallen. 

The  reading  of  this  paper  caused  considerable  discussion. 

Prof.  Minchin  said  he  remembered  Prof.  Oliver  stating  that  he 
had  found  cells  in  coal  showing  a  nucleus. 

Mr.  N.  E.  Brown  then  stated  that  the  brown  balls  shown  on 
the  slide  were  certainly  not  fungus  spores,  but  were  more  likely 
to  be  of  animal  origin.     Mr.  J.  Wilson  concurred. 

Mr.  R.  Paulson,  F.L.S.,  pointed  out  that  if  they  were  gonidia 
they  should  be  on  the  surface  of  the  leaf.  He  was  interested  in 
the  subject,  as  he  had  been  trying  to  find  out  how  far  back 
lichens  are  to  be  found,  and  had  never  found  traces  of  even  the 
lower  forms  as  fossils. 

Mr.  J.  Grundy  referred  to  an  address  given  to  the  Club  by 
Prof.  W.  C.  Williamson  (Professor  of  Botany,  Owens  College, 
Manchester)  on  "  The  Mineralisation  of  the  Minute  Tissues 
of  Animals  and  Plants"  (Joum.  Q.  M.  C,  Ser.  2,  Vol.  V.  p.  186), 
which  holds  very  material  information  for  all  inclined  to  learn 
more  of  the  subject  as  to  what  a  fossil  is  and  how  formed. 

Amongst  other  exhibits,  Mr.  G.  K.  Dunstall,  F.R.M.S.,  showed 
a  living  specimen  of  the  rotifer  Callidina  bilfingeri,  which  has 
only  been  seen  twice  previously  in  England. 


At  the  504th  Ordinary  Meeting  of  the  Club,  held  on  January 
26th,  1915,  the  President,  Prof.  Arthur  Dendy,  D.Sc,  F.R.S.,  in 
the  chair,  the  minutes  of  the  meeting  held  on  December  22nd, 
1914,  were  read  and  confirmed. 

Messrs.  David  Griffiths,  J.  Grant  Andrews  and  Arthur  Boltz 
were  balloted  for  and  duly  elected  members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks  of 
the  members  voted  to  the  donors. 


548  PROCEEDINGS    OF   THE 

The  Hon.  Secretary  said  that  as  the  next  meeting  would 
be  their  Annual  Meeting,  at  which  the  officers  and  members 
to  fill  vacancies  on  the  committee  would  have  to  be  elected, 
nominations  must  be  made  on  this  occasion.  The  list  of  officers 
nominated  by  the  committee  was  then  read,  and  names  for  the 
committee  were  proposed  and  seconded  by  the  members  An 
auditor,  on  behalf  of  members,  was  elected. 

At  the  request  of  the  chairman,  Vice-President  Prof.  E.  A. 
Minchin,  M.A.,  F.R.S.,  read  a  paper  giving  "Some  Details  in 
the  Anatomy  of  the  Rat  Flea,  Geratophyllus  fasciatus" 

The  paper  was  illustrated  by  lantern  diagrams  projected  on  to 
the  screen.  A  number  of  micro-preparations  made  by  Prof. 
Minchin,  illustrating  the  various  points  of  structure  described, 
were  exhibited  under  microscopes.  These  Prof.. Minchin  kindly 
presented  to  the  Club 

The  President  said  he  was  sure  they  had  all  been  delighted 
with  Prof.  Minchin's  description  of  the  minute  anatomy  of  the 
rat  flea.  The  main  object  of  the  researches  was  to  trace  the 
development  of  the  trypanosome  found  in  the  rat  flea ;  but  they 
had  had  a  full  account  of  the  flea,  as  a  type  of  a  class  of  insects 
which  exhibited  a  high  development  of  organisation.  He  asked 
the  members  to  pass  a  very  hearty  vote  of  thanks  to  Prof. 
Minchin  for  the  treat  he  had  given  them,  for  the  trouble  he  had 
taken  in  bringing  to  the  meeting  so  many  specimens,  and  for  his 
kindness  in  presenting  the  very  beautiful  preparations  to  the 
Club's  Cabinet.     This  was  assented  to  by  acclamation. 


At  the  505th  Ordinary  (which  was  also  the  49th  Annual) 
Meeting  of  the  Club,  held  on  February  23rd,  the  President, 
Prof.  Arthur  Dendy,  M.A.,  F.R.S.,  in  the  chair,  the  minutes 
of  the  meeting  held  on  January  26th  were  read  and  confirmed. 

Messrs.  Mark  T.  Denne,  Charles  H.  A.  Brooke,  W.  Powell 
Sollis  and  R.  E.  Handford  were  balloted  for  and  duly  elected 
members  of  the  Club. 

The  list  of  donations  to  the  Club  was  read,  and  the  thanks 
of  the  members  voted  to  the  donors. 

The  President  informed  those  present  that  news  of  the 
death  of  Mr.  F.  W.  Millett,  F.R.M.S.,  had  been  received.  He 
was  one    of   the   oldest    members,  having    joined    the    Club    at 


QUEKETT    MICROSCOPICAL    CLUB.  549 

its  foundation  in  July  1865.  He  was  eight}7-t\vo  at  the  time 
of  his  death  on  February  8th,  and  had  not  been  able  to  attend 
the  meetings  for  a  number  of  years.  He  was  an  authority  on 
the  Foraminifera. 

The  President  asked  Mr.  Scourfield  and  Mr.  Hilton  to  act  as 
scrutineers  of  the  ballot  for  officers  and  council  of  the  Club  for 
the  ensuing  year.  He  wished  to  mention  that  any  member 
could  erase  the  name  of  any  of  the  officers,  if  he  thought  proper, 
and  substitute  the  name  of  any  other  person  in  the  space  pro- 
vided on  the  ballot  paper  for  that  purpose.  Five  members  of 
committee  would  have  to  be  elected  in  place  of  four  who  retired 
by  rotation  and  of  Mr.  Heron-Allen,  who  had  resigned.  Six 
members  were  nominated  at  the  last  meeting,  but  since  then 
Mr.  Lionel  C.  Bennett  had  withdrawn  his  name,  so  that  the 
number  remaining  would  fill  the  vacancies. 

The  Hon.  Secretary  read  the  committee's  report,  which  detailed 
a  satisfactory  year's  work,  though  the  war  had  somewhat  inter- 
fered with  the  personnel  of  the  Club. 

The  Hon.  Treasurer  read  the  balance  sheet,  which  disclosed 
a  thoroughly  sound  financial  condition. 

The  adoption  of  the  report  and  balance  sheet  having  been 
moved  and  seconded,  was  put  to  the  meeting  by  the  President, 
and  unanimously  carried. 

The  President  then  asked  Prof.  Minchin  to  take  the  chair, 
and  proceeded  to  give  his  annual  address.  The  title  was  "  The 
Biological  Conception  of  Individuality." 

At  the  conclusion  Prof.  Minchin  said  they  had  just  listened 
to  a  most  interesting  and  instructive  address — one  which  they 
would  be  glad  to  think  over  and  to  read  in  their  Journal,  if 
Prof.  Dendy  would  kindly  allow  them  to  print  it.  He  moved 
that  "  The  hearty  thanks  of  the  meeting  be  given  to  the  Presi- 
dent for  his  address,  and  that  he  be  asked  to  allow  it  to  be 
printed  in  the  Journal." 

The  motion  was  carried  by  acclamation. 

Prof.  Dendy,  in  reply,  thanked  those  present  for  the  attention 
paid  to  his  remarks,  and  said  he  should  be  extremely  pleased  to 
place  the  address  at  their  disposal  for  publication. 

A  vote  of  thanks  to  the  scrutineers  and  auditors  was  proposed 
and  carried. 

A  vote  of  thanks  to  the  officers  and   committee  was  proposed 


550        PROCEEDINGS    OF   THE    QUEKETT    MICROSCOPICAL    CLUB. 


by  Mr.  Capell,  F.R.M.S.  He  did  not  think  this  should  be  done 
as  a  mere  matter  of  form.  The  members  came  to  the  meetings 
and  found  things  went  along  smoothly,  and  the  work  was  done 
for  them  efficiently  and  with  willingness  and  cheerfulness,  and 
they  all  gained  by  the  efforts  of  those  who  carried  it  on. 

The  proposal  was  seconded  by  Mr.  Gammon,  and  carried. 

The  Hon.  Treasurer  (Mr.  F.  J.  Perks)  acknowledged  the  vote. 
He  said  there  was  a  considerable  amount  of  work  done  by  the 
officers  apart  from  that  which  was  apparent  at  the  meetings. 
He  thanked  them  for  their  kind  expressions,  and  could  promise 
they  would  in  the  future,  as  in  the  past,  do  their  best  for  the 
prosperity  of  the  Club. 

The  scrutineers  having  handed  in  their  report,  the  following 
gentlemen  were  declared  duly  elected  as — 


President 


Four  Vice-Presidents 


Hon.  Treasurer 
Secretary 

A  ssistant  Secretary 
Foi*eign  Secretary  . 
Reporter  .... 
Librarian  .  .  . 
Curator  .... 
Editor     .... 


Members  of 
Committee. 


Prof.  Arthur  Dendy,  D.Sc,  F.R.S. 
[G.  F.  Rousselet,  F.R.M.S. 

E.  J.     Spitta,    L.R.C.P.,    M.R.C.S., 
F.R.M.S. 

D.  J.  Scourfield,  F.Z.S.,  F.R.M.S. 
IProf.  E.  A.  Minchin,  M.A.,  F.R.S 
Frederick  j.  Perks. 
James  Burton. 

F.  E.  Robotham. 

C.  F.  Rousselet,  F.R.M.S. 

R.  T.  Lewis,  F.R.M.S. 

S.  C.  Akehurst,  F.R.M.S. 

C.  J.  Sidwell,  F.R.M.S. 

A.  W.  Sheppard,  F.Z.S.,  F.R.M.S. 
fj.  M.  Offord,  F.R.M.S. 

Charles  S.  Todd. 

N.  E.  Brown,  A.L.S. 

Ed.  E.  Banham. 
IC  H.  Bestow,  F.R.M.S. 


551 


FORTY-NINTH   ANNUAL   REPORT. 

Your  Committee  in  presenting  their  Report  for  the  year  ending 
December  1914  will  scarcely  need  to  remind  members  that  for 
almost  half  the  time  covered  by  it,  namely  the  last  five  months, 
conditions  have  been  of  an  altogether  abnormal  and  unpropitious 
character.  Taking  this  into  account,  it  is  satisfactory  to  find 
that  the  number  of  members  elected  has  been  forty-one ;  this  is 
slightly  above  the  average  of  the  previous  six  years.  The  resig- 
nations have  been  twenty-five,  which  is  more  than  usual,  and 
was  largely  due  to  enlistment  and  other  circumstances  connected 
with  the  war.  The  deaths  have  been  nine,  again  somewhat  more 
than  the  average,  removing  some  of  our  older  and  more  noted 
members;  leaving  the  present  membership  447. 

Dr.  Arthur  Mead  Edwards  of  New  Jersey,  U.S.A.,  the  oldest 
honorary  member,  elected  in  January  1868,  died  in  September. 
Ln  November  we  had  to  regret  the  loss  of  Dr.  M.  C.  Cooke.  He 
has  been  not  inappropriately  called  the  "  Father  of  the  Club  " ; 
he  was  not  only  one  of  its  founders,  but  his  writings  and  general 
work  must  have  done  an  incalculable  amount  to  disseminate  a 
popular  interest  in,  and  knowledge  of,  microscopy.  Although  he 
was  in  his  ninetieth  year  at  the  time  of  his  death  he  had  shortly 
before,  on  the  celebration  of  our  five  hundredth  meeting,  been 
able  to  write,  with  his  own  hand,  a  letter  expressing  his  pleasure 
at  the  prosperity  of  the  Club,  and  his  wishes  for  its  continuance. 
An  obituary  notice  appeared  in  the  November  number  of  the 
Journal. 

Among  the  losses  sustained  owing  to  the  war,  it  should  be 
recorded  that  Mr.  Pledge,  Assistant  Secretary  for  nine  years,  has 
been  compelled  to  resign  his  office  in  consequence  of  having  to 
place  himself  at  the  disposal  of  the  military  authorities ;  and  we, 
therefore,  no  longer  have  the  advantage  of  his  very  excellent 
reports  of  our  meetings  in  the  English  Mechanic  and  elsewhere, 
for  which  it  has  been  the  pleasing  duty  of  the  Committee  so  often 
to  express  their  thanks  to  him.  The  Club  is  to  be  congratulated 
on  the  fact  that  Mr.  Robotham  kindly  consented  to  fill  the  vacant 


552  FORTY-NINTH    ANNUAL    REPORT. 

position,  and  for  some  months  has  earned  the  thanks  of  all  by 
his  efficiency  in  performing  the  duties  connected  with  it. 

The  number  present  at  both  the  Ordinary  and  Gossip  Meetings 
has  been  good,  though  for  the  latter  part  of  the  time  it  has  been 
lessened  somewhat  by  the  absence  of  previously  regular  attendants 
owing  to  engagements  in  various  capacities  in  the  army,  as  well 
as  by  the  general  unrest  brought  about  by  the  war.  On  the 
Gossip  nights  there  has  been  no  less  enthusiasm  and  good  work 
done  than  previously ;  but  the  Committee  wish,  while  thanking 
those  who  have  done  so  much  to  make  these  meetings  a  success, 
to  press  upon  the  attention  of  all,  the  desirability  of  their  making 
an  effort  to  bring  a  microscope  and  some  object  for  exhibition, 
and  thus  add  their  endeavours  for  the  well-being  of  the  whole. 

The  papers  and  notes  read  were  as  follows  : 

Communications  during  1914. 

January  27th. — Some  Observations  on  Sub-stage  Illumination, 

by  S.  C.  Akehurst. 
January  27th. — On  an  Attempt  to  Resolve  Pinnularia  nobilis, 

by  T.  A.  O'Donohoe. 
February  2ith. — President's   Address  :    Organisms   and    Origins, 

by  Prof.  Arthur  Dendy,  D.Sc.,  F.R.S. 
March  2kth. — Some  Notes  on  the  Structure  of  Diatoms,  by  N.  E. 

Brown,  A.L.S. 
March  2kth. — On  a  New  Oil-Immersion  Objective  and  On  a  New 

Method  of  Illumination,  by  E.  M.  Nelson,  F.R.M.S. 
April  2&th. — On  a  New  Low-power  Condenser,  by  E.  M.  Nelson, 

F.R.M.S. 
April   2&th. — On   the    Fertilisation    of    Vinca   minor,    by  N.    E. 

Brown,  A.L.S. 
May  26th. — Notes  on  the  Cultivation  of  Badhamia  utricular  is, 

by  A.  E.  Hilton. 
May  26th.— On  Binocular  Microscopes,  by  E.  M.  Nelson,  F.R.M.S. 
June  23rd. — Notes  on  Fossils  from  the  Coal  Measures,  by  W.  E. 

Watson  Baker. 
June  23rd. — Notes  on  the  History  of  tjie  Club,  in  Celebration  of 

the  500th  Ordinary  Meeting,  by  Dr.  E.  J.  Spitta. 
October   27th. — Report   of   the    Havre    Meeting   of   the    British 

Association,    by    C.    F.     Rousselet,    F.R.M.S.,    the    Club's 

delegate. 


FORTY-NINTH    ANNUAL    REPORT.  553 

October  21th. — On  the  Minimum  Visible,  by  A.  A.  C.  Eliot  Merlin. 

October  27th. — Remarks  on  two  Species  of  African  Vol  vox,  by 
C.  F.  Rousselet,  F.R.M.S. 

November  24th. — A  New  Copepod  found  in  Water  in  the  Hollows 
on  Tree  Trunks  in  Epping  Forest,  by  D.  J.  Scourfield,  F.Z.S. 

December  22nd. — On  an  Epizoic  Infusorian — Trichodina,  found 
on  the  Planarian  Mesostoma  tetragonum,  by  Mr.  White- 
head, B.Sc. 

December  22nd. — Palaeozoic  Fund,  bv  E.  M.  Nelson,  F.R.M.S. 

Your  Committee  thanks  the  authors  of  these  valuable  com- 
munications on  behalf  of  the  members.  It  may  be  observed  that 
short  notes  are  more  frequent  than  usual,  and  it  is  desired  to 
express  the  appreciation  in  which  this  class  of  communication 
is  held ;  those  who  are  not  able  to  undertake  a  lengthy  and 
scientific  paper  may  still  be  able  to  add  their  quota  to  the  work  of 
the  Club  by  giving  short  accounts  of  their  finds,  and  of  the 
methods  and  experiences  of  their  investigations. 

Several  new  and  useful  pieces  of  apparatus — often  the  inven- 
tion of  our  own  members — have  been  exhibited  and  described. 
Notice  of  these  will  be  found  in  the  reports  of  the  meetings 
in  the  Journal. 

The  veteran  microscopist,  Mr.  E.  M.  Nelson,  as  in  former  years, 
has  laid  the  Club  under  an  obligation  by  his  numerous  and  inter- 
esting communications.  In  May  he  gave  a  paper  on  "  Binocular 
Microscopes,"  very  fully  treating  the  subject  of  the  new  high- 
power  binoculars.  At  the  same  meeting  Messrs.  Beck  and 
Messrs.  Leitz  exhibited  samples  of  this  class  of  instrument,  thus 
giving  an  opportunity  of  judging  their  capabilities,  and  greatly 
adding  to  the  interest  of  the  proceedings.  In  November  Mr. 
Scourfield  read  a  paper  describing  a  new  species  of  Copepod  he 
had  found  in  Epping  Forest.  The  discovery  by  Mr.  Rousselet  of 
the  sexual  forms  of  two  species  of  African  volvox,  among  speci- 
mens he  had  received  from  Dr.  Jakubski  of  Lemberg,  is  note- 
worthy. The  account  of  the  experiences  of  Mr.  Rousselet  as 
delegate  to  the  Havre  meeting  of  the  Corresponding  Societies  of 
the  British  Association  on  the  eve  of  the  outbreak  of  war  is  given 
in  the  Journal. 

In  February  a  Conversazione  was  held  at  King's  College  :  this 
was  much  appreciated  by  members  and  their  friends.      It  was  the 
Journ.  Q.  M.  C,  Series  II.— No.  76.  38 


554  FORTY-NINTH    ANNUAL    REPORT. 

first  that  the  Club  had  held  for  seventeen  years,  and  the  hope 
was  freely  expressed  that  so  long  a  time  would  not  be  allowed  to 
elapse  before  another  occurred. 

The  meeting  on  June  23rd  was  the  five  hundredth  Ordinary 
Meeting.  In  the  absence  of  the  President — who  had  just  left 
for  Australia  as  the  President  of  the  Zoological  section  of  the 
British  Association — the  chair  was  taken  by  Dr.  S  pitta,  who, 
in  celebration  of  the  occasion,  gave  the  meeting  a  more  social 
character  than  usual,  quite  in  accordance  with  the  older  tra- 
ditions of  the  Club. 

The  Librarian  reports  that,  notwithstanding  some  inconveni- 
ence being  felt  owing  to  the  restricted  space  at  his  disposal,  the 
average  number  of  books  borrowed  in  previous  years  has  been 
maintained.  The  Library  sub-committee  has  met  regularly  on 
the  first  and  third  Tuesdays  in  the  month,  and  members  will  be 
glad  to  hear  that,  after  considerable  but  unavoidable  delay,  the 
Catalogue  of  Books  is  in  the  hands  of  the  printers.  This,  com- 
bined with  the  appointment  of  Mr.  Todd  as  Assistant  Librarian, 
will  render  the  work  of  the  department  more  expeditious,  and  it 
is  hoped  that  advantage  will  be  taken  of  the  increased  facilities. 
The  best  thanks  of  the  Club  are  due  to  Mr.  Todd,  to  Mr.  Shep- 
pard  and  to  Mr.  Bennett,  for  the  interest  and  energy  they  have 
exercised  in  carrying  out  the  by  no  means  light  task  of  re- 
organising the  Library. 

List  of  Books  Purchased  and  Presented  since  October  29th, 

1914,  to  January  1915. 

Memoirs  of  Indian  Museum.  Vol.  III.  4.  Oriental  Passalidae 
(Coleoptera).     F.  H.  Graveley,  M.Sc. 

Presented  by  W.  Harold  S.  Cheavin. 

Water  Beetle  (JJytiscus  marginalis),  Common  Gnat  (Culex 
pipiens). 

Reports  on  Hydroida  collected  in  the  Great  Australian 
Bight  and  other  Localities.  Parts  II.  and  III.  W.  M. 
Bale,  F.R.M.S. 

Purchased. 
►Some  Minute  Animal  Parasites.     Fantham  and  Porter. 


FORTY-NINTH    ANNUAL    REPORT.  555 

Missouri   Botanic  Garden. 

Philippine  Journal  of  Science. 

Bergen   Museum. 

United  States  National  Herbarium. 

Royal  Society.     B  Series. 

Natural   History  Society  of  Glasgow. 

Zoologisch-botanischen    Gessellschaft    Wien.      LXIV.      Parts   1-4. 

1914. 
United  States  National  Museum. 
Nuova  Notarisia. 
Liverpool  Microscopical  Society. 
Royal  Dublin  Society. 
University  of  California. 

Illinois  State  Laboratory  of  Natural  History. 
Societe  Roy  ale  de  Botanique  de  Belgique.     Tome  LIL     Series  II. 

March   1914. 
Brighton  and  Hove  Natural  History  and  Philosophical  Society. 
Edinburgh  Royal  Botanic  Garden 

Northumberland  and  Durham  Natural  History  Society. 
Torquay  Natural  History  Society. 
Photographic  Journal. 

During    the    year    ending    December    1914    the    Library    has 
received  the  following  publications  : 

Quarterly  Journal  of  Microscopical  Science. 

Victorian  Naturalist. 

Mikrokosmos.     Up  to  Part  5.      1914-1915. 

Royal  Microscopical  Society. 

British  Association  Report. 

Royal  Institution  of  Great  Britain,  Proceedings  of. 

Geologists    Association. 

Manchester  Literary  and  Philosophical  Society. 

Hertfordshire  Natural  History  Society. 

Botanical  Society  of  Edinburgh. 

Tijdschrift. 

Nyt  Magazine. 

Manchester  Microscopical  Society. 

Birmingham  and  Midland  Institute. 

Glasgow  Naturalists'  Society. 


556  FORTY-NINTH    ANNUAL    REPORT. 

Croydon  Natural  History  Society. 

Indian  Museum.,  Calcutta. 

Royal  Society  of  N.S.W. 

American  Microscojncal  Society. 

Smithsonian  Institution. 

Academy  of  Natural  Science,  Philadelphia. 

Missouri  Botanic  Garden. 

Philippine  Journal  of  Science. 

Bergen  Museum. 

During  the  year  eleven  excursions  were  held,  at  which  the 
average  attendance  was  23,  against  20-8  for  last  year.  Notwith- 
standing the  inclement  weather  on  some  of  the  dates,  the  average 
attendance  for  the  year  is  a  record.  An  excursion  had  been 
arranged  for  August  8  to  Hampton  Court,  but  owing  to  the 
unfavourable  weather  and  the  excitement  caused  by  the  war,  it 
was  abandoned.  Arrangements  had  also  been  made  for  an 
excursion  to  the  East  London  Water  Works,  but  owing  to  the 
war,  the  authorities  cancelled  the  permission.  An  excursion 
instead  was  made  to  various  ponds  in  Epping  Forest,  which  was 
very  successful.  There  were  no  new  species  to  record,  but 
Lemna  minor  was  found  abundantly  in  flower  in  one  of  the  ponds 
in  Trent  Park.  The  thanks  of  the  Committee  are  due  to  His 
Grace  the  Duke  of  Northumberland  and  to  Sir  Philip  Sassoon 
for  the  permission  to  visit  their  private  grounds. 

The  Curator  reports  that  all  through  the  year  there  has  been 

a  steady  demand  for  the  slides  and  instruments  under  his  care, 

and  111    preparations  have  been  added  to  the  Cabinets.     The 

principal   addition  has  been    the   purchase  of    47    fine   slides  of 

selected  Diatoms  mounted  in  styrax,  thus  bringing  up  the  Club's 

collections   of    Diatomaceae   to    1,550    preparations.     For   some 

time  past  Mr.  Rousselet  has  been  engaged  in  the  onerous  task  of 

overhauling,  and  in  many  cases  remounting,  the  type-collection 

of    Rotifera    he    presented    to    the    Club    some    years    since,  to 

which    he   has  recently  made   a   further   donation   of    24  slides, 

thus   increasing   the    total    to    over    260    species.     The    cordial 

thanks  of  the  Club  are  due  to  Mr.  Rousselet  for  his  labours,  and 

the  Club  is  to  be  congratulated  on  possessing  what  is  believed  to 

be  the  most  complete  type- collection  of   Rotifera  in  the  worldj 

with  the  exception  of  Mr.  Rousselet's  private  collection.     Up  to 


FORTY-NINTH    ANNUAL    REPORT.  557 

the  present  these  slides  have  only  been  available  for  reference  at 
the  rooms  ;  but  after  careful  consideration  the  Committee  has 
decided  to  lend  out  the  preparations,  under  certain  conditions,  to 
members  specially  interested  in  the  group.  The  Committee  has 
felt  it  necessary  to  make  some  restriction,  owing  to  the  delicate 
nature  of  the  slides,  and  the  difficulty  of  replacing  many  of  the 
rarer  species  in  the  event  of  accidental  damage,  as  any  such  loss 
would  considerably  detract  from  the  value  of  the  preparations  as 
a  type-collection.  The  demand  for  slides  is  generally  from  the 
newer  members,  and  the  Committee  regrets  that  greater  use  is 
not  made  of  the  Cabinets  by  the  older  members  and  those  who 
are  specialising,  as  the  Cabinets  contain  many  preparations  which 
could  not  fail  to  be  of  use  and  interest  to  them.  The  Curator 
will  be  pleased  to  render  any  assistance  and  information  in  this 
respect. 

The  Committee  again  begs  to  tender  its  best  thanks  to 
Mr.  Bestow  for  kind  assistance  rendered  to  the  Curator  in  the 
issue  of  slides. 

Thanks  are  due  to  the  Editors  of  the  English  Mechanic  and  of 
Knowledge  for  their  kindness  in  publishing  reports  of  the 
Meetings. 

Your  Committee  desires  to  thank  the  various  Officers  for  the 
unabated  energy  they  have  displayed  in  carrying  on  the  work  of 
the  Club,  work  which  they  are  conscious  not  seldom  entails  a 
considerable  amount  of  self-denial,  but  the  reward  for  which  is 
the  continued  prosperity  and  usefulness  of  the  Club,  founded  now 
nearly  half  a  century  ago. 


558 


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559 


OBITUARY  NOTICE. 

FORTESCUE  WILLIAM  MILLETT,  F.G.S.,  F.R.M.S. 

Born  November  Sth,  1833;  died  February  Sth,  1915. 

It  is  with  feelings  of  great  regret  we  have  to  record  the  death, 
in  his  eighty-second  year,  of  Mr.  F.  W.  Millett,  which  took  place 
on  February  Sth  at  his  residence  in  Brixham,  Devon. 

Mr.  Millett  was  a  native  of  Marazion,  in  Cornwall,  and  when 
about  twenty  years  of  age  came  to  reside  in  London.  From 
an  early  age  he  was  of  a  studious  nature,  and  his  connection 
with  the  Quekett  Microscopical  Club — he  joined  at  its  foundation 
in  July  1865 — fostered  an  early  taste  for  microscopical  work. 
He  was  elected  F.R.M.S.  in  1880,  and  in  1883  left  London 
to  reside  in  Cornwall.  From  about  that  date  the  study  of  the 
Foraminifera  became  his  principal  life-work. 

His    first    paper,  "The  Foraminifera  of  Gal  way,"  written  in 
collaboration  with  F.  P.  Balkwill,  was  published  in  the  Journal  of 
Microscopy   and  Natural  Science  in   1884.     It   was  a  paper  of 
considerable  zoological  importance,   but  the  lithographed  plates 
were  very  poor,  and  it  is  not  surprising  that  Millett  later  revised 
the  paper  and  issued  it  in   1908  as  a  private  reprint  with  half- 
tone reproductions  of  the  original  excellent  drawings.      Between 
1885  and  1902  Millett  published  a  series  of  short  papers  on  the 
Foraminifera  of  the  Pliocene  Beds  of  St.  Erth,  Cornwall,  which 
obtained  for  their  author  recognition  from  the  Royal  Geological 
Society  of  Cornwall   in   the  form  of    the  William    Bolitho  gold 
medal.     But    his    future    reputation    will    rest    principally    and 
securely  on  his  "  Report  on  the  Recent  Foraminifera  of  the  Malay 
Archipelago,"    which    appeared    in    the    Journal    of   the    Royal 
Microscopical    Society   at    intervals    between    1898-1904.      This 
monograph,  illustrated  profusely  by  the  author,  dealt  with  a  new 
zoological    area    and    contained    descriptions   of  many  new  and 
interesting  forms.     But  its  chief  value  to  the  student  lies  in  the 
careful  research  work  embodied   in  the  author's  bibliographical 
references  to  the  numerous  species  which  he  recorded  from  the 
material  examined.     This  was  unquestionably  Millett's  strongest 


560  OBITUARY    NOTICE. 

point,  for  he  had  devoted  a  lifetime  to  the  collation  and 
assimilation  of  the  work  of  his  predecessors,  both  British  and 
foreign,  and  no  man  had  a  wider  knowledge  of  the  subject,  or 
was  more  ready  to  place  it  at  the  disposal  of  fellow-workers. 

With  the  death  of  F.  W.  Millett  parses  almost  the  last 
survivor  of  the  famous  band  of  systematists  who  have  made 
British  research  into  the  Foraminifera  famous  throughout  the 
world.  Started  by  Williamson  and  continued  by  the  famous 
collaborators  W.  K.  Parker,  Rupert  Jones  and  H.  B.  Brady, 
and  by  the  equally  distinguished  W.  B.  Carpenter,  their 
systematic  work  has  reduced  to  a  more  or  less  exact  if  artificial 
science  the  chaos  in  which  the  group  had  previously  existed. 
Millett  assisted  Brady  in  the  preparation  of  the  great 
"Challenger"  report  (1884),  to  what  extent  it  is  impossible  to 
say,  but  probably  he  was  largely  responsible  for  the  elaborate 
synonymies  which  render  that  report  so  valuable.  He  also 
collaborated  in  the  Monograph  of  the  Foraminifera  of  the  Crag, 
published  by  the  Palaeontographical  Society,  and  here  his 
systematic  work  is  more  easily  traced.  If  his  total  output  of 
publications  is  small  as  compared  with  other  workers  in  the 
group,  it  was  largely  due  to  the  painstaking  care  which  he 
lavished  on  his  work.  Few  rhizopodists  will  be  less  revised  by 
the  publications  of  their  successors  than  F.  W.  Millett,  and  after 
all  that  is  the  real  test  of  scientific  work. 


561 


AN   ADDITION   TO   THE   OBJECTIVE. 

By  M.  A.  Aixslie,  R.X.,  B.A.,  F.R.A.S. 

{Read  April  21th,   1915.) 
Figs.  1  and  2. 

Probably  there  are  few  microscopists  who  are  in  the  habit  of 
using  high-power  dry  objectives  who  would  not  agree  that  the 
Correct  adjustment  of  the  tube-length  to  suit  the  thickness  of 
the  cover-glass  is  with  such  lenses  of  great  importance  if  good 
definition  is  to  be  obtained.  Definition  of  a  sort  may,  it  is  true, 
be  got  with  incorrect  tube-length  ;  but  only  by  unduly  closing- 
down  the  iris  diaphragm  and  thus  reducing  the  illuminating 
cone,  or  otherwise  interfering  with  the  uniformly  illuminated  back 
lens  which  is  the  basis  and  starting-point  of  all  correct  microscopic 
vision.  In  the  present  paper  I  am  not  considering  inferior 
definition  got  in  this  way  ;  I  am  only  considering  the  question 
of  obtaining  really  sharp  definition,  with  a  cone  of  illumination 
which  utilises  at  least  two-thirds  of  the  aperture  of  the  objective ; 
and  this  is  what  I  mean  when  I  speak  of  "  good  ' '  definition ; 
and  such  is  only  to  be  obtained  by  careful  adjustment  of  the 
tube-length  to  suit  the  thickness  of  the  cover-glass. 

With  objectives  fitted  with  correction  collars  this  paper  has 
not  much  to  do  ;  the  correction  collar  to  a  large  extent  obviates 
the  change  of  tube-length  without  interfering  much  with  the 
magnifying  power,  and  is  useful  in  other  ways,  as  for  example 
in  focusing  through  the  various  planes  of  a  thick  object ;  but 
unfortunately  it  seems  to  be  going  out  of  use,  except  in  the  dry 
apochromats  and  in  water-immersions  ;  and  as  99  out  of  100  of 
the  high-power  dry  objectives  met  with  at  the  present  time 
are  without  this  appliance,  I  shall  not  take  it  into  further  con- 
sideration, but  confine  my  attention  to  the  objective  as  com- 
monly used. 

If  we  open  a  treatise  on  Microscopy,  we  are  pretty  sure  to 
find  the  question  of  cover-glass  and  tube-length  alluded  to  more 
or  less  (usually  less)  fully.     The  reader  is  told  that  for  a  thick 

Jourx.  Q.  M.  C,  Series  II.— No.  77. 


562        M.    A.    AINSLIE    ON    AX   ADDITION   TO    THE    OBJECTIVE. 

cover-glass  the  tube  is  to  be  shortened,  and  that  it  is  to  be 
lengthened  for  a  thin  ;  and  the  importance  of  the  matter  is 
impressed  on  the  reader,  even  to  the  extent  of  saying  that  "  the 
correction  of  the  objective  and  the  tube-length  ought  to  vary 
with  every  object"  (Dallinger),  a  statement  which  would  appear 
to  require  some  modification  in  the  case  of  oil -immersion  objec- 
tives. 

Little,  however,  is  usually  said  as  to  how  the  correct  tube- 
length  is  to  be  recognised  when  obtained,  and  nothing  as  to 
how  much  we  may  expect  to  have  to  move  the  draw-tube.  On 
this  latter  point  I  hope  to  give  some  data  which  may  prove 
useful. 

One  of  the  first  things  to  strike  any  one  who  tries  to  examine 
a  few  mounted  specimens,  with,  say  an  l/8th,  is  that  the  range 
of  draw-tube  of  the  modern  stand  is  often  insufficient  to  allow 
for  more  than  a  very  slight  variation  in  the  thickness  of  the 
cover-glass  ;  and  this  is  more  particularly  the  case  with  stands 
of  Continental  make,  in  which  the  available  range  is  often  not 
more  than  50  mm.  ;  and  to  give  some  idea  of  what  a  hindrance 
to  observation  this  may  prove,  I  may  say  that  with  an  English 
•stand  (by  Watson)  having  the  good  range  of  tube-length  of  92  mm. , 
-and  using  a  Leitz  No.  7  (which  is  a  1/8 tli  of  N.A.  0*85),  I  have 
found  it  impossible  to  examine  some  of  the  beautiful  slides  of 
Diatomaceae  in  the  Club  Cabinet,  in  some  cases  because  the 
cover-glasses  were  too  thin,  and  in  other  cases  because  they 
were  too  thick.  With  the  limited  range  of  the  Continental 
draw-tube  one  would,  of  course,  be  still  worse  off. 

Another  point  on  which  the  text-books  are  silent,  but  which 
soon  becomes  evident  to  any  one  who  has  occasion  to  use  objec- 
tives  of   different   powers,   is   that   the   change   of   tube-length 
necessary  to  correct  for  a  given  variation  in  the  thickness  of 
the  cover-glass  is  not  always  the  same  ;    it  varies  enormously 
with  the  power  of  the  objective,  and  also,  to  some  extent,  with 
the  formula  on  which  the  objective  is  constructed.     At  one  end 
of  the  scale  we  have  such  objectives  as  the  half-inch  "  Holos ' 
of  Watson  &  Son,  N.A.  0*65,  which  requires  a  change  in  the 
tube-length  of  about  1*2  mm.  only  to  compensate  for  a  variation 
of  0*01  mm.  in  the  thickness  of  the  cover-glass  ;    and  the  Zeiss 
12  mm.  Apochromat,  of  the  same  N.A.,  which  requires  a  change 
of  about  2  mm.  under  the  same  conditions. 


M.    A.    AIXSLIE    ON    AX    ADDITION    TO   THE    OBJECTIVE        563 

These  objectives  have,  in  fact,  the  extremely  useful  property 
of  working  through  almost  any  cover-glass  ;  even  through  a 
thin  slip,  if  the  tube-length  be  closed  down  sufficiently,  which 
in  the  case  of  these  objectives  is  almost  always  possible. 

As  we  increase  the  power  of  our  objectives,  the  alteration 
required  in  the  tube-length  increases  rapidly  ;  to  give  only  a 
few  instances,  the  figures  are  roughly  as  follow  for  certain 
typical  objectives  : 

Watson  6  mm.  Holos,  N.A.  0'84        .         .         .3*4 

Leitz  No.  5  (l/5th-in.) 7*5 

Watson  l/6th-in.,  N.A.  0'74  9D 

Zeiss  "  G  "  water-immersion      ....  9'5 

Zeiss  4-mm.  Apo.  (without  using  correction  collar)  13'0 

Leitz  No.  6  (l/6th-in.) 14-0 

Leitz  No.  7  (l/8th-in.) 20'0 

So  that  a  typical  l/8th-in.  is  ten  times  as  sensitive  in  this  respect 
as  the  Zeiss  12-mm.,  and  seventeen  times  as  sensitive  as  the 
Watson  1/2-in.  "  Holos." 

In  passing,  I  must  say  that  this  seems  to  me  to  be  a  strong- 
point  in  favour  of  the  employment  of  objectives  of  moderate 
power,  as  long  as  they  are  of  sufficient  excellence  to  stand  the 
high  eye-piecing  necessary  to  give  the  desired  magnification. 
The  difficulty  of  using  such  a  lens  as  the  Leitz  No.  7  with  a  range 
of  only  50  mm.  in  the  draw-tube  will  now  be  fairly  obvious. 

It  might  be  thought  that  a  good  deal  of  this  difference  between 
objectives  of  different  powers  is  due  to  the  N.A.  of  the  higher 
powers  being,  as  a  rule,  greater  than  that  of  the  lower  ;  but  the 
above  figures  are  practically  unaltered  when  the  N.A.  is  reduced  to 
about  0'6  in  each  case,  though  of  course  the  effect  of  incorrect 
tube-length  on  the  definition  is  not  so  marked  as  with  the  full 
aperture. 

Although  I  am  confining  my  attention  to  objectives  with 
N.A.  not  less  than  about  0'65,  it  must  not  be  thought  that  those 
of  lower  N.A.  are  altogether  insensitive  to  correct  tube-length  ; 
a  25-mm.  objective  of  N.A.  0"3,  for  example,  will  not  work 
really  well  at  any  but  its  computed  tube-length,  although  such 
objectives  are  not  very  sensitive  to  alterations  in  the  thickness 
of  the  cover-glass. 


564       M.    A.    AINSLIE    ON   AN    ADDITION    TO    THE    OBJECTIVE. 

I  now  come  to  the  device  which  I  am  bringing  to  your  notice 
for  overcoming  the  difficulty  caused  by  insufficient  range  of 
draw-tube. 

Many  years  ago  the  late  Dr.  Van  Heurck  used  what  he 
called  a  "  transformer,"  for  the  purpose  of  enabling  short- 
tube  objectives  to  work  on  the  long  tube,  and  vice  versa.  I 
do  not  know  that  he  used  it  for  any  other  purpose,  or  with 
a  view  of  compensating  for  insufficient  range  in  the  draw- 
tube. 

He  applied,  behind  the  objective,  a  lens  of  small  power,  either 
convex  or  concave,  according  to  the  effect  desired,  and  stated 
that  in  this  way  he  was  able  to  use  even  a  2-mm.  Apochromat, 
corrected  for  the  short  tube,  on  the  long  tube,  without  any 
appreciable  loss  of  definition.  The  lenses  he  used  were,  I  believe, 
achromatic. 

But  it  has  occurred  to  me  that  the  utility  of  this  device  is  of 
far  wider  range  than  this.  In  the  course  of  a  series  of  experi- 
ments with  a  large  number  of  dry  objectives  of  various  (high) 
powers,  I  have  found  that  it  is  possible  to  increase  very  greatly 
the  range  of  thickness  of  cover-glass  through  which  the  objective 
will  give  good  definition  ;  and  I  hope,  later  on,  to  show  another 
use  for  this  additional  lens,  which  has  not,  so  far  as  I  am  aware, 
been  described  before. 

If  a  convex  or  concave  lens  of  low  power  be  introduced  im- 
mediately behind  the  objective,  it  has  the  effect  of  altering  the 
degree  of  convergence  of  the  rays  of  light  projected  by  the  back 
lens  of  the  objective,  and  thus  of  altering  the  position  in  which 
the  image  is  formed.  Conversely,  if  the  objective  requires,  to 
give  good  definition,  that  the  image  should  be  formed  in  a  plane 
either  within,  or  beyond,  the  available  limits  of  the  tube,  it  is 
perfectly  possible,  in  the  great  majority  of  cases,  to  find  a  lens 
of  such  a  power  that  its  introduction  above  the  objective  will 
bring  the  image  within  the  limits  of  the  tube. 

Suppose,  for  example,  that  we  have  a  cover-glass  so  thick  that 
the  objective  will  only  form  a  perfect  image  of  the  object  at  a 
point  too  close  to  the  back  lens  for  the  tube  to  be  sufficiently 
shortened  ;  it  is  true  that  we  can,  by  using  the  focusing  adjust- 
ments, bring  the  image  to  the  top  of  the  tube,  but  then  we  do 
not  get  a  perfect  image  ;    that  is  to  say,  not  perfect  in  the  sense 


M.    A.    AINSLIE    OX    AX    ADDITIOX   TO    THE    OBJECTIVE.  565 

that  it  is  the  best  that  the  objective  will  do.  A  perfect  image 
is  only  formed,  for  any  given  thickness  of  the  cover-glass,  at  one 
particular  distance  from  the  back  lens,  and  at  no  other. 

To  take  a  numerical  example,  which  will  probably  help  to  make 
this  point  clearer,  suppose  we  have  a  cover-glass  so  thick  that 
the  correct  tube-length  is  no  more  than  100  mm.  It  is  obvious 
that  the  tube  cannot  be  closed  down  as  much  as  this,  except  on 
a  stand  of  very  exceptional  construction. 

To  treat  the  objective  for  the  moment  as  an  animate  thing, 
we  can  as  it  were  leave  it  under  the  impression  that  it  is  forming 
the  image  at  the  point  where  it  can  do  so  best,  i.e.  at  100  mm. 
from  the  bottom  of  the  tube.  If  we  now  introduce  behind  the 
back  lens  a  concave  lens  of  low  power,  we  decrease  the  conver- 
gence of  the  beam  projected  by  the  objective.  This  in  no  way 
affects  the  working  of  the  objective,  since  the  action  of  this  new 
lens  does  not  commence  until  the  objective  has  finished  its  work  ; 
but  if  the  power  of  the  additional  lens  is  suitably  chosen,  we 
can  so  alter  the  degree  of  convergence  of  the  beam  of  light  as 
to  make  it  come  to  a  focus,  say,  at  a  distance  of  170  mm.  from 
the  back  lens — that  is  to  say,  well  within  the  limits  of  an  ordinary 
draw-tube.  We  have,  in  fact,  altered  the  tube-length  for  which 
the  objective  is  corrected.  If  the  thickness  of  the  cover-glass 
be  still  further  increased,  we  have  only  to  introduce  a  lens  of 
shorter  focus,  and  therefore  of  greater  power,  to  bring  the  image 
within  the  limits  of  the  draw-tube  as  before  ;  and  it  will  readily 
be  seen  that  this  gives  us  the  power,  within  somewhat  wide 
limits,  of  obtaining  good  definition  through  a  thickness  of  cover- 
glass  which  would  in  ordinary  conditions  be  a  complete  bar  to 
anything  like  good  definition. 

Conversely,  if  the  cover-glass  is  inordinately  thin,  the  distance 
at  which  the  perfect  image  will  be  formed  may  be  considerably 
beyond  any  length  that  the  draw-tube  will  reach  ;  but  the 
introduction  of  a  convex  lens  of  suitable  power  will  increase  the 
convergence  of  the  beam  of  light,  and  so  bring  the  image  to  a 
distance  at  which  the  draw-tube  can  deal  with  it. 

Figs.  I.  and  II.  are  intended  to  illustrate  the  action  of  the 
additional  lens  ;   in  each  figure, 
P  is  the  object  ; 

O  is  the  objective,  shown  diagrammatically  as  a  single  lens 
C  is  the  cover-glass  (thick  in  I.,  thin  in  II.)  ; 


566         M.    A.    AINSLIE    ON   AN    ADDITION    TO    THE    OBJECTIVE. 

A  is  the  additional  lens  (concave  in  I.  for  a  thick  cover,  convex 
in  II.  for  a  thin)  ; 

U  and  L  are  the  upper  and  lower  limits,  respectively,  of  the 
draw-tube  ;  the  image  must  be  formed  between  these  limits  to 
be  capable  of  being  focused  by  the  eyepiece  ; 

Vis  the  point  at  which  the  objective  must  produce  the  image, 
if  it  is  to  be  the  best  possible  ;  it  will  be  seen  that  in  each  case  V 
lies  outside  the  limits  of  the  draw- tube,  so  that  the  best  possible 
image  could  not  be  focused  by  the  eyepiece  ; 

T  is  the  point,  well  within  the  limits  of  the  draw-tube,  to  which 
the  image  V  is  transferred  by  the  additional  lens. 

The  actual  path  of  the  rays  is  in  each  figure  shown  by  dark  lines ; 
the  broken  lines  show  the  paths  that  would  be  followed  in  the 
absence  of  the  additional  lens. 

It  would,  no  doubt,  be  possible,  by  the  use  of  the  focusing 
adjustments  of  the  microscope,  to  bring  an  image  of  a  sort,  in 
either  case,  within  the  limits  U,  L  ;  but  it  would  not  be  the  best- 
possible,  indeed  in  the  majority  of  cases  it  would  be  very  inferior, 
owing  to  the  tube-length  being  incorrect ;  the  function  of  the 
additional  lens  is  to  allow  the  objective  to  work  at  the  proper 
tube-length  OV,  but  to  bring  the  "  best  possible  "  image,  formed 
at  the  proper  tube-length,  within  the  available  limits  of  the  draw- 
tube. 

With  objectives  of  not  too  high  power — the  ordinary  l/6th- 
in.,  for  example — there  is  scarcely  any  limit  to  the  amount 
of  correction  which  can  be  produced  in  this  way.  Take, 
for  instance,  an  objective  (Watson  4  mm.  Apochromat, 
N.A.  0'85)  corrected  in  the  usual  way  to  work  through  a 
cover-glass  0'18  mm.  in  thickness,  working  on  an  uncovered 
object,  and  it  will  be  seen  that  the  definition  is  good.  In 
this  case  a  convex  lens  of  +  4  diopters  is  placed  behind  the 
objective.  WTith  a  dry  l/8th-in.,  however,  or  with  dry  ob- 
jectives of  still  higher  power,  it  is  not  possible  to  go  quite 
so  far  as  this,  though  the  results  to  be  obtained  are  by  no 
means  bad. 

I  am  showing  the  objective  working  on  an  uncovered  object 
with  a  view  of  demonstrating  the  amount  of  correction  that 
may  be  obtained  in  this  way  ;  at  the  same  time  I  ought  to 
say  that  this  is  not  the  best  way  of  making  an  ordinary  objective 
work  on  an  uncovered  object :  the  best  and  easiest  method  is  by 


u 


u 


4^^^A 


O 

c 


II 


567 


568       M.    A.    AINSLIE    ON   AN    ADDITION   TO    THE    OBJECTIVE. 

oiling  to  the  front  lens  a  small  piece  of  cover-glass  of  the  thickness 
for  which  the  objective  is  corrected,  which  will  enable  it  to  work 
exactly  as  it  was  intended  to  work.  As  far  as  the  aberrations 
produced  are  concerned,  it  is  a  matter  of  indifference  whether 
we  place  the  cover-glass  next  to  the  object  or  next  to  the 
front  lens  ;  and  the  advantage  of  oiling  it  to  the  front  lens 
is  that  there  are  no  reflections  introduced  to  dull  the  image. 

If   the   precise  change  in  tube-length  necessary  for  a  given 
change  in  the  thickness  of  the  cover-glass  were  known  in  the 
case  of  a  given  objective,  there  would  be  no  difficulty  in  calcu- 
lating   the  power  of  the  additional  lens  required  to    effect  the 
correction  ;  but,  as  has  been  seen,  objectives  vary  so  enormously 
in  this  respect  that  it  is  of  little  use  to  give  any  rules  for  the 
purpose.     Each  objective  ought  to  be  fitted  with  appropriate 
lenses,  just  as  a  defective  eye  has  to  be  fitted  with  spectacles 
Speaking   generally,   it   will   be   found   that  with   the   ordinary 
l/6th-in.,  a  pair  of  lenses,  convex  and  concave,  if  about  10-in. 
focus,  or  -f-  and  —  4  diopters,  will  cover  all  the  ground  likely 
to  be  required.     With  lenses  of  this  power,  and  a  range  of  tube- 
length  from  167  to  259  mm.,  I  find  that  a  Watson  l/6th-in.,  of 
N.A.  0*74,  corrected  normally  for  a  tube-length  of  200  mm.,  and 
a  cover-glass  0*18  mm.  thick,  will  give  good  definition  with  any 
thickness  of  cover-glass  from  zero  to  0*35  mm. ;  with  a  concave 
lens  of  10  diopters,  or  4-in.  focus,  the  thickness  can  be  as  much 
as  \  mm.     Without  the  additional  lens,  the  variations  of  thickness 
of  cover-glass  which  can  be  allowed  for  with  the  above  range 
of  draw-tube  is  from  0*11  to  0'21  mm.,  so  that  the  introduction 
of  the  lenses  of   -f-  and  —   4  diopters  has   more  than  trebled 
the  range  of  thicknesses  through  which  the  objective  will  work. 
This  particular  objective  is  rather  a  favourable  example,  since 
its   sensitiveness    to  cover-glass  thickness  is  less  than  that  of 
many  objectives  of  its  power ;   but  with  any  objective  of  this 
power,  and  to  a  somewhat  less  extent  with  objectives  of  higher 
power,  the  advantage  of  this  device  is  evident.     With  objectives 
of    higher   powers,  the  available  range    of    thicknesses  is  less, 
unless  the  power  of  the  additional  lens  is  raised  ;    for  example, 
a  Leitz  No.  7  cannot  be  made  to  work  on  uncovered  objects 
in  this  way  unless  with  a  convex  lens  of   at   least  10  diopters 
power,    or  4-in.  focus,  and  even  then  the  result  is  not  nearly 
so  good  as  in  the  case  of  a  l/6th-in.     This  again  illustrates  the 


M.    A.    AIXSLIE    ON   AN    ADDITION   TO   THE    OBJECTIVE.        569 

advantages  possessed  by  objectives  of  medium  power  over  those 
of  very  high  power. 

It  will  be  seen  then,  I  think,  that  this  device  places  a  con- 
siderable power  of  correcting  for  cover-glasses  of  abnormal 
thickness  in  the  hands  of  the  microscopist,  especially  with  the 
miserable  50  mm.  range  of  the  Continental  draw-tube  ;  and  it 
now  remains  to  be  seen  what  the  effect  of  this  additional  lens  is 
on  the  power,  N.A.,  and  corrections,  spherical  and  chromatic, 
of  the  objective. 

Firstly,  as  regards  the  power.  If  the  additional  lens  could  in 
practice  be  fitted  in  the  ;'  upper  focal  plane  "  of  the  objective — • 
that  is  to  say,  in  the  plane  in  which  a  pencil  of  parallel  rays 
entering  it  from  below  would  come  to  a  focus — there  would  be 
no  alteration  of  power.  But  in  most  objectives — in  all  those  of 
high  power,  in  fact — this  upper  focal  plane  is  not  far  behind 
the  front  lens,  and  therefore  inaccessible.  So  we  have  to  put 
up  with  a  certain  increase  of  power  in  the  case  of  the  concave 
lens,  and  a  decrease  in  the  case  of  the  convex  ;  but  if  the  power 
of  the  additional  lens  does  not  exceed  4  diopters  either  way,  i.e. 
if  its  focal  length  is  not  less  than  10  in.,  the  alteration  of  power 
is  not  serious.  It  is  an  advantage  to  have  the  additional  lens  as 
near  as  possible  to  the  back  lens  of  the  objective,  but  if  there 
is  any  difficulty  in  fitting  it  there,  it  does  very  well  to  place  it 
on  the  nosepiece. 

The  effect  on  the  working  distance  of  the  objective  is  not 
serious  :  the  concave  lens  increases  the  working  distance,  and 
the  convex  lens  diminishes  it ;  but  since  the  former  is  used  in 
the  case  of  thick  cover- glasses,  and  the  latter  in  the  case  of 
thin,  it  will  be  seen  that  the  change  is  in  the  right  direction,  so 
that  this  point  need  not  worry  us. 

Similarly  the  effect  on  the  N.A.  is  not  great.  The  convex 
lens  somewhat  diminishes  it,  and  the  concave  lens  may  (it  does 
not  always)  slightly  increase  it ;  but  the  change  is  not  great, 
and  for  most  purposes  unimportant. 

It  is  of  more  importance  to  inquire  what  effect,  if  any,  the 
introduction  of  the  additional  lens  has  on  the  spherical  and  chro- 
matic corrections.  To  take  the  former,  it  so  happens  that  the 
spherical  aberration  introduced  by  the  additional  lens  slightly 
counteracts  its  effect  in  producing  the  result  desired  ;  a  simple 
uncorrected  lens  does  not  quite  produce  the  full  theoretical  effect 


570       M.    A.    AINSLIE    ON    AN   ADDITION   TO    THE    OBJECTIVE. 

it  would  have  if  it  were  corrected  for  spherical  aberration  ;  but 
in  any  case  the  additional  lens  is  small,  and  of  low  power,  so  that 
the  effect  of  its  spherical  aberration  is  very  slight,  and  only  in- 
volves a  small  movement  of  the  draw-tube.  Since  the  final 
adjustment  of  the  draw-tube  would  in  any  case  be  performed  by 
actual  inspection  of  the  image,  it  will  be  easily  realised  that  the 
effect  of  the  spherical  aberration  of  the  additional  lens  is  quite 
unimportant. 

With  regard  to  the  chromatic  effect,  I  have  only  used  simple 
uncorrected  lenses  in  my  experiments.  Even  with  these,  the 
effect  on  the  colour  correction  of  the  objective  is  extremely 
small,  except  perhaps  in  the  case  of  an  additional  lens  of 
10  diopters. 

The  only  effect  that  is  at  all  noticeable  is  that  with  the  convex 
lens  in  use  the  "compensation'  required  in  the  eyepiece,  to 
do  away  with  the  chromatic  difference  of  magnification  (present 
in  all  lenses  having  a  single  front  lens)  is  somewhat  diminished  ; 
in  the  case  of  the  concave  lens,  it  is  somewhat  increased  ;  but 
this  effect  is  only  seen  if  specially  looked  for,  and  with  ordinary 
Huyghenian  eyepieces  would  not  be  noticed. 

There  is,  however,  a  curious  effect  to  be  seen  in  some  cases, 
with  objectives  which  under  normal  conditions  show  a  certain 
blue  tint  on  the  margins  of  black  objects ;  and  many  of 
the  finest  achromatic  lenses  of  the  present  day,  noticeably 
Watson's  Holoscopic,  show  this  effect,  which  indeed  I  am  informed 
betokens  a  more  than  usually  good  spherical  correction,  and 
in  consequence  more  than  usually  good  definition.  I  have  a 
Holos  25  mm.  objective,  of  measured  N.A.  0'31,  corrected  for  the 
250  mm.  tube  ;  this,  on  black  objects,  such  as  the  lines  on  the 
Abbe  test  plate,  shows  the  blue  tint  I  have  alluded  to.  When  the 
correction  of  this  lens  is  altered  to  the  short  tube  by  the  intro- 
duction of  a  convex  lens  of  2  diopters  (20  in.  focus),  the  blue  tint 
almost  disappears,  and  the  total  quantity  of  outstanding  colour 
is  greatly  diminished,  so  that  the  additional  lens  has  a  sort  of 
"  apochromatising '  effect ;  this  is  probably  due  to  the  fact 
that  the  additional  lens  slightly  alters  the  'k  preferred  colour," 
for  which  the  spherical  correction  of  the  objective  is  carried 
out ;  but  to  my  eyes  there  is  little,  if  any,  loss  of  definition  on 
this  account,  and  the  27  compensating  eyepiece  can  still  be  used 
with  advantage. 


M.    A.    AIXSLIE    ON    AN    ADDITION    TO    THE    OBJECTIVE.        571 

The  additional  lenses  above  described  are  easily  fitted  behind 
the  objective  if  they  are  mounted  in  small  cells  which  push 
into  a  ring  made  to  screw  to  the  nosepiece,  and  having  a  thread 
in  front  to  take  the  objective.  Otherwise  they  may,  as  stated 
above,  be  fitted  immediately  behind  the  back  lens,  and  almost 
in  contact  with  it ;  but  this  is  hardly  necessary,  unless  it  is 
important  that  the  power  of  the  objective  should  be  affected  as 
little  as  possible.  The  lenses  I  have  had  made  are  just  over 
1-i  mm.  in  diameter,  and  the  outside  diameter  of  their  cells  is 
rather  less  than  15*5  mm.,  so  that  there  is  ample  room  for 
them  to  push  into  the  upper  side  of  the  ring  suggested,  leaving 
sufficient  thickness  in  the  ring  for  the  thread  to  fit  the  nose- 
piece. 

They  were  beautifully  made  and  fitted  for  me  by  Messrs. 
H.  F.  Angus  &  Co.,  who  supplied  me  with  a  series  of  11  of  these 
lenses,  varying  in  power  from  +10  to  —  10  diopters.  With 
this  series  almost  anything  can  be  done  in  the  way  of  cover- 
glass  correction. 

I  have  tried  both  biconvex  and  biconcave,  and  plano-convex 
and  plano-concave  lenses,  the  latter  with  the  plane  side  both 
upwards  and  downwards,  without  being  able  to  see  any  difference 
in  the  performance  ;  biconvex  and  biconcave  lenses  are  easier 
to  obtain,  and  I  should  recommend  them  to  any  one  thinking 
of  trying  this  device. 

So  far  we  have  been  dealing  with  the  use  of  an  additional  lens 
with  dry  objectives  ;  but  I  now  come  to  a  use  for  this  device 
which  has  not,  as  far  as  I  know,  been  suggested  before.  I  refer 
to  the  conversion  of  an  oil-immersion  objective  into  a  water- 
immersion. 

Some  time  ago  I  found  that  with  certain  oil-immersion  objec- 
tives it  was  possible  to  get  good  definition  with  glycerine  as 
the  immersion  fluid  if  the  tube  length  was  increased  by  60  mm. 
or  so.  Was  it  possible  to  use  these  objectives  as  water-immer- 
sions ? 

The  substitution,  in  the  case  of  an  oil-immersion  objective, 
of  a  medium  of  smaller  refractive  index  for  the  oil  has  an  effect 
on  the  corrections  of  the  objective  precisely  similar  in  kind  to 
the  reduction  in  the  thickness  of  the  cover-glass  in  the  case  of 
a  dry  objective ;    in  each  case  the  effect  is  really  due  to  the 


572       M.    A.    AINSLIE    OX   AN   ADDITION   TO    THE    OBJECTIVE. 

reduction  of  the  average  refractive  index  in  the  space  between 
the  front  lens  and  the  object,  except  that  in  the  case  of  the  sub- 
stitution of  water  for  oil  the  effect  is  greatly  increased. 

It  was  quite  obvious,  the  moment  I  tried  the  experiment,  that 
mere  increase  of  tube-length  would  not  by  itself  make  an  oil- 
immersion  l/12th  work  as  a  water-immersion,  on  any  cover- 
glass  that  was  likely  to  be  met  with  ;  but  as  soon  as  the  idea 
of  the  additional  lens,  as  described  above,  occurred  to  me,  it 
immediately  suggested  itself  as  a  way  out  of  the  difficulty.  But. 
as  a  rule,  in  the  case  of  the  conversion  of  an  oil-immersion  into 
a  water-immersion,  the  power  of  the  additional  lens  has  to  be 
much  greater  than  is  required  with  a  dry  lens,  to  correct  for  an 
unusually  thin  cover-glass.  In  fact,  it  is  generally  necessary 
to  use  a  lens  of  such  great  power  that  the  pencil  of  rays  emerging 
from  the  back  lens  of  the  objective  is  actually  divergent  instead 
of  convergent ;  so  that  the  correct  position  for  the  image  has 
actually  "  passed  infinity  "  and  the  tube-length  is  negative,  or, 
in  other  words,  the  best  image  that  can  be  formed  by  the  ob- 
jective is  a  "virtual  image"  several  inches  below  the  object! 
It  is  hardly  necessary  to  say  that  this  means  upsetting  all  the 
corrections  of  the  objective,  and  at  first  sight  it  does  not  look- 
very  promising. 

But  on  trial  it  was  found  that  it  was  only  the  extreme  margin 
of  the  objective  that  was  adversely  affected.  With  an  illuminat- 
ing cone  of  not  more  than  about  0'75  or  0'8  N.A.,  the  definition 
becomes  quite  satisfactory,  and  it  appears  that  the  central 
portion  of  the  objective  is  not  to  any  great  extent  affected  by 
the  violence  done  to  it. 

Here  again,  as  with  dry  objectives,  an  objective  of  moderate 
power  is  much  more  amenable  to  the  action  of  the  additional 
lens  than  one  of  very  high  power.  The  Zeiss  l/7th-in.,  of  N.A. 
about  0'93,  only  requires  a  convex  lens  of  2  diopters,  or  20  in. 
focus,  to  effect  the  conversion  ;  a  Leitz  l/10th-in.,  the  focus  of 
which  is  about  2*75  mm.  (so  that  it  is  really  a  l/9th-in.),  requires 
8  diopters,  or  5  in.  focus  ;  and  a  Watson  "  Parachromatic  ' 
l/12th-in.  (actually  a  l/14th-in.  of  N.A.  1*30)  requires  a  lens  of 
10  diopters,  or  4  in.  focus.  I  have  not  experimented  with  any 
stronger  lenses,  nor  do  I  think  that  this  arrangement  would  be 
of  much  use  with  such. 


M.    A.    AINSLIE    ON    AN    ADDITION    TO    THE    OBJECTIVE.        573 

Even  if  we  have  to  sacrifice  a  little  of  the  aperture  of  the  lens, 
however,  it  seems  to  me  that  there  is  a  distinct  field  of  utility 
for  this  method  of  conversion.  The  effect  on  the  definition,  at 
any  rate  in  the  centre  of  the  field,  of  the  additional  lens  is  ex- 
tremely small ;  and  with  a  l/12th-in.  oil-immersion,  treated  in 
this  way,  I  have  been  able  to  get  clear  and  strong  resolution 
of  Amphipleura  Lindheimeri  in  styrax,  which,  though  not  an 
exhaustive  test  for  a  water-immersion,  yet  requires  a  pretty 
good  lens  to  give  a  really  good  image. 

The  useful  limit  of  N.A.  for  a  lens  treated  in  this  way  is,  I 
think,  about  1*15.  It  is  not  very  likely  that  the  full  aperture  of 
the  objective  would  be  available,  when  one  considers  that  the 
full  N.A.  of  an  oil-immersion  treated  in  this  way  is  something 
like  1*29  out  of  a  possible  1'33,  and  that  no  water-immersion  has 
so  far  been  put  on  the  market,  even  apo chromatic,  with  a  greater 
N.A.  than  1*25.  If  we  are  content,  however,  to  sacrifice  a  little 
of  the  margin  of  the  lens,  we  can  get  a  good  water-immersion  of 
about  the  aperture  named,  which  should  be  useful  for  occasional 
use  at  any  rate,  when  it  is  not  worth  while  going  to  the  expense 
of  a  proper  water-immersion  objective. 

It  is  a  somewhat  unfortunate,  though  unavoidable,  circumstance 
that  the  introduction  of  the  additional  lens  shortens  the  working 
distance,  considering  the  limited  working  distance  already 
possessed  by  the  average  oil-immersion  ;  at  the  same  time,  the 
l/12th-in.  alluded  to  above  will  work  through  a  cover-glass  as 
much  as  0'20  mm.  thick,  and  it  is  easy  to  obtain  cover-glasses 
thinner  than  this  ;  and  it  appears  to  me  that  it  is  only  on  tem- 
porarily mounted  specimens,  such  as  films  of  living  bacteria, 
and  the  like,  that  one  would  want  to  use  a  water-immersion,  the 
great  superiority  of  an  oil-immersion  on  any  permanently  mounted 
object  being  undeniable. 

For  biological,  medical,  and  other  work  that  requires  the 
examination  of  living  objects,  I  think  there  is  a  real  sphere  of 
usefulness  for  this  method  of  conversion.  But  at  the  same 
time,  it  should  be  noticed  that  the  advantages  of  the  method 
are  more  pronounced  if  the  oil-immersion  objectives  employed 
are  of  medium  power,  and  a  l/10th-in.  is  certainly  more 
suited  to  the  additional  lens  than  a  l/12th-in. 

The  conversion  of  an  oil-  into  a  water-immersion  is  particularly 
useful  when  it  is  desired  to  examine  living  bacteria  on  a  dark 


574        M.    A.    AINSLIE    ON    AN    ADDITION   TO    THE    OBJECTIVE. 

ground.  It  sometimes  happens,  when  an  oil-immersion  is  used 
for  this  purpose,  that  the  cover- glass  has  an  unpleasant  knack 
of  sticking  to  the  front  lens  of  the  objective  ;  with  a  water- 
immersion  this  difficulty  is  absent.  iVlso,  there  is  the  distinct 
advantage  that  it  is  easy  to  remove  the  water  if  it  is  desired 
to  examine  the  object  with  a  dry  lens,  whereas  this  is  by  no 
means  an  easy  matter  in  the  case  of  oil.  The  performance  of 
the  Zeiss  l/7th-in.,  used  as  a  water-immersion,  upon  living 
objects  on  a  dark  ground  is  especially  good,  though  the  Leitz 
l/10th-in.  is  not  far  behind. 

In  the  case  of  an  oil-immersion,  it  is  well  to  have  the  additional 
lens  fitted  as  close  to  the  back  lens  of  the  objective  as  possible  ; 
there  is  no  difficulty  in  doing  this,  as  it  is  usually  the  practice  of 
makers  to  supply  a  '  funnel  stop  '  to  which  the  optical  part 
of  the  objective  can  be  screwed.  If  the  stop  is  removed,  and 
the  additional  lens  fitted  in  its  place,  so  as  to  be  close  to  the 
back  lens  when  the  optical  part  is  screwed  on,  the  effect  on  the 
magnifying  power  is  not  serious,  and  can  be  disregarded.  In 
the  case  of  the  Leitz  1/lOth-in.,  for  example,  the  objective  in 
its  normal  state  has  a  focal  length  of  2"75  mm.,  and  is  a  l/9th-in.  ; 
with  a  lens  of  +  8  diopters  in  position  immediately  behind  the 
back  lens,  the  focal  length  is  3  mm.,  and  the  objective  becomes 
a  l/8th-in. 

For  dark-ground  work,  of  course,  the  aperture  must  be  reduced 
to  something  like  0*85,  with  the  dark-ground  illuminators  of  the 
present  day  ;  and  we  may  either  fit  a  separate  "  funnel  stop  " 
with  a  small  lens  in  it,  giving  this  aperture,  or  use  the  funnel 
stop  as  it  stands,  and  fit  the  lens  in  rear  of  the  objective  mount. 
This,  of  course,  reduces  the  power  rather  more  than  the  other 
arrangement,  but  this  is  not  serious,  as  sufficient  power  can  be 
obtained  by  the  use  of  a  deeper  eyepiece. 

It  should  be  noted  that  when  the  oil-immersion  has  been 
converted  in  this  way  to  a  water-immersion,  it  becomes  sensitive 
to  variations  in  the  thickness  of  the  cover-glass,  though  not  to 
the  same  extent  as  a  dry  objective  ;  the  draw- tube  will  as  a 
rule  be  able  to  deal  with  this,  but  if  more  correction  is  required 
it  can  be  obtained  by  means  of  additional  lenses,  in  the  manner 
described  above  for  dry  objectives. 

I  have  left  to  the  last,  principally  because  it  is  more  inter- 
esting than  practically  useful,  what  is,  from  the  "  brass  and 


M.    A.    AIXSLIE    ON    AX    ADDITION    TO    THE    OBJECTIVE.        O/O 

glass  "  point  of  view,  perhaps  the  most  remarkable  use  to  which 
the  additional  lens  can  be  put. 

This  is  the  conversion  of  a  dry  objective  into  an  oil-immersion. 
In  the  great  majority  of  cases  this  cannot  be  done,  not  only 
because  it  is  too  radical  a  change  for  most  objectives,  but  because 
the  working  distance  is  as  a  rule  too  great  to  admit  of  oil-contact. 
But  there  are  certain  objectives  of  comparatively  low  power, 
and  small  working  distance,  with  which  it  is  possible.  The 
matter  only  occurred  to  me  a  day  or  two  ago,  so  that  I  have  not 
had  the  opportunity  of  trying  the  experiment  with  more  than  two 
lenses  ;  with  one  of  these,  however,  a  6-mm.  Holos  of  the  earlier 
construction,  having  an  N.A.  of  0*84,  I  succeeded  fairly  well. 

The  additional  lens  required  is  a  concave  of  —  10  diopters  ; 
with  this,  though  the  field  is  much  curved,  and  good  definition 
can  only  be  obtained  in  the  centre,  the  effect  is  quite  good. 

It  will  be  realised  that  the  substitution  of  oil  for  air  between 
the  front  lens  and  the  cover-glass  is  optically  equivalent  to  the 
thickening  of  the  cover-glass  so  as  to  fill  the  wThole  space  between 
the  object  and  the  front  lens  :  it  might  be  expected,  therefore, 
after  wThat  has  been  said,  that  the  power  of  the  additional  lens 
required  would  be  considerable  ;  and  I  doubt  whether  the  effect 
could  be  obtained  with  a  l/6th-in.,  except  perhaps  with  one 
of  very  short  working  distance. 

The  advent  of  the  Zeiss  l/7th-in.  oil-immersion  drew  atten- 
tion to  the  better  resolution  given  by  an  oil-immersion  over  that 
given  by  a  dry  objective  of  the  same  aperture  ;    but  I  did  not 
expect  that  this  would  hold  good  with  such  an  arrangement  as 
that  here  described.     I  was  much  surprised,  therefore,  to  find 
that  it  was  possible  to  resolve  A.  Lindheimeri  with  a  solid  axial 
cone  of  illumination,  the  longitudinal  and  transverse  striae  being 
quite  plain  with  a  compensating  eyepiece  16*5.     In  this  specimen 
the  striae  run  about  70,000  to  the  inch,  and  it  is  a  very  severe 
test,  under  the  conditions  of  illumination  mentioned,  for  any 
dry  lens ;  it  is,  of  course,  too  hard  for  the  6  mm.  Holos  in  its 
dry   state,   the   aperture    being   insufficient.     The  introduction 
of  the  convex  lens  increases  the  N.A.  to  about  0'89  ;  but  I  think 
it  is  safe  to  say  that  no  dry  lens  of  this  aperture  would  effect 
the  resolution  with  central  light,  though  a  much  smaller  aperture 
will  suffice  with  oblique  light.     In  this  case,  then,  the  conversion 
to  an  oil-immersion  affords  a  distinct  gain. 


576       M.    A.    AIXSLIE    ON    AN   ADDITION    TO    THE    OBJECTIVE. 

I  have  also  tried  to  effect  the  conversion  in  the  case  of  a  Holos 
4  rnm.  of  N.A.  0'95  ;  but  in  this  case  it  was  impossible,  even  with 
lenses  of  a  total  power  of  18  diopters,  which  is  far  too  powerful, 
and  upsets  the  objective  altogether. 

This  application  of  the  additional  lens,  therefore,  I  think  is  of 
theoretical  interest,  but  hardly  of  practical  value. 

I  think  that  this  device  of  the  additional  lens  is  worthy  of 
extended  trial,  both  for  the  purpose  of  correcting  for  the 
thickness  of  the  cover-glass,  and  for  the  conversion  of  an  oil- 
immersion  into  a  water-immersion.  I  shall  be  gratified  if  it 
should  prove  of  use  to  any  one  in  practical  work,  and  should 
be  glad  to  hear  that  some  one  has  taken  it  up. 




Journ.  Quekttt  Microscopical  Club,  Ser.  2,  Vol.  XII.,   No.  77,  November  1915. 


577 


NOTES   ON    DIATOM   STRUCTURE. 

By  A.  A.  C.  Eltot  Merlin,  F.R.M.S. 

{Read  April  21th,   1915.) 

I  venture  to  bring  to  your  notice  a  very  beautiful  form  of 
tertiary  structure  which  I  have  recently  found  on  a  variety  of 
Aulacodiscus  Comberi  from  Oamaru.  The  valve  is  on  a  styrax 
type-slide  of  230  forms  from  that  locality  and  is  covered  with 
a  network  of  dark,  well-defined  secondaries,  except  on  the  parts 
occupied  by  the  large  primaries.  Each  of  the  dark  secondaries 
has  been  found  to  be  split  up  into  three  or  four  parts  by  a  bright 
cross-bar  arrangement.  This  structure  requires  a  good  oil- 
immersion  objective  and  a  very  considerable  magnification  to 
render  it  readily  discernible,  but  it  is  in  no  way  a  glimpse  object, 
and  when  well  seen  reminds  one  of  the  bridges  of  bright  matter 
that  are  frequently  observable  crossing  the  umbrae  of  sunspots. 
Photograph  No.  1  exhibits  clear  indications  of  the  structure 
in  question,  x  2,150  diameters,  although  it  cannot  be  photo- 
graphed as  plainly  as  it  can  be  demonstrated  visually.  Inci- 
dentally the  photograph  serves  to  prove  the  fact  that  with  a 
power  of  2,150  diameters  there  is  no  excess  of  "  empty  magnifica- 
tion," when  employing  a  good  lens  of  1*4  N.A.,  for  few  will 
comfortably  see  the  structure  therein  without  the  aid  of  a  low- 
power  magnifier.* 

Two  other  photographs  are  sent  herewith  for  your  inspection. 
These  were  secured  under  the  following  circumstances.  Mr. 
Nelson  wrote  to  me  that  he  had  discovered  that  Coscinodiscus 
Simbirskii,  which  with  ordinary  transmitted  light  resembles  Cos- 
cinodiscus asteromphalus,  looks  like  Actinoptychus  splendens  when 

*  The  photographs  referred  to  in  this  paper  contain  details  of  such 
a  nature  that  only  a  drawing  could  adequately  represent  them  for 
purposes  of  reproduction. 

Journ.  Q.  M.  C,  Series  II. — No.  77.  32 


578  A.    A.    C.    ELIOT   MERLIN    ON   DIATOM   STRUCTURE. 

examined  with  dark-ground  illumination  and  a  rather  small  stop. 
This  led  me  to  search  my   Coscinodiscus  genus  circle  slide  for 
the  diatom  mentioned.  Although  this  could  not  be  found,  another 
form  was  noted  appearing  with  transmitted  light  as  in  photo- 
graph No.  2   (x    295),  while  with  dark-ground  illumination  a 
beautiful   radiating  structure,    somewhat   resembling    A.  helio- 
pelta,  was  revealed,  which  photograph  No.  3,  taken  at  the  same 
magnification,    inadequately   represents.     Print   No.    2   fails    to 
show  a  fine  dotted  structure  which  exists  all  over  the  valve 
and  can  be  detected  in  parts  of  No.  3.     Print  No.  2  should  make 
the  identification  of  this  specimen  easy  from  its  very  marked 
peculiarities.*     These   photographs  were  taken  with  a  16-mm. 
apochromat  of  0'35  N.A.  and  a  x  6  projection  eyepiece. 

In  connection  with  diatoms  as  test-objects  there  is  an  interest- 
ing point,  to  me  at  least,  on  which  I  have  been  able  to  find  no 
definite  information  in  the  microscopical  works  in  my  possession. 
I  am  alluding  to  the  exact  period  during  which  the  fine  structure 
of  the  diatom  valve  was   first  employed  as  a  test-object.     Are 
we   approaching   the   centenary   of   its   discovery,   a   discovery 
which  has  perhaps  influenced  more  than  any  other  the  progress 
towards   perfection   of   the    modern   microscope   stand   and   its 
optical  parts  ?   The  oldest  work  on  the  microscope  in  my  library 
is  the  Microgr aphia  Restaur ata,  published  in  1745.|     This  makes 
no  mention   of   diatoms,   so  that  it  may  be  taken  for  granted 
that  Dr.  Hooke  did  not  include  "  diatom-dotting  "  amongst  his 
' '  Wonderful  Disco  veries  by  the  Microscope ' '  therein  detailed.  George 
Adams  published  the  fourth  edition  of  his  Micrographia  Illustrata 
in  1771  and  also  failed  to  include  diatoms  amongst  the  numerous 
objects  described  in  his  interesting  book,  although  many  quaint 
aquatic  organisms    are    dealt  with  at  considerable  length,  even 
including    '  a  new  sort  of  animalcula  found  in  an  infusion  of 

*  C.  Ludovicianus  (Rattray)  from  Jutland. 

f  Dr.  Robert  Hooke,  M. A.,  F.R.S.  (1635-1703),  Micrographia,or  some 
Physiological  Descriptions  of  Minute  Bodies  made  by  Magnifying 
Glasses,  with  Observations  and  Inquiries  thereupon.  The  first  edition 
was  published  in  London,  1665. 


A.    A.    C.    ELIOT   MERLIN    ON   DIATOM   STRUCTURE.  579 

blue-bottles."  We  may  thus  assume  that  diatoms  had  not  at 
that  period  appeared  on  the  scene  to  trouble  the  optician  ' '  at 
the  Sign  of  Tycho  Brahe's  Head,  No.  60,  in  Fleet  Street,  London." 
Then  who  was  the  first  man  to  dot  the  first  diatom  ?  *  Possibly 
Dr.  Goring,  who,  "  is  said  to  have  discovered  that  the  structure 
of  certain  bodies  could  be  readily  seen  in  some  microscopes 
and  not  in  others.  These  bodies  he  named  test-objects ;  he  then 
examined  these  tests  with  the  achromatic  combination  before 
noticed,  and  was  led  to  the  discovery  of  the  fact  that  the  pene- 
trating power  of  the  microscope  depends  upon  its  angle  of 
aperture  "  (vide  Quekett's  Practical  Treatise  on  the  Use  of  the 
Microscope,  second  edition,  p.  38). f  Be  this  as  it  may,  several  test 
diatoms  are  beautifully  figured  on  PL  9  of  Quekett's  book,  and 
it  is  instructive  to  note  that  P.  angulatum  shown  therein  is  the 
Humber  form  with  smoothly  rounded  outline  and  not  the  species 
now  known  as  P.  quadratum,  which,  I  am  told,  was  the  original 
true  P.  angulatum  as  first  found  and  named.  Of  course  "  diatom- 
dotting  '  was  far  advanced  in  Quekett's  time.  He  recom- 
mends the  Navicula  hippocampus  as  an  excellent  test  for  a  l/4th- 
inch  objective-glass,  stating  that  it  should"  show  distinctly  both 
sets  of  lines  or  dots  by  oblique  illumination."  The  younger 
members  of  this  club  may  not  realise  that  first-class  l/4th-inch 
objectives  made  in  1850  have  apertures  slightly  exceeding  0*7  N.A. 
and  will  cleanly  and  clearly  dot  P.  angulatum  with  axial  critical 


*  Extract  from  Messrs.  Sollitt  &  Harrison's  paper  read  before  the 
British  Association  at  Hull,    1853  : 

"  We  in  Hull  first  discovered  the  delicate  markings  on  their  silicious 
coverings  and  pointed  them  out  to  others  as  the  proper  tests  for  lenses. 
The  first  of  the  Diatomaceae  on  which  the  lines  were  seen  was  the 
Navicula  hippocampus  of  Ehrenberg.  .  .  .  This  discovery  was  made 
early  in  1841,  when  specimens  were  sent  to  the  Microscopical  Society  of 
London  .  .  .  also  to  Mr.  Smith,  Mr.  Ross,  Messrs.  Powell  &  Lealand. 
M.  Nachet  in  Paris  and  Professor  Baily  in  America,  the  whole  of 
whom  at  once  saw  the  excellency  of  those  objects  as  tests  for  the 
microscope.  Indeed  they  are  without  doubt  to  the  microscope  what 
the  close  double  stars  are  to  the  telescope." — E.  M.  Nelson. 

f   First  edition  published  1848. 


580  A.    A.    C.    ELIOT    MERLIN    ON    DIATOM    STRUCTURE. 

illumination,  but  such  lenses  were  much  more  expensive  than  those 
made  to-day  of  equal,  or  superior,  optical  performance.  Still, 
it  is  as  well  to  bear  in  mind  that  in  1850  thoroughly  well-corrected 
dry  achromatic  lenses  up  to  0*90  N.A.  were  obtainable  (Powell's 
l/16th-inch  of  that  date  has  the  last-mentioned  aperture),  and 
were  capable  of  resolving  most  of  the  present  well-known  tests 
with  the  exception  of  the  A.  pellucida,  this  being  first  resolved 
(according  to  Dr.  Carpenter)  by  one  of  Powell  &  Lealand's 
water-immersion  objectives  which  that  firm  commenced  con- 
structing in  1868. 


Jvurn.  Qiuketl  Microscopical  Club,  tier.  2,  Vol.  XII.,   No.  77,  November  1915. 


581 


A   NOTE   ON   THE  SLIDES  OF   FISSIDENTACEAE    IN 

THE   Q.M.C.   CABINET. 

By  G.  T.  Harris. 

(Read  May  'loth,   1915.) 

Communicated  by  Clarence  J.  H.  Sidwell,  F.R.M.S. 

In  Dixon's  Student's  Handbook  of  British  Mosses  the  Fissi- 
dentaceae  of  Great  Britain  comprise  fourteen  species  and  about 
five  well-marked  varieties.  Of  these  fourteen  species  eight 
are  represented  in  the  Cabinet  of  the  Quekett  Microscopical 
Club,  and  of  these  eight  four  at  least  are  rare,  and  several  very 
rare.  Fissidens  exilis  is  the  smallest  of  our  native  species  and 
is  often  found  accidentally  among  some  gathering  of  quite 
another  moss  when  examination  takes  place  at  home.  There 
is  no  difficulty  in  recognising  it  owing  to  its  minute  size  and 
non-bordered  leaves.  Fissidens  viridulus  is  very  slightly  larger 
than  exilis,  but  has  the  leaves  distinctly  bordered  with  a  narrow 
cartilaginous  border,  which  is  usually  lost  at  the  apex ;  the 
variety  Lylei,  however,  may  be  confused  with  exilis,  as  it  is 
very  minute  and  has  no  border  except  on  the  sheathing  laminae, 
indeed  it  has  been  made  a  separate  species  by  some  authors. 
It  has  been  proposed  to  unite  the  species  viridulus,  pusillus,  and 
incurvus  under  one  specific  type,  as  intermediate  states  are 
often  met  with.  Fissidens  incurvus  var.  tamarindifolius  also 
at  one  time  had  specific  rank,  but  is  now  generally  accepted  as 
a  variety  of  incurvus.  It  is  usually  found  sterile  and  has  a  quite 
distinct  facies  when  growing,  that  readily  assures  it  recognition. 


582  G.    T.    HARRIS,    NOTE    ON    THE    SLIDES    OF 

On  closer  examination  the  broad,  distant  leaves  are  quite  dis- 
tinctive. 

Fissidens  algarvicus  (Solms.)  was  first  recorded  for  the  British 
Isles  by  Mr.  G.  B.  Savery  at  Silverton,  S.  Devon.  It  has  later 
been  found  near  Cheltenham.  Originally  found  in  Portugal, 
it  appears  to  reach  in  England  its  most  northerly  limit.  It  is 
interesting  to  note  that  a  very  closely  allied  species,  Fissidens- 
Orrii  (Lindb.)  (=  F.  tequendamensis,  Mitt.),  was  recorded  in 
1854  from  Dublin.  Dr.  Braithwaite  pointed  out  the  suspicious 
proximity  to  the  locality  of  the  Glasnevin  Botanic  Gardens, 
and  certainly  the  species  so  far  has  not  been  refound,  so  is  ex- 
cluded from  the  British  Moss  Flora. 

Fissidens  bryoides  is  at  once  the  commonest  and  most  variable 
of  our  species.  The  border  is  usually  strong  and  continuous 
to  the  apex,  where  are  a  few  minute  denticulations.  It  varies 
considerably  in  size  from  a  quarter  of  an  inch  to  an  inch  or  more 
in  height.  It  is  densely  gregarious,  and  it  is  not  difficult  to 
recognise  it  by  its  general  habit  and  habitat  after  a  little  experi- 
ence. The  form  inconstans  has  the  fruit  sometimes  terminal,, 
at  other  times  lateral,  but  its  leaves  and  structure  remain 
fairly  true  to  type. 

Fissidens  Curnowii  was  originally  described  by  Schimper  as 
a  variety  of  bryoides  under  the  name  caespitans,  but  Mitten 
later  raised  it  to  specific  rank  as  Fissidens  Curnowii  in  honour 
of  W.  Curnow,  who  apparently  first  discovered  it  in  England 
in  1868.  Mr.  H.  N.  Dixon  in  his  Student's  Handbook  of  British 
Mosses  gives  it  an  intermediate  position  as  a  sub-species.  It  is 
a  rare  species  and  the  few  records  for  it  are  from  near  the  sea  in 
the  south-west  of  England,  though  it  has  been  recorded  from 
comparatively  northern  stations. 

Both  Curnow  and  Ralfs    describe  their  localities  as  aquatic. 
My  locality  in  Sidmouth  is  a  damp,  not  wet,  sandstone  cave, 


FISSIDENTACEAE   IN   THE   Q.M.C.    CABINET.  583 

and  I  should  scarcely  have  regarded  it  as  an  aquatic  species 
comparable  with  rivularis  or  crassipes.  It  is  a  handsome  moss, 
usually  fruiting  profusely,  and  thickly  matted  with  purple 
radicles,  though  these  are  not  so  abundantly  developed  in  the 
young  plants  as  in  the  older. 

Fissidens  rivularis,  a  truly  aquatic  moss,  was  originally  found 
by  Mr.  E.  M.  Holmes  at  Hastings  in  1884,  and  this  has  hitherto 
been  the  only  British  station.  Some  time  ago  I  was  fortunate 
in  adding  a  second  station  near  Sidmouth,  which  appears  to  be 
identical  in  physical  conditions  with  Mr.  Holmes's  original  one. 
It  occurs  on  rocks  kept  constantly  wet  by  dripping  water,  and 
in  deep  shade.  Often  it  is  quite  hidden  by  an  overgrowth  of  some 
freshwater  algae,  and  the  fruit  appears  to  be  rare.  The  broad 
yellow  nerve  and  border,  with  its  aquatic  habitat,  sufficiently 
indicate  it. 

Fissidens  polyphyllus  is  another  more  or  less  aquatic  species. 
The  slide  of  this  moss  was  already  in  the  Quekett  Microscopical 
Club  collection,  and  was  sent  to  me  with  other  slides  of  mosses 
for  verification  by  the  Hon.  Curator,  Mr.  Sidwell.  No  locality 
is  given,  but  it  occurs  very  rarely  in  North  Wales,  Devon  and 
Cornwall.  The  fruit  appears  to  be  extremely  rare,  and  has 
perhaps  only  once  been  found,  by  M.  Camus  near  St.  Rivoal 
in  France.  It  is  always  barren  in  England,  or  at  least  has  not 
been  found  fruiting. 

Fissidens  taxifolius  is  a  very  common  species  on  stiff  argil- 
laceous soils,  and  is  one  of  the  most  easily  recognised  of  the 
Fissidentaceae.  These  comprise  the  various  species  of  Fissidens 
at  present  represented  in  the  collection  of  the  Quekett  Micro- 
scopical Club.  I  am  hoping,  however,  that  it  may  be  possible 
to  add  other  species  at  a  later  date,  possibly  to  make  up  the 
entire  series. 

The  genus  is  a  very  natural  and  distinctive  one  owing  to 


584       G.    T.    HARRIS,    NOTE    OX    SLIDES    OF    FISSIDENTACEAE. 

the  bifarious  arrangement  of  the  leaves,  and  especially  to  the 
curious  sheathing  laminae,  so  characteristic  of  the  Fissiclentaceae. 
Many  theories  have  been  advanced  to  account  for  the  conduplica- 
tion,  and  if  the  one  that  regards  it  as  being  originally  a  stipule 
that  has  become  adnate  to  the  nerve  by  one  of  its  margins  is 
the  correct  theory  it  certainly  opens  up  a  very  interesting  vista 
of  evolution. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII. ,  No.    77,  November  1915. 


585 


FURTHER    NOTES   ON   THE   CULTIVATION   OF 
PLASMODIA    OF    BADHAMIA    UTRICULARIS. 

By  A.  E.  Hilton. 
{Read  May  25th,   1915.) 

A  year  ago  I  called  your  attention  to  a  method  of  cultivating 
plasmodia  of  Badhamia  utricularis  on  bread,  with  occasional  ap- 
plications of  a  solution  of  ammonium  phosphate  and  cane  sugar  ; 
and  my  paper  on  the  subject  appears  in  the  Journal  for  November 
last.  In  the  discussion  which  followed  the  reading  of  the  paper 
two  points  were  raised  which  I  could  not  reply  to  without  further 
investigation. 

One  of  these  was  an  inquiry  by  our  Secretary  as  to  whether 
plasmodia  of  this  particular  species  of  Mycetozoa  can  be  obtained 
by  cultivation  of  spores  ;  the  answer  to  which  is,  that  it  is 
possible,  but  not  always  easy.  In  the  Journal  of  Botany  for 
January  1901  there  is  an  account  of  an  experiment  on  the  point, 
made  by  the  late  Mr.  Arthur  Lister,  which  ended  successfully 
after  difficulties  by  the  way  had  been  overcome.  In  that  experi- 
ment spores  of  B.  utricularis  were  moistened  with  boiled  water, 
and  spread  on  slices  of  scalded  fungus  (Stereum).  In  six  weeks' 
time,  after  various  vicissitudes,  minute  plasmodia  were  seen 
under  a  microscope  with  a  2/5th-in.  objective,  and  in  another 
fortnight  or  so  a  larger  plasmodium  was  obtained,  which  after- 
wards grew  to  a  considerable  size,  part  being  dried  off  into 
sclerotium  for  subsequent  use,  and  the  remainder  forming 
sporangia.  It  is  to  be  noticed  that  in  using  Stereum  Mr.  Lister 
relied  upon  natural  rather  than  artificial  food,  the  scalding  of 
the  fungus  being  no  doubt  for  the  purpose  of  destroying  any 
organisms  likely  to  upset  the  experiment. 

The  other  question  was  raised  by  our  President,  who  inquired 
whether  plasmodia  fed  by  the  artificial  method  introduced  by 
me  could  form  sporangia.  This  point  was  clearly  of  import- 
ance, involving  as  it  did  the  crucial  question  as  to  whether,  and 
to  what  extent,  such  feeding  affected  the  specific  integrity  of 


586         A.    E.    HILTON    ON    THE    CULTIVATION    OF   PLASMODIA. 

the  fundamental  protoplasm.  Again  I  found  that  the  answer 
to  the  question  was  in  the  affirmative,  but  with  certain  reserva- 
tions. On  February  19th  last  a  plasmodium  of  B.  utricularis- 
was  started  by  reviving  a  fragment  of  sclerotium,  and  this  I 
treated,  throughout  the  whole  course  of  its  development,  with 
nothing  but  bread  and  water,  and  the  chemical  solution,  in- 
cluding calcium  phosphate,  which  I  added  at  Mr.  Grundy's, 
suggestion,  with  a  view  to  supplying  the  lime  usually  found  in 
the  sporangia  of  Mycetozoa  classified  as  Calcarineae.  For  some 
weeks,  owing  to  low  temperatures,  growth  was  slow,  but  on  the 
weather  becoming  warmer,  it  increased  considerably,  and  finally 
on  May  5th,  when  the  atmosphere  became  close,  with  a  thunder- 
storm impending,  the  plasmodium  changed  into  a  quantity  of 
sporangia. 

There  are,  however,  striking  differences  between  these  spor- 
angia and  those  produced  in  natural  conditions.  The  shape  is 
similar,  but  instead  of  being  of  the  usual  cinereous  hue,  they  are 
mostly  a  dull  purple-black ;  others  being  of  a  cinnamon-brown 
colour,  and  some  of  a  pale  biscuit  tint.  All  are  sprinkled  with 
white  crystalline  particles.  The  sporangium  walls,  usually 
very  thin  and  fragile,  are  hard,  thick,  and  chippy ;  and  there  is 
no  distinguishable  capillitium.  Stranger  still,  the  sporangia 
are  only  about  half  the  ordinary  diameter ;  in  other  words, 
about  one- eighth  of  the  usual  size.  The  spores,  generally  bright 
brown  and  spinulose,  are  smooth  and  almost  colourless  ;  but 
they  are  of  the  usual  dimensions,  if  not,  on  the  average,  slightly 
larger,  and  in  other  respects  appear  to  be  perfectly  normal. 

The  characters  on  which  the  classification  is  based  are  thus 
altered  in  nearly  every  particular ;  the  only  permanent  feature, 
if  there  is  one,  being  the  specific  spore-plasm.  The  result  shows 
what  remarkable  powers  of  adaptation  the  plasm  possesses, 
how  precarious  the  present  basis  of  classification  really  is,  and 
how  impossible  it  is  to  define  a  species  without  a  deeper  know- 
ledge than  we  yet  possess  of  the  specific  character  of  the  plasm 
on  which  all  the  activities  of  physical  life  depend. 


Journ.  Quckett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.    77,  November  1915 


587 


HYDRODICTYON  RETiCULATUM. 

By  James  Burton. 

(Read  May  2oth,   1915.) 

Last  autumn  I  had  the  good  fortune  to  obtain  the  freshwater 
alga  known  as  the  Water-net,  Hydrodictyon  reticulatum,  or 
utriculatum,  for  both  names  are  used. 

It  occurred  in  immense  quantity  in  the  lake  in  Kew  Gardens 
and  was  brought  to  my  notice  by  Mr.  Traviss,  who  at  the  "Gossip" 
meeting  in  September  told  me  there  was  a  plant  in  great  amount 
in  the  lake  at  Kew,  and  that  it  was  like  one  of  those  loofahs 
used  in  baths — it  seemed  to  me  a  capital  description,  and  I  at 
once  realised  that  it  was  Hydrodictyon,  and  visited  the  scene 
next  day.  Prof.  West  says  it  is  a  very  rare  plant  in  Britain,  but 
several  authors  say  it  is  found  fairly  frequently  in  the  south 
and  south-east  of  England.  I  do  not  know  of  it  having  been 
found  at  any  of  our  excursions,  and  though  probably  known 
by  name  to  many,  it  is  most  likely  that  few  have  seen  it.  I  have 
a  page,  evidently  part  of  an  article,  in  Dr.  Cooke's  handwriting 
which  gives  some  information  about  it.  He  savs :  "  The 
Water-net  is  one  of  the  earliest  enumerated  of  the  Freshwater 
Algae  in  Britain.  Its  characteristic  form  enables  figures  to  be 
instantly  recognised,  and  thus  we  are  without  doubt  able  to 
assert  its  presence  in  1691,  when  it  was  figured  in  Plukenet's 
Alma  Gestum  (PL  2-1,  f.  2)  and  again  by  Bobart  in  the  3rd  vol* 
of  Morison's  Hortus  Oxoniensis  in  1699.  Ray  includes  it  in  his 
"  Synopsis  "  in  1724  as  Conferva  reticulata,  and  says  that  it  was 
found  at  that  time  in  ditches,  about  Westminster  and  Hounslow." 
Dr.  Cooke  then  gives  a  number  of  instances  in  which  it  is  referred 
to  by  various  writers,  including  Hassall  in  1845.  He  then  says  : 
,;  Recent  localities  have  not  been  recorded,  in  fact  it  is  very 
desirable  that  we  should  know  the  present  stations  of  such  an 
easily  recognised  plant,  which  this  year  appeared  in  such  quan- 
tities in  a  small  pond  in  the  pleasure  ground  at  Kew  Gardens 


588  JAMES    BURTON    ON   HYDRODICTYON    RETICVLATUM. 

at  the  end  of  June,  and  scarce  a  fragment  to  be  seen  in  the 
middle  of  July."  Unfortunately  there  my  page  comes  to  an 
abrupt  end,  but  as  there  are  several  interesting  points  about 
this  alga,  it  may  be  worth  while  bringing  them  to  the  notice  of 
the  Club. 

Owing  to  various  characteristics  which  are  not  found  in  any 
other  alga,  the  genus  Hydrodictyon  has  a  sub-family  to  itself 
and  there  is  only  one  species.  It  consists  of  a  saccate,  net-like 
object  which  ranges  in  size  from  very  small,  almost  microscopic 
dimensions  up  to  a  length  of  several  inches,  four,  six  and  even 
more.  The  cells  of  which  the  net  is  formed  also  vary  very  much 
in  size  ;  in  the  young  ones  they  are  quite  minute,  when  first 
recognisable  from  8  to  10  ft  in  diameter  only,  but  enlarge  so 
much  in  growth  as  sometimes  to  reach  a  length  of  1  cm.,  say 
two-fifths  of  an  inch.  The  cells  are  approximately  cylindrical 
in  shape  and  are  arranged  with  their  ends  in  contact,  usually  three 
meeting  at  such  an  angle  as  to  form  typically  hexagonal  meshes, 
but  meshes  with  fewer  or  more  boundary  cells  are- not  uncommon. 
They  have  a  somewhat  thick  cell-wall,  and  inside  a  layer  of 
protoplasm,  in  which  the  green  chlorophyll  is  diffused,  not 
collected  into  definite  chloroplasts  as  is  usual  in  algae. 

The  centre  is  filled  with  cell-sap.  There  are  very  numerous 
and  quite  typical  pyrenoids  in  the  protoplasm,  each  consisting 
of  a  central  body,  with  a  layer  of  starch  grains  on  the  outside  ; 
these  may  be  considered  reserve  food  material.  At  the  com- 
mencement of  reproduction  they  disappear,  and  are  obviously 
used  up  during  the  process.  There  is  also  a  quantity  of  fine 
starch  grains  in  the  protoplasm,  these  being  used  for  the  purposes 
of  life  and  growth.     Many  nuclei  are  present  in  each  cell. 

The  first  point  to  notice  is  that  the  organism  as  a  whole  is 
what  is  known  as  a  coenobium ;  it  is,  perhaps  something  more 
than  what  is  known  as  a  colony,  because  the  individual  cells  are 
actually  attached  to  one  another,  and  form  an  association, 
but  certainly  they  are  not  greatly  dependent  on  each  other. 
Each  component  cell  is  an  individual,  and  carries  on  its  living 
functions  independently  ;  for  its  own  benefit  solely  it  assimilates, 
respires  and  reproduces,  and  were  it  separated  from  its  fellows 
would  still  be  able  to  exist.  We  might  then  be  inclined  to 
inquire  what  advantage  the  plant  gains  from  the  association 
of  so  many  units.     One  advantage  is,  that  if  the  composing  cells 


JAMES    BURTON    OX  HYDRODICTYOX    RETICULATUM.  589 

were  separate,  and  sank  to  the  bottom  of  the  water,  the}7  would 
be  liable  to  become  overwhelmed  in  the  mud  and  debris,  while 
in  their  present  condition  they  would  rest  on  the  bottom  without 
danger  of  being  covered  up.  It  may  also  be  noticed  that  an 
organism  formed  like  the  water-net.  when  it  is  in  active  life 
under  the  influence  of  warmth  and  light,  excretes  gas,  and  forms 
bubbles,  which  are  entangled  in  the  meshes  and  float  the  whole 
colony  to  the  surface  where  it  obtains  better  light  and  purer 
water.  Another  advantage  may  be  that  the  separate  cells, 
being  for  a  time  very  small,  would  be  liable  to  be  taken  as  food 
by  various  small  aquatic  animals,  a  fate  to  which  they  are 
much  less  subject  when  combined  into  a  larger  body.  Many 
of  the  filamentous  algae  not  usually  looked  upon  as  composed 
of  individuals,  as  coenobia  in  fact,  are  so  in  reality.  This  is  the 
case,  for  instance,  with  the  well-known  Spirogyra ;  here  each 
cell  of  the  filament  if  separated  would  be  able  to  carry  on  its 
vital  functions,  and  probably  the  chief  advantage  it  gains  from 
its  form  is  something  of  the  kind  already  mentioned. 

But  this  brings  me  to  the  next  point  of  interest  in  the  water-net. 
In  Spirogyra  and  almost  all  other  freshwater  algae,  multiplication 
very  largely  takes  place — in  many  species  there  is  no  other 
method  of  propagation — by  means  of  what  we  may  call  vegeta- 
tive reproduction.  A  cell  grows  till  it  reaches  its  maximum 
size,  a  wall  is  then  formed  across  it  and  the  one  large  mature  cell 
becomes  two  smaller  young  ones  which  gradually  grow,  and  the 
process  is  repeated.  Now  in  Hydrodictyon  there  is  no  division 
of  a  cell.  You  may  examine  any  number  of  plants,  each  con- 
sisting of  perhaps  thousands  of  cells,  and  you  will  never  find  one 
undergoing  cell-division.  The  cell  begins  quite  small  and  grows 
till  it  reaches  what  is  a  very  large  size  for  such  an  organism, 
but  it  never  gives  rise  in  this  way  to  another.  From  this  a 
singular  result  arises.  The  net  is  born,  as  we  may  say,  with  a 
given  number  of  cells,  and  through  its  life  it  consists  of  only  the 
same  number  and  indeed  of  the  identical  ones  which  it  had 
originally.  If  owing  to  injury  a  part  of  the  net  is  destroyed,  it 
is  not  replaced,  the  deficiency  cannot  be  made  good. 

Another  unique  fact  is  the  method  of  reproduction ;  no  other 
alga  has  the  same  in  detail.  In  the  non-sexual  method — which 
is,  I  think,  the  most  usual  and  is  indeed  the  only  kind  of  which 
I  have  had  actual  experience — a  small  complete  net  consisting, 


590  JAMES    BURTON    ON  HYDRODICTYON  RETICVLATUM. 

it  may  be,  of  some  thousands  of  cells,  is  formed  inside  each  of  the 
members  of  the  original  net,  which  is  reproducing.  The  process 
takes  place  in  this  way.  The  pyrenoids  disappear  and  the 
protoplasm  collects  round  each  of  the  numerous  nuclei,  these 
then  divide  repeatedly,  until  the  whole  becomes  an  enormous 
number  of  spherical  zoogonidia ;  there  may  be  from  7,000  to 
20,000  of  them  in  a  single  cell.  In  this  they  "  swarm,"  as  it  is 
called,  i.e.  they  have  a  tremulous  motion,  not  moving  from 
place  to  place  to  any  extent,  but  just  vibrating.  There  is  some 
uncertainty  as  to  whether  the  gonidia  have  cilia  ;  one  account 
says  they  have  four,  most  say  two,  and  one  account — I  think 
it  is  in  Kerner — says  they  are  not  completely  separated  from 
one  another,  but  remain  attached  by  a  thread  of  protoplasm. 
I  do  not  think  this  is  correct  and  believe  they  are  actually 
separate  for  a  time,  they  then  become  oval  instead  of  spherical 
and  attach  themselves  to  one  another  by  the  ends,  and  gradually 
in  each  mother-cell  a  complete  young  one  is  thus  formed. 

In  the  meantime  the  mother-cell  wall  gelatinises,  and  this  goes 
on  so  that  by  the  time  the  young  net  is  complete  there  is  scarcely 
any  of  the  wall  remaining,  and  soon  it  is  entirely  diffused  and 
the  young  one  is  set  free.  Some  of  the  books  tell  us  that  a  slit 
is  formed  in  the  mother-cell  and  the  young  net  escapes  through 
that,  but  I  have  not  seen  this  occur,  and  think  that  the  des- 
cription applies  to  another  circumstance — namely,  the  sexual 
reproduction.  This  I  have  not  observed,  but  stated  shortly 
the  method  is  as  follows  :  A  much  larger  number  of  minute 
reproductive  bodies  than  in  the  previous  case  is  formed.  From 
30,000  to  100,000  of  them  arise  in  the  parent  cell ;  each  of  these 
gametes  has  either  two  or  four  cilia.  They  issue  from  the 
parent  cell  through  a  slit  in  the  wall,  enclosed  in  a  vesicle  formed 
from  the  inner  layer  of  the  cell,  and,  becoming  free  in  the  water, 
conjugate  in  pairs.  The  resulting  zygospore  sinks  to  the  bottom. 
It  may  germinate  at  once,  but  usually  divides  into  two  or  four 
parts  which  become  resting  spores — they  are  known  from  their 
shape  as  polyhedra  ;  after  some  months  they  give  rise  indirectly 
to  small  nets,  which  then  give  rise  to  larger  ones  of  the  usual 
character.  It  may  be  noticed  that  there  is  no  true  sexuality 
in  the  cells — or  individuals — of  which  the  net  is  formed.  Any 
cell  may  give  rise  to  either  sexual  or  non-sexual  reproduction 
according  to  circumstances.     Klebs   (I  think  it  is)   has  stated 


JAMES    BURTON    OX   HYDRODICTYON  RETICCLATU.V.  591 

that  non-sexual  reproduction  occurs  when  the  water  is  clear 
and  there  is  abundance  of  chemical  food  material  present  with 
appropriate  temperature  and  light — in  fact  with  favourable 
vegetative  conditions — while  under  less  favourable  conditions, 
and  with  the  presence  of  organic  matter,  decaying  plants  and  so 
on,  in  the  water,  there  is  a  tendency  for  sexual  reproduction  to 
take  place.  And  he  states  that  either  condition  may  be  readily 
brought  about  at  will,  with  plants  grown  under  observation. 

Perhaps  not  the  least  interesting  fact  about  Hydrodictyon  is 
the  manner  of  its  occasional  appearances.     After  being  plentiful 
on  one  occasion  it  will  totally  disappear,  and  for  perhaps  several 
years  nothing  will  be  seen  of  it.      Then  again,  owing  to  no 
particular  cause  which  is  understood,  it  has  another  outbreak, 
and  the  water  from  which  it  has  been  absent  for  long  is  again 
filled  with  it.     These  outbreaks  are  known  in  some  parts  as  the 
"  breaking  of  the  meres,"  and  by  other  similar  terms.     I  knew 
that  in   times  past  Hydrodictyon  frequently  appeared  in  the 
lake  in  Kew  Gardens  and  for  many  years — more  than  thirty, 
I  believe — looked  out  for  it  in  vain.     During  all  this  time  I  only 
found  one  very  small  and  unsatisfactory  specimen.     Then  last 
autumn  a  tremendous  outbreak  occurred,  the  water  was  so  full 
of  it  that  at  the  lee  end  of  the  lake  the  Hydrodictyon  was  massed 
together  to  such  an  extent  that  it  was  impossible  to  get  good 
examples.     Two  boats  were  on  the  water,  with  men  gathering 
it  in  with  rakes  and  piling  it  in  heaps  on  the  shore.     In  rather 
less  than  four  weeks  I  again  visited  Kew,  and  though  diligent 
search  at  every  part  of  the  lake  was  made,  not  a  single  specimen 
could  be   found.     Prof.  West  in  speaking  of  this  phenomenon 
in  regard  to  various  other  algae  says  ';  they  usually  consist  of 
species  that  are  normally  present  in  the  waters."     But  that  can 
hardly  be  said  in  this  case  ;  normally  it  is  impossible  to  find  an 
example  of  Hydrodictyon  in  the  lake  at  Kew. 

Personally  I  cannot  suggest  any  better  explanation  of  the 
cause  of  the  phenomenon  than  I  gave  once  before.  Speaking 
of  a  similar  outbreak  of  another  alga  it  was  said  :  "Of  course  in 
some  form  they  must  always  be  present  in  the  places  in  which 
they  occasionally  appear  so  abundantly ;  but  the  causes  which 
enable  them  to  multiply  in  this  manner  seem  to  be  unknown. 
It  cannot  be  a  seasonal  increase  alone,  such  as  we  have  in  flower- 
ing plants,   which   at    the    proper    time  develop  and   then  die 


592  JAMES    BURTON    ON   HYDRODICTYOX    RETICULATUM. 

away.  In  that  case  the  '  breaking  of  the  meres  '  would  be  an 
annual  occurrence,  or  nearly  so,  with  more  tendency  to  regularity 
than  it  seems  to  have.  Clearly  there  must  be  some  simultaneous 
occurrence  of  several  favourable  circumstances  which  does  not 
frequently  arise  :  possibly  some  special  type  of  weather  and 
some  narrow  range  of  temperature  at  a  particular  season  would 
be  factors  in  the  required  conditions." 


Jottrn.  Quekell  Microscopical  Club,  Ser.    2,  Vol.  XII.,  No.  77,  November  1915. 


593 


VARIOUS    INSECT   STRUCTURES. 

By  Edward  M.  Nelson,  F.R.M.S. 

{Read  May  25th,   1915.) 

The  wing  of  Agrion  pulchellum  (Neuroptera)  is  not  only  a  wonder- 
ful, but  a  particularly  interesting  microscopical  object.  The 
membrane,  which  in  life  reflects  beautiful  colours,  is  double, 
each  part  being  bordered  by  a  stout  rim  edged  with  formidable 
saw-like  teeth.  The  surface  of  the  wing  is  divided  into  com- 
partments by  nervures  which  are  peculiar  ;  for  the  transverse 
bars,  as  well  as  four  of  the  longitudinal  bars,  have  on  one  edge 
thorns  just  like  those  on  a  sloe-bush,  and  on  the  other  edge 
saw-like  teeth  ;  there  are  three  other  longitudinal  ribs,  which 
have  saw-like  teeth  on  one  edge  and  very  fine  teeth  on  the  other, 
but  no  thorns. 

This  beautiful  microscopical  object  forms  an  excellent  test  for 
low  powers,  "  loups  "  or  simple  microscopes. 

At  one  part  on  the  edge  of  the  wing  there  is  a  dark-coloured 
compartment,  inappropriately  called  the  "  stigma."  This  really 
is  a  pocket,  the  two  membranes  being  separated  from  one  another 
at  this  point  by  some  brown  cellular  tissue,  the  saw-edged 
borders  of  the  membranes  being  kept  apart,  thus  forming  an 
opening.  Obviously,  then,  the  "  stigma '  is  an  apparatus  for 
producing  a  sound,  much  in  the  same  way  as  the  "  bull  roarer  " 
of  our  childhood.  The  "  stigma  '  can  be  seen  readily  by  the 
naked  eye,  as  it  measures  1*1  mm.  x  0'5  mm. 

If  we  replace  the  low  power  by  a  1/2  inch,  a  careful  examina- 
tion of  the  border  of  the  wing  reveals  a  delicate  hair  between 
the  teeth  of  the  saw  (fig.  1). 

These  hairs  are  minute,  the  largest  one  found  measured  only 
23  fx  in  length  and  2  fx  in  breadth ;  but  on  other  species  of  Dragon- 
flies  they  are  larger  and  more  easy  to  demonstrate.  These  hairs 
spring  out  of  circular  rings,  after  the  manner  of  most  hairs  on 
insects,  and  not  like  the  small  ones  on  the  membrane  of  the 
blow-fly's  tongue,  which  have  no  rings.     While  on  this  subject  of 

Journ.  Q.  M.  C,  Series  II.— No.  77.  33 


594       EDWARD    M.    NELSON    ON   VARIOUS    INSECT   STRUCTURES. 

insects  hairs,  a  careful  examination  of  the  small  hairs  upon  the 
wing  of  a  wasp  will  show  that  they  are  twisted  like  the  tusk  of 
a  narwhal  (fig.  6). 

The  hairs  on  a  bee's  wing  are  somewhat  similar,  but  not  so 
much  twisted,  while  they  have  no  ring.  Those  on  the  wing  of 
a  saw-fly  (Tenthredo)  issue  from  a  boss.  The  hairs  on  the 
ovipositor  of  Phalangia  are  more  interesting.  This  ovipositor 
has  some  thirty  or  forty  white  and  brown  transverse  stripes  ; 
the  hairs  upon  it  are  of  the  ordinary  kind  with  a  ringed  base, 


7*/. 


4- 


except  those  upon  the  two  last  terminal  stripes,  where  the  hairs 
are  larger  and  the  ringed  base  is  ornamented  with  a  circle  of 
very  minute  hairs  ;  the  hair  itself  is  tubular  and  has  a  fila- 
mentous end.  At  the  side  of  these  hairs  there  is  a  sort  of  minute 
prong,  which  might  be  thought  a  hook,  but  is,  I  think,  a  cut  or 
opening  in  the  side  of  the  hair  (fig.  4,  termination  of  hair  not 
drawn).  At  the  end  of  each  of  the  two  lobes  of  the  ovipositor 
is  a  small  boss  covered  with  small  hairs.  These  hairs  have  no 
ring  bases  and  are  blunt-ended,  probably  open  at  the  top ;  but 
they  have  internal  ring  (not  spiral)  structure  somewhat  like  an 


EDWARD    M.    XELSOX    ON    VARIOUS    INSECT   STRUCTURES.       595 

artery  (fig.  5) .  A  1/4 th  inch  will  be  necessary  to  demonstrate  these 
structures.  The  saw  on  the  wing  of  Agrion  is  a  comparatively 
bold  structure,  but  if  we  examine  the  mandibles  of  a  gad-fly 
(Tabanus  bovinus)  we  shall  find  upon  one  edge  the  most  wonderful 
saw  in  the  world,  having  ten  to  sixteen  thousand  teeth  per  inch 
on  it,  while  the  other  edge  is  the  keenest  blade  in  existence 
(fig.  7).  As  a  point  of  "  microscopy  "  these  teeth  on  the  saw  on  the 
the  lancets  or  mandibles  of  this  insect  form  the  most  delicate 
optical  test  I  know.  This  is  a  matter  of  some  importance,  as 
Podura  test-scales  are  now  not  to  be  had — for,  sad  to  say,  one 
may  pay  20s.  for  a  slide  of  Podura  scales  and  not  find  a  single 
test-scale  upon  it !  If  any  member  of  the  Club  has  an  objective 
that  will  show  these  saw-like  teeth  with  a  large  or  full  cone  he 
should  take  great  care  of  it,  as  it  may  be  some  time  before  he 
finds  another  that  will  do  so.  A  1 J  inch  *  that  will  demon- 
strate these  teeth  at  the  point  of  the  mandible  with  axial 
illumination  must  be  a  good  lens.  This  test,  however,  is  not 
confined  to  low  powers,  for  high  powers  such  as  a  l/4th  or 
a  l/6th  that  will  show  the  teeth  with  a  large  working  aperture 
cannot  have  much  wrong  with  them.  *As  the  aperture  of  the 
substage  condenser  is  opened  a  point  will  be  found  when,  owing 
to  spherical  aberration  in  the  objective,  the  image  of  the  teeth 
will  vanish  suddenly.  This  test  rivals  in  sensitiveness  all  others 
with  which  I  am  acquainted,  and  it  is  scarcely  necessary  to  add 
that  a  precise  adjustment  of  tube  length  is  necessary ;  but  it  is 
important  to  bear  in  mind  that  with  a  small  or  moderate  sized 
cone  it  is  no  test  at  all. 

The  teeth  are  coarser  at  the  point,  where  they  count  10,000 
per  inch,  and  finer  at  the  base  of  the  mandible,  where  they 
count  16,000  per  inch.  Those  on  the  mandible  of  Haematopoda 
fluvialis  are  still  finer  and  count  from  15,600  to  19,200  per  inch. 
The  stout  hairs  on  the  palpi  of  this  insect  issue  from  a  delicate 
cup.  The  hairs  on  the  wing  of  Tricho'pteryx  atomaria  have 
secondary  hairs  on  them  ;  a  secondary  hair  measured  in  length 
1*1  /./,  thickness  0*18  /a  =  yiiVoo"  mch.  This  beautiful  micro- 
scopical object  cannot  be  seen  with  an  objective  of  less  than 
0'58  N.A.  These  few  instances  are  mentioned  to  show  that 
a   critical   examination   of  the   hairs   of    insects   is   not   only  a 

*  Some  H  inches  are  engraved  2  inches;  such  lenses  should  also 
show  them. 


596       EDWARD    M.    NELSON    ON    VARIOUS   INSECT    STRUCTURES. 

useful,  but  also  a  fascinating  branch  of  microscopical  study. 
We  will  now  pass  on  for  a  moment  to  the  Vespa  crabro,  or 
hornet.  If  its  sting  be  examined  with  a  2/3rd  inch  objective 
the  barbs,  A,  fig.  2,  will  be  seen ;  B  is  a  tube,  and  C  a  razor  blade. 
Fig.  3  shows  the  sting  in  section.  The  fine  tubules,  three  below 
the  last  barb  and  one  below  each  of  the  others,  will  be  seen.  The 
breadth  of  the  sting  in  fig.  2  is  110  fx,  the  width  of  the  razor  blade 
33  fx,  the  length  of  a  barb  17  /x,  the  length  of  a  tubule  25  //,,  and  its 
width  4*2  fx.  If  the  sting  happens  to  be  well  placed  the  exit 
pore  of  a  tubule  may  be  caught.  It  is  probable  that  these  stings 
are  homologous  with  the  saws  in  the  ovipositors  of  insects. 
Instead  of  barbs  there  are  bold  saw-like  teeth,  which,  unlike 
those  in  a  carpenter's  saw,  go  round  the  side  of  the  saw — the 
holes  for  the  emission  of  lubricating  or  poisonous  fluids  are 
numerous  and  much  easier  noted  than  those  on  the  sting  of  a 
hornet.     The  ovipositor  of  a  dragon-fly  is  a  good  example. 

In  conclusion,  I  would  draw  your  attention  to  the  pygidium 
of  a  flea.  If  the  right-  and  left-hand  edges  be  examined  a  hole  will 
be  found ;  this  is  an  Eustachian  tube.  The  apparatus  corresponds 
to  the  drum  of  an  ear,  and  must  like  it  have  an  air  passage  to 
equalise  the  pressure  on  either  side.  Now  look  at  the  base  of 
the  haltere  in  a  blow-fly,  where  a  similar  tube  will  be  easily  seen. 


Joum.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  Nc.  77,  November  1913. 


597 


THE  DETERMINATION  OF  MINERALS  UNDER  THE 
MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL 
CHARACTERS.* 

By  J.  W.  Evans,  D.Sc,  LL.B.  (London), 

OF   THE    IMPERIAL   COLLEGE    OF   SCIENCE    AND   TECHNOLOGY, 
AND    BIRKBECK    COLLEGE,    UNIVERSITY    OF    LONDON. 

(Read  June  22nd,   1915.) 

Communicated  by  the  Hon.  Editor. 

Plates  35-37. 

A  petrological  microscope  is  not  merely  employed  for  the 
study  of  details  too  small  to  be  seen  by  the  unaided  eye,  it  is 
also  an  instrument  for  the  investigation  of  the  optical  properties 
of  minerals,  by  means  of  which  they  may  be  distinguished 
from  one  another. 

Kotation  of  Nicols  or  Stage. — For  this  purpose  the  microscope 
must  be  so  constructed  that  the  minerals  can  be  examined 
between  crossed  nicols.  A  Nicol's  prism  or  nicol  permits  only 
light  vibrating  in  a  particular  direction  to  pass.  Two  nicols 
are  said  to  be  crossed  when  these  directions  of  vibration  are  at 
right  angles  to  each  other.  It  is  also  necessary  that  either  the 
stage  or  the  nicols  shall  be  capable  of  rotation  round  the  micro- 
scope axis.  For  many  reasons  the  rotation  of  the  nicols,  while 
the  stage  remains  stationary,  is  to  be  preferred ;  and  when  an 
immersion  lens  is  employed  with  loose  material,  it  is  essential 
that  there  should  be  no  relative  movement  between  the  stage 
and  objective.  The  mechanical  difficulties  of  construction  in 
instruments  of  this  type  add,  however,  considerably  to  the 
expense,  with  the  result  that  in  the  majority  of  petrological 
microscopes  in  use  the  nicols  are  fixed,  while  the  stage  rotates. 
I  have,  accordingly,  assumed  throughout  that  such  an  instru- 

*  A  brief  communication  to  the  Geologists'  Association  on  similar  lines 
was  made  by  the  author  in  1909  (see  Proc.  Geol.  Assoc,  vol.  xxi.,  1909, 
pp.  79-94).  The  Quekett  Microscopical  Club  is  indebted  to  the 
Geologists'  Association  for  their  courteous  permission  to  use  the  blocks 
illustrating  this  paper. 


598     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

ment  is  employed.  At  the  same  time  tlie  complication  of  the 
phenomena  caused  by  the  rotation  of  the  object  renders  a 
systematic  procedure,  such  as  I  shall  describe,  very  desirable,  if 
mistakes  are  to  be  avoided. 

Centring. — In  such  an  instrument  an  arrangement  for  centring, 
by  which  the  axis  of  the  microscope  can  be  adjusted  so  that  it 
may  pass  through  the  centre  of  the  stage,  is  absolutely  necessary. 
The  centring  may  be  carried  out  by  placing  a  rock-slice  in  focus 
under  the  microscope,  noticing  the  point  round  which  the  object 
seems  to  rotate,  and  bringing  this  to  the  centre  of  the  field  by 
means  of  the  centring  screws. 

Nose-fiece. — The  mechanism  for  centring  should  be  applied  to 
the  nose-piece  and  not  to  the  stage,  since  it  is  the  former  which 
is  most  liable  to  be  displaced,  especially  if  a  double  or  triple 
nose-piece  for  interchanging  objectives  be  employed.  The  use 
of  a  clutch,  first  employed,  I  believe,  by  Nachet,  by  which 
objectives  can  be  rapidly  attached  or  removed,  is  preferable. 
Kecently  a  lateral  sliding  arrangement  has  been  introduced,  but 
I  do  not  think  that  it  possesses  any  points  of  superiority  over 
the  clutch. 

Movements  of  One  Nicol. — One  or  both  nicols  should  be 
capable  of  separate  rotation,  and  one  at  least  should  be  capable 
of  being  rapidly  thrown  out  of  the  course  of  the  light  so  that 
the  observation  may  be  made  with  one  nicol  only.  The  nicol 
that  remains  in  position  should  be  so  placed  that  it  allows  light 
vibrating  right  and  left  to  pass,  for  with  the  usual  disposition 
of  the  mirror  the  light  reflected  from  it  is  polarised  so  that 
more  of  it  already  vibrates  in  this  than  in  other  directions. 
There  is  consequently  an  appreciable  saving  of  light  with  this 
position  of  the  nicol.* 

It  is  usual  to  remove  the  upper  nicol  or  analyser,  but  F.  E. 
Wright  recommends  the  removal  of  the  lower  nicol  or  polariser. 
This  has  the  advantage  that  the  field  is  not  affected  in  focus 
or  position,  when  the  nicol  is  moved  in  or  taken  out. 

*  To  ascertain  in  what  direction  light  traversing  a  nicol  vibrates, 
the  nicol  should  be  inserted  alone  and  a  rock-slice  containing  biotite 
flakes  showing  strong  pleochroism  placed  on  the  stage  and  rotated 
till  a  flake  is  in  the  position  of  maximum  darkness.  The  direction 
of  the  cleavage  of  this  flake  will  then  be  parallel  to  that  of  the  vibration 
of  the  nicol. 


THE    MICROSCOPE    BY  MEANS    OF    THEIR  OPTICAL  CHARACTERS.    599 

The  upper  nicol  usually  slides  in  and  out  of  the  lower  part 
of  the  tube  above  the  objective.  This  has  the  advantage  of 
not  obstructing  the  field,  but  there  are  two  objections  to  this 
plan.  In  the  first  place  the  nicol  cannot,  as  usually  constructed, 
be  rotated,  and  secondly,  it  does  not  allow  of  the  insertion  of 
a  quartz  wedge  in  focus.  For  this  reason  the  upper  nicol  is 
sometimes  placed  above  the  eye- piece.  In  this  case  it  should 
be  thrown  in  or  out  by  means  of  a  hinge.  The  common 
arrangement  by  which  it  is  removed  altogether  results  in  loss 
of  time  in  adjustment  when  it  is  replaced.  The  nicol  that 
rotates  should  be  provided  with  catches  or  ""clicks"  to  arrest 
its  movement  in  the  crossed  position,  and  in  that  at  right 
angles  to  it,  in  which  its  direction  of  vibration  is  parallel  to 
that  of  the  other  nicol. 

Cross  Wires. — The  cross  wires  will  be  parallel  to  the  directions 
of  vibration  of  light  traversing  the  nicols  respectively  when  in 
their  normal  position. 

The  cross  wires  should  not  be  spider  lines,  which  are  easily 
broken  by  the  insertion  of  the  quartz  wedge  or  other  accessories, 
but  should  be  ruled  on  a  glass  plate.  As  this  is  apt  to  get 
covered  with  dust,  the  eye-piece  should  be  made  to  screw  apart 
immediately  above  the  plate  so  that  it  may  be  easily  cleaned. 

Slots. — The  microscope  should  be  provided  with  one  or  more 
slots  for  the  insertion  of  various  accessories.  In  this  country 
slots  are  placed  diagonally  to  the  cross  wires.  On  the  Continent, 
however,  they  are  sometimes  right  and  left,  and  accessories 
connected  with  polarization  effects,  such  as  quartz  wedges, 
gypsum  plate,  or  mica  steps,  must  be  constructed  accordingly. 
This  is  a  matter  that  requires  attention  in  buying  and  working 
with  foreign  microscopes.  The  slot  is  usually  placed  immediately 
above  the  objective.  Wright,  however,  prefers  to  have  it  below  the 
stage  (but  naturally  above  the  lower  nicol),  so  that  the  insertion 
of  a  plate  or  wedge,  like  that  of  the  lower  nicol  referred  to  above, 
does  not  affect  the  field.  Another  course  is  to  have  the  slot 
at  the  focus  of  the  eye- piece,  in  which  case  the  upper  nicol  must 
be  placed  above  the  eye-piece.  This  arrangement  has  the 
advantage  that  a  quartz  wedge,  or  other  accessory,  placed  in 
the  slot  is  in  focus.  The  same  result  can  also  be  obtained 
with  a  slot  below  the  stage,  if  the  condenser  be  placed  in  position 
and  slightly  lowered. 


600      J.    W.    EVANS   ON  THE   DETERMINATION  OF  MINERALS   UNDER 

Means  should  be  provided  to  close  the  slot,  when  not  in  use. 

Fine  Adjustment. — The  fine- adjustment  screw  should  be 
graduated  on  its  circumference  so  as  to  show  the  number  of 
microns  by  which  the  microscope  is  raised  or  depressed.  A 
micron  is  the  thousandth  part  of  a  millimetre  and  is  the  most 
convenient  unit  of  length  for  microscopical  purposes.  A  com- 
plete turn  of  the  screw  will  usually  correspond  to  500  microns, 
and  in  that  case  a  scale  parallel  to  the  axis  should  be  provided, 
divided  into  half  millimetres,  so  that  by  means  of  the  double 
graduation  comparatively  large  movements  may  be  accurately 
measured. 

Illumination. — The  best  illumination  is  that  from  the  sky.  If 
artificial  light  must  be  resorted  to,  a  gas  mantle  provided  with 
a  cylinder  of  ground  or  milk-white  glass,  or  a  small  arc  light 
similarly  treated,  should  be  employed.  If,  however,  the  illumi- 
nation is  very  strong,  the  lower  nicol  may  be  injured  by  over- 
heating. If  there  is  any  danger  of  this,  a  suitable  glass  vessel 
containing  water  may  be  interposed. 

Objectives. — Although  a  1-in.  objective  is  used  for  most  pur- 
poses, a  lower  power  is  convenient  in  the  case  of  rocks  of  coarse 
texture,  while  for  very  fine  structures  and  minute  crystals  and 
inclusions  a  l/4th-in.  or  still  higher  power  must  be  employed. 
I  have  myself  found  a  twelfth  very  useful. 

These  close  objectives  are  also  required  for  the  simultaneous 
examination  of  different  directions  in  a  crystal,  a  subject  I  shall 
deal  with  later. 

Rock-slices. — A  good  rock-slice  should  range  between  twenty 
and  thirty  microns  in  thickness,  but  with  comparatively  large 
transparent  minerals  much  thicker  sections  may  usefully  be  em- 
ployed, while  those  with  fine  structures  or  which  are  comparatively 
opaque  should  be  as  thin  as  they  can  be  made.  It  is  important 
that  a  section  should  be  as  uniform  in  thickness  as  possible, 

It  is  preferable  that  a  rock-slice  intended  for  research  should 
have  no  cover- glass  and  that  its  surface  and  sides  should  be  free 
from  Canada  balsam.  It  may  then  be  covered  in  turn  by  liquids 
with  different  refractive  indices  (see  p.  626)  or  subjected  to 
microchemical  tests. 


THE  MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      601 


The  Object-Image. 

Under  this  heading  I  include  all  observations  in  which  the 
object  itself  appears  in  focus  in  the  field  of  the  microscope. 

Examination  in  Ordinary  Light. — The  crystal  section  should 
be  brought  into  the  centre  of  the  field,  so  that  it  lies  beneath  the 
intersection  of  the  cross  wires,  and  the  stage  rotated  till  the  index 
reading  is  zero.  The  outline  and  any  other  characteristic  features 
should  now  be  traced  or  sketched,  surrounded  by  a  circle  repre- 
senting the  margin  of  the  field,  and  a  scale  of  microns  with  the 
numerical  value  of  the  magnification  added.  The  scale  is  con- 
structed with  the  assistance  of  an  eye-piece  micrometer  calibrated 
from  a  stage  micrometer.  The  position  of  the  cross  wires  is 
shown  by  short  radial  lines  drawn  inwards  from  the  circumfer- 
ence (figs.  1-3).  The  right  end  of  the  right  and  left  cross  wire  is 
marked  with  0°  outside  the  circle,  because  it  is  the  direction  of 
the  vibration  of  the  nicol,  when  one  only  is  inserted,  and  the 
positions  of  the  other  ends  of  the  cross  wires  by  90°,  180°  and 
270°,  in  the  same  cyclical  order  as  the  graduations  on  the 
stage,  which  are  usually  contrary  to  those  of  the  hands  of  a 
watch. 

The  stage  is  now  rotated,  and  as  the  trace  of  a  face,  cleavage 
or  other  rectilineal  marking,  such  as  a  line  (representing  a  plane) 
of  inclusions,  comes  into  a  position  of  parallelism  with  the  right 
and  left  cross  wire,  the  latter  should  be  inserted  in  its  new  position 
in  the  sketch  as  an  interrupted  line  across  the  field,  and  dis- 
tinguished on  its  right  extremity  outside  the  circle  by  the 
index  reading  of  the  stage  (figs.  1-3).  As  each  line  comes  twice 
into  the  right  and  left  position,  it  will  have  readings  at  both 
ends,  which  will  differ  by  180°.  All  these  readings  will  follow 
each  other  in  the  sketch  in  their  cyclical  order. 

Extinctions. — Both  nicols  are  now  inserted  in  the  crossed 
position  and  the  stage  rotated.  If  the  crystal  section  remain 
dark  through  a  complete  rotation,  the  crystal  section  is  either 
isotropic  or  cut  at  right  angles  to  the  optic  axis  of  a  uniaxial 
crystal.  If  it  continue  uniformly  faintly  illuminated,  it  is  at 
right  angles  to  an  optic  axis  of  a  biaxial  crystal.  Usually, 
however,  it  will  be  dark  at  four  points  in  the  rotation  when  the 
directions   of   vibration   of   light  traversing   the   crystal  section 


602     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

are   parallel   to   those   of  the   nicols   and   therefore  to  the  cross 
wires.* 

These  positions  of  darkness  are  known  as  extinctions,  and  they 
are  distant  90°  from  one  another.  If  the  section  is  exactly  at 
right  angles  to  a  plane  of  crystal  symmetry  or  parallel  to  an 
axis  of  crystal  symmetry,  in  which  cases  it  is  at  right  angles  to 
a  plane  of  optical  symmetry,  the  position  of  extinction  will  be 
identical  for  all  colours  and  will  be  characterised  by  complete 
darkness.  At  the  same  time  the  crystal  outline  will  usually 
be  symmetrical  to  the  cross  wires,  which  will  now  indicate  the 
directions  of  vibration,  both  in  the  nicols  and  the  crystal,  for  all 
colours.     In  such  cases,  the  extinction  is  said  to  be  symmetrical. 

If,  on  the  other  hand,  the  section  does  not  occupy  such  a  position 
the  extinction  will  be  different  for  different  colours,  or,  as  it  is 
usually  expressed,  is  dispersed.  Unless  the  dispersion  be  very 
small,  there  will  never  be  complete  darkness  with  white  or  other 
composite  light,  but  it  may  always  be  obtained  by  employing 
monochromatic  light. 

There  is  usually  some  difficulty  in  determining  the  position 
of  maximum  darkness  corresponding  to  the  true  position  of 
extinction,  even  where  there  is  no  dispersion,  or  where  mono- 
chromatic light  is  employed,  and  resort  has  been  had  to  various 
methods  of  obtaining  an  exact  result. 

One  of  the  simplest  of  these  is  to  rotate  the  stage  towards 
the  position  of  extinction  alternately  from  opposite  cyclical 
directions  and  to  note  the  readings  on  each  side  where  the  same 
degree  of  darkness  has  been  obtained.  The  mean  of  several 
pairs  of  careful  observations  will  approximate  closely  to  the 
index  reading  corresponding  to  the  true  position  of  extinction. 

In  another  method,  which  has  been  investigated  in  detail  by 
F.  E.  Wright,  |  the  crystal  is  first  placed  in  the  approximate 
position  of  extinction  obtained  in  the  manner  already  described, 
and  then  one  of  the  nicols  is  rotated  through  a  small  but  definite 
angle  and  the  degree  of  illumination  that  results  is  carefully  noted. 
The  nicol  is  next  rotated  in  the  opposite  direction  through 
exactly  the  same  angle  on  the  other  side  of  its  normal  position. 

*  According  to  one  view  of  the  direction  of  the  vibration  of  light 
in  crystals  this  is  not  strictly  true  ;  it  is,  however,  in  any  case  sufficiently 
accurate  for  practical  purposes. 

t   Am.  Journ.  Sci.,  Series  IV.,  vol.  xxvi.,  1908,  pp.  349-3G8,  379. 


THE    MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      603 

If  the  illumination  in  the  two  cases  be  the  same,  the  supposed 
position  of  extinction  is  correct.  If  not,  the  nicol  is  restored 
to  its  original  position,  and  the  stage  is  rotated  slightly  towards 
the  direction  in  which  the  darkness  was  the  greater.  The 
same  test  is  then  again  applied,  and,  if  necessary,  the  process 
is  repeated,  till  the  rotation  of  one  nicol  through  equal  angles 
in  both  directions  produces  the  same  result. 

The  angle  through  which  the  nicol  must  be  rotated  is  that 
which  will  produce  a  faint  illumination  for  rotation  in  one  direc- 
tion. It  is  usually  between  half  a  degree  and  two  degrees.  As 
a  rule  it  would  be  sufficient  if  a  graduation  were  provided  showing 
a  rotation  of  a  nicol  through  J,  1  and  1J  degrees. 

Where  the  position  of  extinction  is  the  same  for  all  colours, 
this  method  may  be  applied  either  with  monochromatic  or 
white  light,  the  latter  being  preferable,  not  only  because  the 
illumination  is  greater,  but  also  because,  when  the  true  position 
of  extinction  has  not  been  obtained,  the  two  directions  of  rota- 
tion of  a  nicol  give  different  interference  colours. 

Wright  has  devised  a  bi-nicol  ocular  in  which  the  results  of 
the  rotation  of  two  upper  nicols  in  opposite  directions  may  be 
observed  simultaneously.*  A  similar  effect  is  obtained  by  the 
insertion  of  plates  of  right-  and  left-handed  quartz,  which  rotate 
the  nicol  through  equal  angles  in  opposite  directions.  This  is  the 
principle  of  the  Bertrand  eye-piece,  but  in  its  usual  form  the 
plate  is  so  thick,  2'5  mm.,  that  it  rotates  the  light  through  a 
large  angle,  about  60°  for  sodium  light  and  greater  or  less  amounts 
for  light  with  shorter  or  longer  wave  length.  If  it  be  reduced 
to  a  thickness  of  forty  microns  corresponding  to  a  rotation  of 
1°  for  sodium  light,  much  greater  accuracy  is  obtained,  both 
with  monochromatic    and  white  light,  f 

Wright's  bi-quartz  ivedge  plate,  a  combination  of  wedges  and 
plates  of  quartz,  enables  a  rotation  of  any  convenient  amount 
in  opposite  directions  to  be  obtained.! 

In  all  these  determinations  greater  accuracy  can  be  secured 
by  increasing  the  illumination,  but  care  must  be  taken  that 
the  lower  nicol  is  not  injured  by  over-heating  (see  p.  600). 

It  is  unnecessary  to  dwell  here  on  the  other  methods  which 

*  Loc.  cit.,  pp.  374-376,  379. 

f  S.  Nakamura,Centr.  f.  Min.,  1905,  pp.  267-279. 

%  Am.  Journ.  Set.,  Series  IV.,  vol.  xxvi.,  1908,  pp.  377-380. 


604     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

have  been  introduced  at  different  times  for  the  same  purpose, 
as  few  if  any  of  them  are  so  exact  as  those  which  have  been 
described. 

When  the  stage  is  in  the  exact  position  of  extinction — in  other 
words,  when  the  directions  of  vibration  in  the  crystal  are  parallel 
to  those  of  the  nicols  and  therefore  to  the  cross  wires — the  posi- 
tion of  the  latter  is  indicated  in  the  sketch  by  thick  lines  traversing 
the  whole  field,  and  the  index  reading  is  inserted  on  the  right 
extremity  of  the  right  and  left  cross  wire,  while  the  other 
terminations  of  the  cross  wires  are  distinguished  by  the  corre- 
sponding angular  numbers  differing  by  90°  (see  fig.  1). 

Pleochroism,  etc. — The  light  vibrating  parallel  to  each  direction 
of  vibration  is  differently  affected  by  the  structure  of  the  crystal. 
The  velocity  of  transmission  of  the  vibrations  parallel  to  one  is 
greater  than  that  of  those  parallel  to  the  other  and  the  index  of 
refraction  is  consequently  less  in  the  case  of  the  former.  At 
the  same  time  the  absorption  of  light  may  differ  considerably 
both  in  the  colour  selected  and  in  amount.  For  an  examination 
of  these  differences  the  crystal  is  observed  with  only  one  nicol 
in  place,  and  the  stage  is  rotated  in  turn  into  each  of  the  positions 
in  which  a  direction  of  vibration  is  parallel  to  the  right  and 
left  cross  wire.  This,  as  we  have  seen  (p.  598) ,  should  be  the 
direction  of  vibration  of  the  nicol  that  is  retained.  The  surface 
of  the  mineral,  whether  it  is  rough  or  smooth,  and  its  luminosity 
and  colour  are  observed  in  each  case  and  noted  in  the  sketch 
at  the  right  end  of  the  thick  line  representing  the  corresponding 
direction  of  vibration.* 

Sometimes  the  surface  of  the  crystal  is  distinctly  rougher  in 
one  position  than  in  the  other.  This  indicates  that  there  is 
considerably  more  difference  between  the  refractive  index  of 
the  light  vibrating  parallel  to  the  right  and  left  direction  and 
that  of  the  medium  in  which  the  section  is  mounted  (Canada 
balsam  or  whatever  it  may  be)  in  the  former  case  than  in  the 
latter.  This  phenomenon  is  well  seen,  when  Canada  balsam  is 
the  medium,  in  calcite  and  the  carbonates  isomorphic  to  it, 
as  well  as  in  the  colourless  micas.  It  causes  a  characteristic 
twinkling  effect  when  the  lower  nicol  is  rapidly  rotated. 

Character  of  Directions  of  Vibration. — We  now  proceed  to 
determine  the  character  (or  sign)  of  the  extinctions  or  directions 

*  See  fig.  1. 


THE  MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      605 

of  vibration  in  the  crystal  section — that  is  to  say,  to  ascertain 
which  of  these  is  the  direction  of  vibration  of  light  with  the 
greater  velocity,  and  which  that  of  light  with  the  less  velocity. 
The  character  of  the  former  direction  of  vibration  or  extinction 
is  said  to  be  fast  (  —  )  and  that  of  the  latter  slow  (  -j-  ). 

Relative  Retardation. — We  can  also  determine  at  the  same 
time  the  amount  of  the  relative  retardation — in  other  words,  the 
distance  by  which  the  slow- moving  vibrations  have  lagged 
behind  the  faster.  Both  are  delayed  in  traversing  the  section, 
but  the  former  more  than  the  latter.  Relative  retardation  is 
usually  measured  in  micro-millimetres  or  millionths  of  a  milli- 
metre. The  character  of  any  definite  direction  in  a  crystal 
section,  e.^.tone  of  its  longer  sides,  is  also  said  to  be  fast,  or  slow, 
according  as  it  coincides  or  makes  an  angle  of  less  than  45° 
with  the  fast,  or  the  slow,  directions  of  vibration,  and  to  be 
neutral  when  it  bisects  the  angle  between  them. 

For  the  purpose  of  making  these  determinations  the  section  is 
brought  into  a  position  of  extinction  and  then  the  stage  rotated 
through  45°,  so  that  the  directions  of  vibration  in  the  section  are 
diagonal  to  those  in  the  nicols.  This  is  known  as  the  diagonal 
■position.  One  of  the  directions  of  vibration  in  the  section  will 
then  be  parallel  to  the  slot.  To  ascertain  which  it  is,  the  stage  is 
rotated  through  45°  till  the  direction  which  was  parallel  to  the 
slot  is  in  the  right  and  left  position,  when  the  index  reading  will 
be  that  of  the  direction  required.  The  same  reading  may  be 
obtained  by  adding  or  subtracting,  as  the  case  may  be,  45°  to  or 
from  the  index  reading  in  the  diagonal  position.  For  instance, 
if  the  slot  is  in  the  position  shown  in  fig.  3,  45°  will  be 
added. 

In  the  diagonal  position  the  vibrations  which  pass  the  lower 
nicol  are  resolved  along  the  two  directions  of  vibration  in  the 
section.  If  there  were  no  relative  retardation  between  the 
vibrations  in  these  directions,  thev  would  on  emergence  re- 
combine  to  form,  once  more,  vibrations  parallel  to  the  direction  of 
the  vibration  of  the  light  when  it  left  the  lower  nicol  and  would 
therefore  be  extinguished  by  the  upper  nicol.  As  a  result,  how- 
ever, of  the  relative  retardation  this  is  no  longer  the  case,  and 
the  various  colours  of  the  spectrum  are  transmitted  in  different 
degrees,  so  that  the  compoimd  tints  known  as  interference  colours 
are  obtained.      These  are  dependent  on  the  amount  of  the  relative 


606      J.  W.  EVANS    ON   THE    DETERMINATION    OF    MINERALS    UNDER 

retardation,   which  is  usually  approximately  the  same  for  all 
the  colours  of  the  spectrum. 

Within  certain  limits  every  amount  of  relative  retardation  is 
distinguished  by  its  own  characteristic  interference  tint  between 
crossed  nicols,  and  these  tints  are  practically  the  same  for  the 
majority  of  minerals,  though  the  thickness  required  to  give  rise 
to  a  particular  colour  varies  greatly  for  different  minerals  and 
according  to  the  direction  in  which  the  same  mineral  may  be 
cut.  It  is  only  in  those  minerals  in  which  the  relative  retardation 
varies  for  different  colours  that  unusual  or  anomalous  colours  are 
seen.  These  minerals  are  so  few  in  number  that  the  occurrence 
of  their  characteristic  anomalous  colours  furnishes  a  ready  means 
of  distinguishing  them.  The  indigo- blue  seen  in  many  thin 
sections  of  chlorite  is  a  familiar  example. 

The  normal  interference  colours  commence  with  complete 
darkness  at  zero  relative  retardation  and  pass  through  grey, 
white,  yellow,  orange,  and  red,  at  the  end  of  which  the  relative 
retardation  reaches  550  micro- millimetres.  These  constitute  the 
■colours  of  the  first  order.  Then  follow  purple,  violet,  blue, 
green,  yellow  and  red  up  to  a  relative  retardation  of  1,100.  These 
are  the  colours  of  the  second  order.  Every  addition  of  550  micro- 
millimetres  corresponds  to  another  order  with  a  similar  suc- 
cession of  colours,  which  gradually  become  more  complex  till 
they  are  only  represented  by  delicate  shades  of  green  and  pink, 
and  with  a  relative  retardation  of  about  4,000  micro-millimetres 
they  slowly  pass  into  white  light,  the  '  white  of  the  higher 
orders."  The  colours  are  said  to  be  lower  or  higher  according 
as  they  result  from  a  less  or  greater  amount  of  relative  retar- 
dation. 

If  one  nicol  be  rotated  through  a  quarter  turn  so  that  the 
directions  of  vibration  of  the  two  nicols  are  parallel,  the  com- 
plementary colours  are  seen,  which  commence  with  white  and 
pass  through  brown,  red  and  blue  to  the  yellowish  green  that 
marks  the  end  of  the  first  order  at  550.  The  second  order  passes 
through  yellow,  red  and  blue  to  green  again,  and  in  the  higher 
orders  the  colours  gradually  fade  away  through  pinks  and  greens 
into  white  light  exactly  as  with  crossed  nicols. 

The  amount  of  the  relative  retardation  in  a  crystal  section 
may  often  be  roughly  estimated  directly  from  the  interference 
colours  between  crossed  and  parallel  nicols  by  comparison  with 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      6()7 

a  table  or  lithographic  plate  of  the  colours  with  the  correspond- 
ing relative  retardations,  but  in  determining  colours  so  much 
depends  on  the  idiosyncrasy  of  the  observer  and  the  character 
of  the  light  that  such  estimates  can  only  be  relied  on  within  very 
wide  limits.  In  the  smoky  atmosphere  of  a  London  winter,  for 
instance,  the  blue  of  the  second  order  under  crossed  nicols  appears, 
as  Mr.  T.  Crook  pointed  out  to  me,  to  pass  directly  into  greenish 
yellow  without  anything  that  could  be  definitely  characterised 
as  green  intervening. 

The  birefringence  may  be  denned  as  the  relative  retardation  in 
a  unit  of  distance.  The  relative  retardation  is,  accordingly,  equal 
to  the  product  of  the  birefringence  of  the  section  and  its  thick- 
ness, the  distance  traversed.  It  can  be  shown  that,  if  the  same 
units  are  employed  for  both  relative  retardation  and  distance 
traversed,  the  birefringence  is  equal  to  the  difference  between  the 
refractive  indices  of  the  two  directions  of  vibration. 

If  then  k  be  the  relative  retardation,  I  the  thickness  of  the 
section,  d  the  birefringence  and  /x  and  v  the  refractive  indices 
in  the  fast  and  slow  directions,  we  have  k  =  I  d  =  I  (v  —  li). 

In  the  case  of  a  section  of  quartz  21  microns  thick,  cut  parallel 
to  the  optic  axis,  the  indices  of  refraction  are  1*514  and  1'553 
and  the  birefringence  0*009,  which  is  the  relative  retardation  in 
microns  after  traversing  one  micron.  Accordingly  h  =  21  x  0*009 
=  0*189  of  a  micron. 

If,  however,  the  relative  retardation  be  expressed,  as  usual,  in 
micro-millimetres,  it  will,  foi-  the  same  thickness,  be  numerically 
a  thousandfold  greater.  This  value  of  the  relative  retardation 
may  be  denoted  by  K,  and  tne  corresponding  value  of  the  bire- 
fringence, that  is  to  say  the  relative  retardations  in  micro- 
millimetres  after  traversing  one  micron,  by  D,  which  will  be,  in 
the  same  manner,  numerically  a  thousand  times  d,  the  value  in 
homogeneous  units.  D  may  be  referred  to  as  the  birefringence 
in  millesims,  where  a  millesim  is  a  unit  equal  to  0*001.  The 
equation  then  becomes  K  =  I D.  In  the  special  case  which 
has  been  taken,  the  birefringence  is  9  millesims,  so  that  K  = 
21  x  9  =  189  micro-millimetres.  This  procedure  has  the  advan- 
tage of  avoiding  small  decimal  amounts. 

The  birefringence  varies  according  to  the  direction  in  which 
the  section  is  cut  in  the  crvstal.  The  value  given  in  text-books 
is  the  maximum  birefringence,  that  found  in  sections  cut  parallel 


608      J.  W.  EVANS    ON   THE    DETERMINATION    OF    MINERALS  UNDER 

to  the  optic  axis  in  uniaxial  crystals,  and  to  the  optic  axial  plane 
in  biaxial  crystals.  The  actual  birefringence  in  a  section  may 
be  anything  between  this  and  zero. 

The  maximum  birefringence  in  millesims  may  be  obtained 
from  the  value  in  homogeneous  units  found  in  text-books  by 
moving  the  decimal  point  three  places  to  the  right. 

The  Quartz  Wedge. — If  the  relative  retardation  is  to  be  de- 
termined at  the  same  time  as  the  character  of  the  directions 
of  vibration,  a  quartz  wedge  or  mica  steps  must  be  employed. 
The  quartz  wedge  is  cut  in  this  country  with  its  length  parallel 
to  the  optic  axis,  which  is  the  direction  of  vibration  of  the  light 
propagated  with  the  least  velocity.  The  length  is  therefore 
slow  (  -f-  )  while  the  width  is  fast  (  —  ).  As  wedges  are  some- 
times cut  in  different  directions,  the  character  of  the  length 
should  be  engraved  on  the  glass  as  shown  in  fig.  3. 

The  wedge  should  be  graduated  so  as  to  indicate  the  relative 
retardation  at  different  points  (see  fig.  3).  It  should  be  inserted 
in  focus  (see  p.  599),  otherwise  the  colours  will  be  blurred  from 
overlapping  and  the  graduation  be  invisible. 

If  the  wedge  be  inserted  in  the  slot  between  crossed  nicols, 
when  there  is  no  birefringent  mineral  in  the  field  or  none  which 
is  not  in  the  position  of  extinction,  the  normal  succession  of  inter- 
ference colours  is  seen  commencing  at  the  thin  end  of  the  wedge, 
where,  however,  the  black  and  darker  grey  are  usually  missing 
on  account  of  the  difficulty  of  preserving  the  thin  end  from 
abrasion. 

If,  however,  there  is  a  birefringent  mineral  present  in  the 
diagonal  position,  so  that  the  directions  of  vibration  of  the  light 
traversing  it  are  parallel  and  at  right  angles  to  the  slot,  and 
therefore  parallel  to  those  of  light  traversing  the  quartz  wedge, 
the  relative  retardation  of  light  traversing  both  the  mineral  and 
the  wedge  will  be  the  combined  effect  of  the  relative  retardation 
in  each. 

If  the  directions  of  the  slow  (  +  )  and  fast  (  —  )  vibrations 
respectively  in  the  mineral  are  the  same  as  in  the  quartz 
wedge,  the  colour  seen  at  any  point  where  the  two  are  superposed 
will  correspond  to  a  relative  retardation  equal  to  the  sum  of  the 
relative  retardations  of  both.  This  may  be  referred  to  as 
the  additive  position.  As  the  length  of  the  quartz  wedge  is  slow 
(  +  ),  the  direction  in  the  crystal  which  coincides  with  that  of 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      609 

the  slot  must  evidently  in  this  case  also  be  slow  (  -f-  ).  If  on 
the  other  hand  the  slow  direction  of  the  wedge  correspond  with 
the  fast  direction  in  the  crystal  section  and  vice  versa,  the  resulting 
relative  retardation  will  be  equal  to  the  difference  of  relative  re- 
tardations in  the  two,  and  they  may  be  said  to  be  in  the  subt) 'active 
position  (fig.  3).  In  this  case  the  direction  in  the  crystal  section 
parallel  to  the  length  of  the  wedge  and  therefore  to  the  slot  will 
be  fast  (  —  ).  If  the  relative  retardation  of  the  crystal  section  be 
within  the  limits  of  relative  retardation  shown  by  the  wedge, 
there  will,  as  the  wedge  is  advanced  through  the  slot  in  the 
subtractive  position,  be  ultimately  seen  a  black  band  traversing 
the  crystal  at  right  angles  to  the  length  of  the  wedge.  This 
marks  the  point  where  the  relative  retardation  in  the  wedge 
exactly  neutralises  that  in  the  crystal  section,  being  equal  to  it 
but  opposite  in  character.  The  relative  retardation  shown  in 
the  graduation  of  the  wedge  at  the  point  where  the  black  band 
appears  must  therefore  be  that  of  the  section  also. 

If  the  mineral  gives  rise  to  very  high  relative  retardation  and 
shows  only  pale  pink  and  green  tints  or  the  white  of  the  higher 
orders,  except  on  the  margin  where  bands  of  the  lower-order 
colours  are  visible,  the  character  of  the  section  may  most  easily 
be  determined  by  noticing  how  these  bands  move  when  the 
wedge  is  inserted.  If  they  move  inward  from  the  margin,  the 
mineral  and  the  wedge  are  in  the  subtractive  position ;  if  out- 
wards towards  the  margin,  in  the  additive  position.  In  such 
cases  it  is  frequently  desirable  to  employ  an  especially  thick 
wedge  with  a  comparatively  large  angle.  It  sometimes  happens 
in  the  case  of  minerals  with  high  birefringence  that,  even  when 
the  wedge  is  inserted  in  the  subtractive  position  and  the  relative 
retardation  at  its  thick  end  exceeds  that  of  the  mineral,  no 
definite  black  band  can  be  recognised,  but  when  the  wedge  is 
inserted  up  to  a  certain  point,  irregular  lines  appear,  which 
are  too  thin  for  the  colours  to  be  recognised,  and  when  the 
wedge  is  pushed  still  farther  in,  they  disappear.  The  mean  of 
the  values  of  the  relative  retardations  of  the  quartz  wedge  at 
the  points  where  these  lines  appear  and  disappear  may  be  taken 
as  that  of  the  mineral  under  examination. 

In  all  cases  of  difficulty  in  making  this  determination  it  is 
best  to  use  strictly  parallel  light. 

With  strongly  pleochroic  minerals  the  black  band  does  not 

Jourx.  Q.  M.  C,  Series  II.— No.  77.  34 


610     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

occur,  as  the  excessive  absorption  of  some  or  all  colours  in  one 
direction  prevents  the  recombination  of  the  vibrations  to  form 
light  vibrating  parallel  to  the  right  and  left  cross  wires.  For 
the  same  reason  the  interference  colours  of  such  minerals  are 
abnormal.  As  already  stated,  a  similar  result  is  obtained  also 
where  the  birefringence — and  therefore  the  relative  retardation — 
varies  considerably  for  different  colours  (see  p.  606).  In  either 
case  it  is,  however,  generally  possible  to  estimate  with  a  fair 
amount  of  accuracy  the  central  position  from  which  the 
relative  retardation  with  its  corresponding  colours  increases  in 
both  directions. 

Pleochroic  sections  may  be  referred  to  as  slow-dark  and  fast- 
dark  according  as  the  character  of  the  direction  of  maximum 
absorption  is  slow  or  fast.  The  latter  case  is  comparatively  rare, 
and  when  it  occurs,  as  in  aegyrine,  riebeckite,  arfvedsonite, 
apatite,  and  andalusite,  is  of  considerable  diagnostic  value. 

Similarly,  where  the  colour  varies  considerably,  crystal  sec- 
tions may  be  termed  fast-red  and  slow-green,  or  as  the  case  may 
be.  Where  the  contrast  is  between  red  on  the  one  hand  and 
blue  or  green  on  the  other,  the  fast  vibrations  are  usually  asso- 
ciated with  the  former. 

In  the  double  quartz  wedge  (fig.  4)  which  I  described  in  the 
Mineralogical  Magazine  (vol.  xiv.  (1905),  pp.  91-2)  there  are  two 
wedges,  one  with  the  length  slow  (  +  )  and  the  width  fast  (  —  ), 
the  other  with  these  characters  reversed.  They  have  the  same 
angle  and  the  same  birefringence,  so  that  when  cemented  by 
Canada  balsam  side  by  side  on  a  glass  slip  and  inserted  in 
the  slot  between  crossed  nicols  the  colours  stretch  across  the 
two  component  wedges  exactly  as  if  they  were  one  ;  but  if  a 
birefringent  crystal  section  be  in  the  field  with  its  directions  of 
vibration  parallel  and  at  right  angles  to  the  slot,  one  side  will 
show  additive  effects  and  the  other  subtractive,  so  that  the 
existence  of  a  small  relative  retardation  is  easily  recognised,  and 
the  amount  of  the  relative  retardation  may  be  read  off  which- 
ever direction  of  vibration  in  the  crystal  section  is  parallel  to 
the  slot.  It  may  be  noted  that  the  colour  in  one  component 
wedge  opposite  the  black  band  in  the  other  corresponds  to  a 
relative  retardation  exactly  double  that  of  the  crystal  section 
under  examination. 

All  forms  of  quartz  wedge  should  be  carefully  calibrated  by 


THE    MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      611 

means  of  the  dark  and  light  bands  which  replace  the  colours 
in  mono-chromatic  light.  The  error  may  be  thus  determined 
within  ten  micro-millimetres. 

Gypsum  Plate. — If  the  relative  retardation  be  very  small  it  is 
difficult  to  detect  or  measure  it  by  a  quartz  wedge  on  account 
of  the  imperfection  of  the  thin  edge  of  the  latter.  It  is  best 
investigated  by  means  of  a  gypsum  plate,  parallel  to  the  clino- 
pinakoidal  cleavage,  of  such  a  thickness  as  to  show  the  violet 
corresponding  to  a  relative  retardation  of  575  micro-millimetres. 
A  very  small  decrease  in  the  relative  retardation  is  sufficient  to 
modify  the  colour  considerably  and  cause  it  to  pass  into  purple 
or  red,  while  a  slight  increase  changes  it  to  indigo  or  blue.* 

The  gypsum  plate  is  usually  cut  with  its  length  parallel  to 
the  fast  direction.!  It  may  be  inserted  in  either  slot  or  in  any 
other  place  in  the  course  of  the  light  between  crossed  nicols,  but 
always  in  a  diagonal  direction.  If  a  crystal  section  with  low 
birefringence  is  now  placed  on  the  stage  with  its  directions  of 
vibration  parallel  and  at  right  angles  respectively  to  this 
direction,  the  colour  of  the  plate  will  be  seen  to  be  modified 
so  as  to  indicate  an  increase  or  decrease  in  the  relative  retarda- 
tion. In  the  former  case  the  vibrations  in  the  crystal  parallel 
to  the  slot  will  be  fast,  in  the  latter  slow.  J 

To  determine  the  relative  retardation  of  the  crystal  section, 
that  of  the  combination  is  determined  by  means  of  the  quartz 
wedge  and  the  position  of  the  black  band  on  it.  The  stage  is 
then  rotated  through  an  angle  of  90°  and  the  determination 
repeated.     Half  the  sum  will  be  the  relative  retardation  of  the 

*  Gypsum  plates  are,  however,  usually  made  to  show  the  red  of  the 
first  or  second  order,  which  is  not  so  sensitive  to  variations  in  thickness 
and  therefore  easier  to  produce  of  a  practically  uniform  tint. 

f  A  circular  plate  mounted  in  wood  is  to  be  avoided,  for  if  it  becomes 
loose,  as  frequently  happens,  it  loses  its  correct  orientation.  The 
plate  should  be  marked  so  as  to  show  the  numerical  amount  of  the 
relative  retardation  and  the  character  of  the  length,  as  in  fig.  5. 

J  In  the  case  of  small  minerals  with  low  relative  retardation,  which 
are  rendered  inconspicuous  by  the  bright  light  to  which  the  gypsum 
plate  gives  rise,  it  is  better,  if  the  construction  of  the  microscope  permits, 
to  insert  the  plate  in  a  direction  making  only  a  small  angle  with  the 
cross  wire.  This  diminishes  the  illumination  due  to  the  plate  without 
affecting  appreciably  the  illumination  and  colour  of  the  mineral  under 
examination  (F.  E.  Wright,  Am.  Journ.  Sc,  series  IV.,  vol.  xxxv., 
1913,  p.  66). 


612      J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

gypsum  plate  (which  should  agree  with  its  previously  ascertained 
value)  and  half  the  difference  that  of  the  crystal  section.  If 
the  gypsum  plate  and  quartz  wedge  are  to  be  used  together, 
the  former  should  be  inserted  in  the  lower  slot,  leaving  the  upper 
for  the  latter  ;  the  upper  nicol  would  then  be  necessarily  placed 
above  the  eye-piece. 

F.  E.  Wright  has  devised  a  useful  combination  of  quartz  wedge 
and  gypsum  plate,*  and  I  have  employed  the  same  idea  in  the 
following  manner  (fig.  5).  A  quartz  wedge  is  superposed  on 
a  gypsum  plate  showing  the  sensitive  tint,  both  being  con- 
structed with  the  usual  orientation  (see  above),  so  as  to  leave 
beyond  the  thin  end  of  the  wedge  a  square  of  gypsum  which 
may  be  used  as  an  ordinary  gypsum  plate.  The  quartz  will 
show  a  black  band  where  it  exactly  neutralises  the  gypsum, 
and  the  same  succession  of  colours  in  opposite  directions  from 
this  point,  which  is  indicated  by  a  line  marked  zero  ;  but 
those  on  one  side  stop  short  a  little  before  the  colour  of  the 
plate  is  reached.  Every  hundred  micro-millimetres  of  relative 
retardation  on  either  side  is  shown  by  graduations.  If  the 
direction  of  the  crystal  section  parallel  to  the  slot  be  fast  (  —  ) 
the  black  band  will  move  towards  the  thick  end  of  the  wed»;e,  if 
slow  (  +  ),  towards  the  thin  end. 

Mica  Steps  (fig.  6)  consist  of  a  succession  of  narrow  cleavage 
plates  of  muscovite  with  their  length  cut  parallel  to  the  trace 
of  the  optic  axial  plane  and  therefore  slow.  Each  strip  should 
have  a  relative  retardation  of  a  hundred  micro-millimetres. 
They  are  of  different  lengths,  and  when  superposed  form  a  suc- 
cession of  steps  each  large  enough  to  cover  the  whole  cone  of 
light  in  the  lower  slot,  where  they  are  usually  employed,  though 
they  are  equally  useful  in  the  focus  of  the  eye-piece,  if  the  upper 
nicol  be  placed  above  them.  In  either  case  they  show  a  dis- 
continuous series  of  colours  corresponding  to  differences  of  one 
hundred  micro-millimetres.  If  they  are  inserted  over  a  crystal 
section  it  is  easy  to  see  whether  the  two  show  additive  or  sub- 
tractive  relations.  In  the  former  case  the  stage  should  be  rotated 
till  the  fast  direction  of  the  crystal  section  is  parallel  to  the  slot. 
It  may  then  happen  that  the  crystal  section  is  exactly  neutralised 
by  one  of  the  steps  and  must  therefore  have  the  same  relative 

*  Journal  of  Geology,  vol.  x.,  1902,  pp.  33-35.  See  also  Min. 
Petr.  Mitt.  (Tschermak),  vol.  xx.,  1901,  pp.  275-6. 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      613 

retardation.  Usually,  however,  while  one  of  the  steps  faite  to 
neutralise  the  section,  the  next  higher  will  more  than  do  so,  and 
neither  will  be  completely  dark.  If  they  are  equally  bright, 
the  relative  retardation  of  the  section  must  be  midway  between 
those  of  the  two  steps.  If  one  be  darker  than  the  other  the 
relative  retardation  will  be  proportionately  nearer  to  that  of 
the  darker  step.  In  this  way  it  will  be  possible  to  estimate  the 
relative  retardation  to  within  twenty  or  thirty  micro-millimetres. 

If  a  further  approximation  be  desired  it  may  be  obtained  by 
employing  additional  smaller  mica  steps  divided  into  four  portions 
with  twenty,  forty,  sixty  and  eighty  micro-millimetres  relative 
retardation  respectively.  If  the  larger  mica  steps  are  inserted  in 
the  lower  slot,  the  smaller  can  be  placed  in  the  upper.  In  this 
way  it  is  possible  to  determine  relative  retardation  to  within 
ten  micro-millimetres  and  make  estimations  to  within  half  that 
amount. 

Mica  steps  are  one  of  the  many  useful  pieces  of  apparatus 
devised  by  Fedorov,  but  the  description  given  above  differs 
from  his  directions  in  some  details,  having  reference  chiefly  to 
the  amount  of  the  relative  retardation  represented  by  each  step. 

Mica  steps  may  be  calibrated  by  reference  to  a  quartz  wedge 
the  errors  of  which  have  already  been  determined. 

In  order  to  obtain  the  birefringence  of  the  section  from  the 
relative  retardation  it  is  necessary  to  determine  the  thickness. 
As  this  will  usually  involve  the  movement  of  the  rock-slice  it 
is  better  postponed  till  after  the  "  directions-image  "  has  been 
examined.  For  the  same  reason  the  determination  of  the 
refractive  index  should  also  be  deferred  to  a  later  stage. 

The  Directions-Image. 

It  is  frequently  desirable  to  examine  simultaneously  the 
•optical  properties  of  a  number  of  different  directions  in  a  mineral, 
so  that  a  comprehensive  idea  of  its  optical  characters  may  be 
obtained.  For  this  purpose  the  microscope  is,  in  the  manner 
which  will  be  described,  converted  into  an  optical  instrument 
in  which  every  point  in  the  image  corresponds  not  to  a  point 
in  the  object  under  examination,  but  to  a  direction  along  which 
light  traverses  that  object  in  parallel  paths.  Such  an  instrument- 
may  be  conveniently  described  as  a  hodoscope  or  path  viewer,  a 


614     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

term  which  is  to  be  preferred  to  the  word  "  konoscope  "  employed 
by  some  authors. 

If  a  microscope,  from  which  the  eye-piece  had  been  removed, 
were  directed  vertically  upwards  towards  a  cloudless  sky  at 
night,  the  images  of  all  the  brighter  stars  within  a  certain  distance 
of  the  zenith,  dependent  on  the  angular  aperture  of  the  objective, 
would  be  seen  on  the  principal  focal  surface  of  the  objective — 
that  is  to  say,  its  focal  surface  for  light  from  an  infinite  distance. 
Each  of  these  images  would  be  formed  of  light  which  had  been 
travelling  by  parallel  paths,  or  in  other  words  in  the  same  direc- 
tion, which  would  of  course  be  different  for  different  stars.  By 
day  the  whole  field  would  be  illuminated  and  every  point  in  it 
would  represent  light  which  had  reached  the  objective  from  a 
particular  direction.  If  a  mineral  section  were  now  interposed 
close  to  the  objective,  every  illuminated  point  on  the  focal 
surface  would  represent  a  direction  in  the  crystal  section,  which 
would  be  determined  by  the  construction  of  the  objective,  the 
position  of  the  point  relatively  to  it  and  the  refraction  at  the 
surface  of  the  section.  The  image  thus  obtained  representing 
different  directions  in  a  mineral  may  be  described  as  the  directions- 
image,  as  opposed  to  the  object-image  in  which  the  microscope 
is  focused  on  the  object  itself. 

As  it  is  inconvenient  to  direct  the  microscope  to  the  sky,  the 
different  directions  in  the  mineral  section  are  illuminated  by 
placing  below  the  stage  and  above  the  mirror  of  the  microscope 
a  condenser  consisting  of  a  convergent  lens  or  system  of  lenses. 
For  this  reason  the  directions-image  is  frequently  referred  to 
as  the  "image  in  convergent  light,"  an  altogether  misleading- 
expression,  since  convergent  light  is  habitually  employed 
with  close  objectives,  when  the  microscope  is  focused  on  the 
object  itself,  or  in  other  words  when  the  object-image  is  under 
examination.  In  observing  the  directions-image  it  is  usually 
desirable  to  employ  wide-angled  objectives,  so  as  to  include 
as  many  directions  as  possible,  and  the  angular  aperture  of 
the  condenser  must  be  at  least  as  great. 

The  directions-image  of  small  crystals,  grains  and  fragments 
may  be  examined  in  like  manner,  though  the  results  are  modified 
by  the  varying  effects  of  refraction  at  different  points,  unless 
the  medium  in  which  the  object  is  immersed  has  approximately 
the  same  index  of  refraction  as  the   object  itself.      The  inter- 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      615 

ference  colours  are  also  affected  by  the  variations  in  the  thick- 
ness traversed,  even  by  light  moving  in  parallel  directions. 

The  Bertrand  Lens. — As  the  directions-image  formed  by  the 
objective  is  small  and  somewhat  inaccessible,  it  is  usual  to 
employ  a  Bertrand  lens,  a  convex  lens,  which  is  placed,  when 
required,  in  the  tube,  and  forms  a  secondary  directions-image 
in  the  focus  of  the  eye-piece.  The  Bertrand  lens  is,  as  a  rule, 
inserted  a  short  distance  above  the  objective,  but  is  sometimes 
placed  higher  up,  and  then  occupies  only  the  centre  of  the  tube, 
so  that  a  large  portion  of  the  object-image  may,  if  desired, 
be  left  visible.  If  this  be  done,  the  observer  can,  without  losing 
sight  of  the  directions-image  satisfy  himself  from  time  to  time 
as  to  the  point  on  which  the  microscope  is  .  directed  and,  if 
desired,  change  from  one  portion  of  the  crystal  section  to  another. 

The  Bertrand  lens  should  be  capable  of  being  focused  by  a 
sliding  movement  along  the  axis  of  the  microscope,  and  it  is  im- 
portant that  this  movement  should  have  sufficient  range  for  the 
purpose,  which  is  not  always  the  case. 

The  Becke  Lens. — Instead  of  inserting;  the  Bertrand  lens  in 
the  tube,  it  is  possible  to  obtain  the  same  result  more  conveniently 
by  placing  the  Becke  lens  above  the  eye-piece.  This  is  a  convex 
lens  or  system  of  lenses,  similar  to  a  Ramsden  eye-piece,  which 
magnifies  the  directions-image  formed  in  the  Ramsden  circle  of 
the  eye-piece.     It  should  have  a  focusing  movement. 

Isolation  of  the  Directions-Image  of  a  Mineral. — If  the  mineral 
under  examination  is  not  alone  in  the  field,  it  is  desirable  to 
isolate  it  so  that  the  effects  of  different  minerals  may  not  be 
blended  and  thus  interfere  with  one  another. 

This  object  may  sometimes  be  attained  by  using  a  closer 
objective  and  thus  diminishing  the  extent  of  the  rock-slice  or 
glass  slip  included  in  the  field. 

A  more  generally  available  method,  however,  is  to  cut  off 
all  light  except  that  reaching  the  mineral  under  examination. 
For  this  purpose  a  diaphragm  may  be  placed  a  little  distance 
below  the  condenser,  which  is  adjusted  so  that  the  image  of 
the  aperture  in  the  diaphragm  is  focused  simultaneously  with 
the  object. 

In  some  microscopes  the  iris  diaphragm,  attached  to  the 
condenser  for  carrying  out  the  Becke  method  of  determining 
the  relative  refractive  indices  of  minerals  in  thin  sections  (p.  626). 


616      J.    W.    EVANS    ON    THE    DETERMINATION  OF  MINERALS    UNDER 

may  be  employed.*  In  that  case  all  that  is  necessary  is  to  focus 
the  microscope  on  the  object,  and  after  nearly  closing  the  dia- 
phragm lower  the  condenser  till  the  aperture  in  the  diaphragm 
appears  in  focus.  The  glass  slip  is  then  adjusted,  if  necessary, 
so  that  the  mineral  to  be  observed  is  in  the  centre  of  the  field 
and  the  diaphragm  opened  or  closed  till  the  maximum  area  of 
that  mineral,  but  no  portion  of  any  other,  is  illuminated,  f  It  is 
scarcely  necessary  to  add  that  the  greatest  care  must  be  taken 
to  see  that  the  nose-piece  is  exactly  centred  so  that  the  object 
remains  in  the  illuminated  area  during  the  rotation  of  the  stage. 
The  Bertrand  or  Becke  lens  is  now  placed  in  position  and  the 
directions-image  can  be  studied. 

The  same  result  can  be  obtained  by  placing  a  diaphragm  at 
any  point  above  the  object  where  a  real  object-image  is  formed, 
provided  of  course  that  it  is  not  affected  by  the  conversion  of 
the  microscope  into  a  hodoscope.  One  of  the  following  methods, 
preferably  the  second,  may  be  employed  : 

1.  If  the  eye-piece  be  removed,  an  object-image  can  be  formed 
exactly  at  the  upper  end  of  the  microscope  tube  by  operating  the 
coarse  or  fine  adjustment.  The  mineral  selected  for  examination 
is  then  brought  into  the  centre  of  the  field  and  a  cap  with  a 
•central  perforation,  not  larger  than  the  image  of  the  mineral,  is 
placed  on  the  end  of  the  tube.  If  the  eye  be  now  placed  close 
to  the  aperture,  the  directions- image  will  be  seen  low  down  in 
the  tube  in  the  position  already  described,  illuminated  only  by 
light  which  has  traversed  the  mineral. 

2.  The  eye-piece  may  be  retained  and  the  mineral  to  be  studied 
isolated  by  means  of  a  diaphragm  in  the  focus  of  the  eye-piece. 
The  Becke  lens  is  then  placed  in  position  and  the  directions- 
image  of  the  mineral,  unmixed  with  other  light,  is  seen. 

3.  If  the  Bertrand  lens  be  employed,  an  object-image  is 
formed  above  it  and  below  the  eye-piece,  and  can  be  seen  if  the 
eye-piece  be  removed.  A  diaphragm  may  be  inserted  here, 
but  the  low  magnification  of  the  image  is  a  drawback.  A 
diaphragm   is  frequently  placed   just   below  the  Bertrand  lens. 

*  In  other  instruments  the  iris  diaphragm  is  so  close  to  the  condenser 
that  the  latter  cannot  be  lowered  sufficiently  to  bring  it  into  focus. 
Another  diaphragm  must  then  be  provided. 

f  Light  traversing  glass  or  other  isotropic  substances  will  not, 
however,  affect  the  result,  if  the  nicols  be  crossed. 


THE  MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.       617 

Iii  that  case  to  make  the  object-image  coincide  with  the  dia- 
phragm, a  lens,  or  a  combination  of  a  lens  with  the  eye-piece,  is 
focused  on  the  position  of  the  diaphragm  and  the  tube  raised  till 
the  object  is  seen  in  focus.  The  angle  of  the  cone  illuminated  by 
the  condenser  is,  however,  diminished  by  the  elevation  of  the 
objective. 

I  now  proceed  to  describe  some  of  the  phenomena  seen  in  the 
directions-image,  especially  those  which  may  be  easily  observed 
in  minerals  in  thin  sections  and  afford  important  information  with 
regard  to  their  optical  characters,  as  well  as  the  directions  in 
which  they  have  been  cut. 

Interference  Colours  in  the  Directions-Image.  —  When  the 
directions-image  is  examined  between  crossed  nicols  it  shows 
in  the  centre  of  the  field  the  same  interference  colour  as  that 
seen  in  the  object-image.  From  the  centre  outwards  this  passes 
into  other  colours  corresponding  to  different  amounts  of  relative 
retardation  which  may  be  greater  or  less  than  that  in  the  centre. 
The  colours  move  with  the  stage  as  it  rotates  without  sufferino- 
•any  change  of  configuration. 

Isogyres. — At  the  same  time  the  field  is  traversed  by  dark 
bands  or  brushes,  which  constitute  the  isogyre*  As  the  rotation 
proceeds,  this,  as  a  rule,  changes  both  its  position  and  its  shape 
and  from  time  to  time  leaves  the  field  altogether. 

When  the  stage  is  in  the  position  corresponding  to  extinction 
in  the  object-image,  in  other  words  when  the  vibrations  in  the 
plane  of  the  crystal  section  are  parallel  to  the  cross  wires,  the 
isogyre  passes  through  the  centre  of  the  field  and  is  known  as  a 
central  isogyre  (figs.  7,  8,  13,   16-21). 

The  visible  portion  of  the  isogyre  consists  in  the  majority  of 
cases  of  a  single  dark  band,  which  usually  expands  towards  the 
margin  of  the  field  to  form  a  less  definite  brush.  This  moves 
four  times  across  the  field  as  the  stage  rotates,  being  usually 
lost  to  view  in  the  intervals. 

In  other  cases  the  isogyre  consists  of  two  dark  bands  which 
either  meet  in  a  cross  or  form  the  two  branches  of  an  hyperbola. 

The  following  special  types  of  central  isogyres  formed  of  a 
single  band  may  be  distinguished. 

A  symmetrical  isogyre  is  straight   and  parallel  to  one  of  the 

*  F.  Becke,  Min.  Petr.  Mitt.  (Tschermak),  vol.  xxiv.,  1905, pp.  1-34, and 
Min.  Mag.  vol.  adv.-,  1907,  pp.  27G-80,  and  J.  W.  Evans,  ib.  pp.  230-3. 


618     J.  W.  EVANS    ON   THE    DETERMINATION    OF    xMINERALS    UNDER 

cross  wires  and  therefore  to  one  of  the  directions  of  vibration  in 
the  section  (figs.  7,  8  and  17).  A  section  showing  a  symmetrical 
isogyre  is  itself  said  to  be  symmetrical. 

A  symmetrical  section  is  always  cut  at  right  angles  to  a  plane 
of  optical  symmetry,  of  which  the  central  isogyre  is  the  trace. 

Every  section  of  a  uniaxial  mineral  is  cut  at  right  angles  to  a 
plane  of  optical  symmetry,  while  this  is  only  exceptionally  the 
case  wTith  sections  of  biaxial  crystals.  If,  therefore,  every  section 
of  a  mineral  in  a  rock  section  shows  a  symmetrical  isogyre,  we 
may  safely  assume  that  the  mineral  is  uniaxial. 

As  a  general  rule  in  biaxial  crystals  a  central  isogyre  is  curved 
and  oblique  to  the  cross  wires  (figs.  16,  19). 

A  pseudosymmetric  isogyre  is  straight,  but  is  parallel  not 
to  one  of  the  cross  wires,  but  to  the  line  bisecting  the  angle 
between  them  (fig.  18). 

A  pseudosymmetric  section  is  only  met  with  in  crystals 
whose  optic  axial  angle  is  90°  and  the  normal  of  such  a  section 
lies  in  one  of  the  planes  containing  the  optic  normal  and  one 
of  the  optic  axes  of  the  crystal. 

If  an  isogyre  is  formed  of  two  bars,  but  only  one  of  these 
passes  through  the  centre  of  the  field,  the  nature  of  the  isogyre 
and  of  the  section  is  determined  by  the  portion  of  the  isogyre 
which  passes  through  the  centre. 

If  the  two  bars  meet  at  right  angles  in  the  centre  and  form  a 
cross,  they  are  both  straight  and  parallel  to  the  cross  wires  and 
therefore  symmetrical.  The  section  must  accordingly  have  been 
cut  at  right  angles  to  two  planes  of  optical  symmetry  and  to 
the  line  of  optical  symmetry  in  which  they  meet.  In  a  biaxial 
crystal  this  line  is  either  a  bisectrix  or  the  optic  normal.  In 
the  latter  case,  the  cross  is  somewhat  indistinct  and  in  crystals 
with  an  optic  axial  angle  approaching  a  right  angle  it  becomes 
unrecognisable.  If  a  section  of  a  uniaxial  crystal  show  a  central 
cross,  it  is  either  cut  at  right  angles  to  the  optic  axis,  and  therefore 
to  an  infinite  number  of  planes  of  optical  symmetry,  or  it  is 
parallel  to  the  optic  axis.  In  the  latter  case,  again,  the  cross 
is  indistinct. 

The  Movements  of  Isogyres. — The  movements  of  a  symmetrical 
isogyre,  when  the  stage  is  rotated  alternately  in  opposite  directions, 
are  symmetrical  to  the  cross  wire  to  which  it  is  parallel,  while 
those  of  a  pseudosymmetric  isogyre  are  symmetrical  in  the  same 


THE   MICROSCOPE   BY   MEANS  OF  THEIR  OPTICAL  CHARACTERS.     619 

way  to  the  diagonal  to  which  it  is  parallel.     If  the  movements 
are  unsymmetrical,  the  isogyre  must  be  so  likewise. 

If,  when  the  stage  is  rotated,  one  of  the  ends  of  an  isogyre 
at  the  boundary  of  the  field  moves  round  the  circumference 
in  the  same  cyclical  direction  as  that  in  which  the  stage  is 
rotated,  that  end  is  said  to  be  proximal.  If  it  moves  round 
in  the  opposite  direction  or  is  stationary,  it  is  distal.  The 
terms  homodrom  and  antidrom  are  used  by  Becke,  but  they 
are  misleading,  if  a  microscope  with  rotating  nicols  be  employed, 
and  proximal  and  distal  are  accordingly  more  suited  for  general 
use.  The  manner  in  which  they  are  applied  is  illustrated  in 
figs.  7,  9-11  and  16-18. 

An  isogyre  consisting  of  a  single  band  has  usually  one  end 
proximal  and  the  other  distal.  A  proximal  end  is  directed 
towards  the  nearest  optic  axis,  or,  if  it  be  practically  equidistant 
from  the  two  optic  axes,  to  the  nearest  bisectrix. 

An  isogyre  consisting  of  two  bars  intersecting  in  a  cross 
has  in  biaxial  crystals  (fig.  13)  two  proximal  ends  opposite  to 
each  other  and  two  distal  ends.  If  the  centre  of  the  cross  repre- 
sents a  bisectrix,  the  proximal  ends  are  directed  towards  the 
optic  axes  and  the  bar  to  which  they  belong  marks  the  trace  of  the 
optic  axial  plane.  The  distal  ends  lie  in  the  direction  of  the  optic 
normal.  If  the  section  is,  on  the  other  hand,  cut  at  right  angles  to 
the  optic  normal,  the  proximal  ends  point  to  the  acute  bisectrix 
and  the  distal  towards  the  obtuse  bisectrix. 

On  rotation  of  the  stage  the  cross  breaks  up  into  two  hyper- 
bolic branches,  each  with  one  proximal  and  one  distal  end.  These 
move  away  from  the  centre  and  may  pass  entirely  out  of  the  field. 
In  sections  of  uniaxial  crystals  cut  at  right  angles  to  the  optic 
axis  (fig.  21)  the  cross  does  not  break  up  on  the  stage  being  rotated, 
and  the  ends  are  stationary  and  therefore  distal.  The  phenomena 
:n  sections  parallel  to  the  optic  axis  are  similar  to  those  in 
sections  at  right  angles  to  the  optic  normal  in  biaxial  crystals. 
The  proximal  ends  are  directed  towards  the  optic  axis,  while 
the  bar  with  distal  ends  lies  in  the  plane  of  optical  symmetry 
at  right  angles  to  the  optic  axis. 

If  the  distal  end  of  an  isogyre  move  more  rapidly  than  the 
proximal  end,  the  movement  may  be  compared  to  that  of  a 
pendulum.  This  happens  when  the  proximal  end  is  directed 
towards   an   optic  axis.     If  the  section  is  symmetrical,  either 


620     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

it  is  at  right  angles  to  the  optic  axial  plane  of  a  biaxial  crystal, 
•or  it  is  a  section  of  a  uniaxial  crystal,  which  makes  a  very 
large  angle  with  the  basal  plane. 

If  both  ends  move  at  nearly  the  same  rate,  the  isogyre  passes 
straight  across  the  field,  maintaining  approximately  its  rectilinear 
form  and  keeping  parallel  to  one  of  the  cross  wires  (fig.  11).  This 
is  the  case  in  sections  of  uniaxial  crystals  which  make  only  a 
moderate  angle  with  the  basal  plane.  It  is  not  the  only  move- 
ment occurring  in  isogyres  of  uniaxial  minerals,  as  is  commonly 
supposed  to  be  the  case. 

Longitudinal  and  Transverse  Directions. — A  direction  of  vibra- 
tion (or  extinction)  is  said  to  be  longitudinal,  when  it  is  parallel 
to  the  central  isogyre  where  it  passes  through  the  centre,  or 
when  it  makes  an  angle  of .  less  than  45°  with  it.  The  transverse 
direction  of  vibration  is  that  at  right  angles  to  the  longitudinal 
direction.  If  a  central  isogyre  is  diagonal,  that  is  to  say  if  it 
bisects  the  angle  between  the  cross  wires,  the  directions  of 
vibration  are  neither  longitudinal  nor  transverse: 

The  ends  of  a  longitudinal  direction  nearest  to  the  proximal 
<and  distal  ends  of  the  isogyre  may  themselves  be  described  as 
proximal  and  distal  respectively. 

In  a  central  cross  which  breaks  up  into  hyperbolic  branches 
when  the  stage  is  rotated,  the  horizontal  or  vertical  bar  with  two 
proximal  ends  marks  the  longitudinal  direction,  and  in  the 
diagonal  position  becomes  the  axis  of  the  hyperbola,  if  one  be 
visible  (figs.  13  and  14). 

If  there  be  a  central  cross  which  does  not  break  up,  the  section 
is,  as  already  stated,  cut  at  right  angles  to  the  optic  axis  of  a 
uniaxial  crystal,  and  all  directions  are  longitudinal  (fig.  21). 

The  Character  of  Isogyres  and  Sections. — The  character  (sign) 
of  a  central  isogyre  is  that  of  the  longitudinal  direction  (see  p.  605), 
and  the  same  character  is  attributed  to  the  section  itself.  A 
diagonal  isogyre  and  its  section  are  said  to  be  neutral,  for  they 
/can  be  neither  fast  nor  slow,  since  there  is  no  distinction  between 
longitudinal  and  transverse  directions. 

The  determination  of  the  character  of  sections  in  a  rock-slice 
enables  us  to  form  a  conclusion  as  to  the  character  of  the  mineral 
as  a  whole. 

In  a  uniaxial  crystal  the  character  of  all  sections  is  the  same 
.as  the  character  of  the  mineral,  which  is  that  of  its  optic  axis. 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      621 

In  a  biaxial  crystal  the  character  of  the  greater  number  of 
sections  is  the  same  as  that  of  the  mineral,  which  is  that  of  its 
acute  bisectrix.  The  smaller  this  angle  the  more  frequently 
the  character  of  sections  coincides  with  that  of  the  mineral. 

A  section  with  pendulum  movement  and  higher  relative  retarda- 
tion than  most  other  sections  of  the  same  mineral  with  the  same 
thickness  will  always  have  the  same  character  as  the  mineral  itself. 

A  pseudosymmetric  section  indicates  that  the  crystal  is  neutral, 
in  other  words,  that  its  optic  axial  angle  is  90°,  but  only  certain 
sections  of  a  neutral  crystal  are  pseudosymmetric,  and  other 
neutral  sections  do  not  necessarily  belong  to  a  neutral  crystal. 

The  character  of  the  longitudinal  direction  is  best  ascertained 
in  the  object-image  in  the  manner  already  described,  but  as  will 
be  seen  it  may  also  be  determined  from  the  directions-image 
itself. 

To  identify  the  longitudinal  direction  and  its  proximal  and 
distal  ends  in  the  sketch  of  the  object-image,  the  stage  should 
be  rotated  till  in  the  directions-image  the  central  isogyre  is  seen 
to  coincide  or  make  an  angle  of  less  than  45°  with  the  right  and 
left  cross-wire  and  have  its  proximal  end  to  the  right.  This 
may  be  termed  the  index  position  of  the  isogyre,  for  the  index 
reading  will  then  give  the  position  of  the  proximal  end  of  the 
longitudinal  direction  of  vibration. 

When  the  isogyre  is  in  the  index-position,  the  character  of  the 
longitudinal  direction  may  be  determined  by  inserting  a  gypsum 
plate  in  the  slot  (figs.  8  and  16).  If  this  be  done  the  isogyre  itself 
will  assume  the  colour  characteristic  of  the  plate,  but  will  be 
bordered  by  higher  colours  on  one  side  and  lower  colours  on  the 
other.  If  the  colours  are  lower  on  the  same  side  as  the  proximal 
end  of  the  slot,  the  character  of  the  longitudinal  direction  and 
therefore  of  the  isogyre  and  section  will  be  the  same  as  that  of  the 
direction  of  the  gypsum  plate  parallel  to  the  slot.  By  the 
proximal  end  of  the  slot  is  meant  of  course  that  nearest  the 
proximal  end  of  the  isogyre  and  of  the  longitudinal  direction  of 
vibration.  If  the  procedure  already  described  has  been  fol- 
lowed, this  will  be  the  right-hand  end.  If  the  colours  are  higher 
on  the  same  side  as  the  proximal  end  of  the  slot,  the  character 
of  the  section  will  be  opposite  to  that  of  the  direction  in  the 
gypsum  plate  parallel  to  the  slot. 

For  instance,  if  the  slot  be  in  the  position  indicated  in  figs.  8 


622      J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

and  16,  and  the  colours  be  lower  on  the  margin  of  the  isogyre 
farther  from  the  observer  as  in  those  figures,  the  character  of 
the  section  will  be  the  same  as  that  of  the  plate  parallel  to  the  slot. 

These  methods  apply  both  to  uniaxial  and  biaxial  crystals. 
The  inferences  that  can  be  drawn  from  the  characters  of  one  or 
more  sections  with  reference  to  that  of  the  mineral  have  already 
been  described  (pp.  620,  621). 

Sections  Perpendicular  to  an  Optic  Axis. — These  may  be  re- 
cognised in  the  object-image  by  the  darkness  in  all  positions  * 
in  a  uniaxial  mineral,  and  in  a  biaxial  mineral  by  a  feeble 
illumination  which  does  not  vary  when  the  stage  is  rotated. 
They  show  no  relative  retardation  and  are  therefore  neutral. 

If  a  gypsum  plate  be  inserted  in  the  slot  over  the  directions- 
image  of  such  a  section  of  a  uniaxial  crystal,  the  black  cross 
in  the  directions-image  will  be  represented  by  a  cross  of  the 
colour  characteristic  of  the  plate  ;  and  if  the  mineral  be  of  the 
same  character  as  the  direction  in  the  plate  parallel  to  the  slot, 
the  quadrants  through  which  the  slot  passes  will  show  higher 
colours,  and  the  other  quadrants  lower  colours,  while  if  it  be  of 
the  opposite  character,  the  contrary  will  be  the  case.  If  a  quartz 
wedge  or  mica  ladder  possessing  the  same  character  as  the 
mineral  be  pushed  progressively  in,  the  rings  of  colour  in  the 
former  quadrants  will  contract,  and  in  the  latter  will  expand,  and 
if  it  possess  the  opposite  character,  the  same  phenomena  will 
occur  in  the  alternate  quadrants. 

In  biaxial  crystals  cut  at  right  angles  to  an  optic  axis,  the 
isogyre  always  passes  through  the  centre,  and  has  two  distal  ends. 
In  certain  positions  it  is  straight  and  parallel  to  a  cross  wire  and 
lies  in  the  optic  axial  plane.  If  then  the  stage  is  rotated  through 
45°  towards  the  slot,  the  isogyre  becomes  a  branch  of  an  hyperbola 
with  its  axis  parallel  to  the  slot  (fig.  19).  If  a  gypsum  plate  be 
now  inserted,  the  hyperbolic  isogyre  will  show  the  interference 
colour  of  the  plate,  and  at  the  same  time,  if  the  crystal 
have  the  same  character  as  the  direction  in  the  plate  parallel 
to   the  slot,    the   concave   margin   will    exhibit   higher   colours 

*  Isotropic  crystals  will  also  be  dark  in  all  positions  in  the  object- 
image,  but  the  directions-image  will  show  a  uniformly  dark  field 
instead  of  a  cross,  unless,  as  sometimes  happens,  the  glass  of  the  ob- 
jective is  in  a  state  of  strain,  when  a  feeble  uniaxial  cross  may  be 
visible. 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      623 

(fig.  19),  while  the  convex  margin  will  exhibit  lower  colours. 
If  the  crystal  have  the  opposite  character,  the  reverse  will  be 
the  case.  The  amount  of  the  curvature  of  the  isogyre  in  this 
position  gives  some  idea  of  the  magnitude  of  the  acute  optic- 
axial  angle.  If  the  isogyre  be  straight,  the  angle  will  be  90° 
{fig.  18),  while  if  it  forms  a  right  angle  coinciding  with  two  arms 
of  the  cross  wires,  it  is  0°.  In  this  case  the  other  branch  of 
the  hyperbola  coalesces  with  it,  forming  the  cross  characteristic 
of  a  uniaxial  crystal  (fig.  21). 

A  very  rough  approximation  to  the  optic  axial  angle,  which 
may  be  employed  for  determinative  purposes,  may  be  obtained 
by  taking  the  angular  distance  6  round  the  circumference  of  the 
field  between  the  darkest  point  in  one  end  of  a  branch  of  the 
hyperbola  and  the  nearest  cross  wire,  and  doubling  it  (fig.  19). 
The  result  is  usually  too  high,  especially  for  medium  angles,  in 
which  the  error  may  amount  to  10°.  F.  Becke  has  shown  how 
a  much  more  accurate  result  may  be  obtained,*  and  a  still 
more  rigorous  procedure  is  described  by  F.  E.  Wright. f 

These  methods  may  be  applied  even  when  the  section  is  not 
exactly  at  right  angles  to  the  optic  axis,  if  the  point  of  emergence 
of  the  latter  appears  in  the  directions-image  (fig.  20).  Such 
sections  may  be  recognised  in  the  object-image  by  the  compara- 
tively low  relative  retardation. 

Sections  showing  a  Black  Cross  ivhich  breaks  up  on  Rotation  of 
the  Stage. — Unless  the  section  be  at  right  angles  to  an  acute 
bisectrix,  the  character  of  the  longitudinal  direction  of  vibration 
(see  p.  620)  will  be  that  of  the  crystal,  and  this  will  always  be  the 
case  if  the  section  shows  high  relative  retardation  compared  with 
most  other  sections  of  the  same  mineral  with  the  same  thickness. 
The  black  crosses  seen  in  sections  of  uniaxial  crystals  parallel  to 
the  optic  axis  and  of  biaxial  crystals  at  right  angles  to  the 
optic  normal  are  distinguished  by  the  rapidity  with  which 
they  break  up  and  leave  the  field  when  the  stage  is  rotated. 
Where  the  optic  axial  angle  is  small,  sections  at  right  angles  to 
the  obtuse  bisectrix  resemble  those  at  right  angles  to  the  optic 
normal. 

*  Min.  Petr.  Mitt.  {Tschermak),  vol.  xxiv.,  1905,  pp.  35-44;  Min. 
Mag.,  vol.  xiv.,  1907.  p.  280. 

j  American  Journal  of  Science,  Series  IV.,  vol.  xxiv.,  1907,  pp. 
332-341.      In  the  same  paper  other  methods  are  discussed. 


624     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

In  neutral  crystals  and  in  those  in  which  the  optic  axial  angle 
differs  but  slightly  from  a  right  angle,  the  optic  normal,  as  we 
have  seen,  shows  no  cross,  and  those  seen  in  sections  at  right 
angles  to  the  two  bisectrics  are  indistinguishable. 

If  the  optic  axial  angle  is  so  small  that  both  optic  axes  are 
visible  in  the  same  section,  the  methods  already  described  for  the 
case  where  one  optic  axis  is  present  may  be  employed  (fig  14). 

Variations  of  Relative  Retardation  in  a  Directions-Image. — There 
is  usually  a  decrease  in  the  relative  retardation  indicated  by 
the  interference  colours  towards  the  proximal  margin  or  margins 
of  the  field,  and  this  may  be  utilised  to  determine  the  position 
of  the  longitudinal  direction  and  its  proximal  end.  For  this 
purpose  the  stage  is  rotated  though  45°  from  the  position  of 
extinction.  Unless  an  optic  axis  is  visible,  the  isogyre  will 
then  have  passed  out  of  the  field  and  the  region  of  lowest 
interference  colours  will  mark  the  position  of  the  proximal  end 
of  the  longitudinal  direction  (fig.  12).  If  the  section  be  at  right 
angles  to  a  line  of  optical  symmetry,  there  will  -be  two  opposite 
regions  of  lowest  relative  retardation  (fig.  15),  and  the  line  joining 
them  will  be  the  longitudinal  direction.  This  method  is  fre- 
quently useful  where  the  isogyre  is  indistinct.* 

In  doubtful  cases  the  gypsum  plate  may  be  inserted,  and  then 
the  region  that  approximates  most  closely  to  the  colour  of  the 
plate  will  have  the  lowest  birefringence  and  indicate  the  prox- 
imal end  and  longitudinal  direction.  If  this  be  at  a  point  within 
45°  of  the  slot  and  the  colour  be  higher  than  that  of  the  plate, 
the  character  of  the  section  will  be  the  same  as  the  character 
of  the  plate.  If  it  be  more  than  45°  from  the  slot,  or  the 
colour  be  lower,  the  character  will  be  opposite  to  that  of 
the  plate.  If  both  these  conditions  hold  good,  it  will  be  the 
same  as  that  of  the  plate.  In  neutral  sections  the  lowest 
colour  will  be  about  45°  from  the  slot. 

If  the  optic  axis  be  in  the  field,  the  line  joining  it  to  the 
centre  will  be  the  longitudinal  direction.  Some  portions  of 
the  field  will  then  have  a  higher  and  others  a  lower  colour  than 
the  plate,  and  the  colour  in  the  centre  of  the  field  will  determine 
the  character  of  the  section,  unless  of  course  the  optic  axis  is  in 
the  centre  of  the  field,  when  the  character  will  be  neutral  (p.  622). 

Theodolite   Stage. — In   recent   years   Fedorov   has   introduced 
*  J.  W.  Evans,  Mia.  Mag.,   vol.  xiv.,  1907,  pp.  233-4. 


THE    MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      625 

the  *'  universal  "  or  theodolite  stage  by  means  of  which  the 
properties  of  light  vibrating  in  different  directions  may  be 
studied  in  parallel  light  in  the  object- image  of  a  single  section 
by  rotating  the  latter  on  two  or  more  axes.  The  subject  is, 
however,  too  extensive  to  be  considered  on  this  occasion. 

Other  Determinations. 

The  Thickness  of  the  Rock-slice. — The  only  practicable  method 
of  determining  the  thickness  of  an  ordinary  rock-slice  is  to  select 
a  known  mineral  whose  maximum  birefringence  is  practically 
constant  and  not  too  low,  such  for  instance  as  quartz,  orthoclase, 
olivine,  calcite  and  (for  approximate  results)  an  acid  or  inter- 
mediate plagioclase.  Search  is  then  made  for  the  section  of  this 
mineral  which  shows  the  highest  relative  retardation,  and  it 
may  be  assumed  that  its  birefringence  has  as  nearly  as  possible 
the  maximum  value.  Suppose  the  mineral  to  be  quartz,  with 
a  birefringence  of  9  millesims  (0'009),  and  the  greatest  relative 
retardation  observed  to  be  315  micro-millimetres.  Then  the 
thickness  of  the  section  will  be  315  -f-  9  =  35  microns. 

The  thickness  should  be  determined,  if  possible,  at  several 
points  so  as  to  obtain  an  idea  of  its  variation  in  different  parts  of 
the  rock-slice.  If  the  thickness  of  the  rock-slice  is  not  uniform, 
that  of  the  crystal  section  must  be  estimated  from  its  position 
in  the  slice  as  nearly  as  possible.  The  thickness  should  be  stated 
on  the  sketch,  and  indicated  by  the  depth  of  the  scale  (fig.  1). 
]f  the  thickness  is  not  uniform,  the  amount  of  variation  may 
be  indicated  in  the  same  way. 

Determination  of  the  Birefringence. — Knowing  the  thickness  of 
a  crystal  section  and  its  relative  retardation,  we  are  able  to 
determine  its  birefringence  by  dividing  the  latter  by  the  former. 
For  instance,  if  the  section  has  a  relative  retardation  of  340 
micro-millimetres  and  a  thickness  of  28  microns,  the  birefringence 
will  amount  to  340  -j-  28  =  12  millesims  or  0*012. 

A  number  of  different  crystals  of  the  same  mineral  are  dealt 
with  in  this  matter,  and  it  may  be  assumed  that  the  maximum 
birefringence  thus  obtained  falls  but  little  short  of  the  maximum 
birefringence  of  the  mineral. 

The  Refractive  Index. — A  knowledge  of  the  index  of  refraction 
of  a  mineral  is  a  valuable  means  of  recognition.     In  the  case 

Journ.  Q.  M.  C,  Series  IT. — No.  77.  35 


626     J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

of  a  thin  section  in  a  rock-slice  only  relative  determinations  of 
refractive  indices  are  possible  in  an  ordinary  petrological  micro- 
scope, comparison  being  made  either  with  the  Canada  balsam 
or  other  medium  in  which  the  rock-slice  is  immersed,  or  with 
an  adjoining  crystal. 

For  the  Becke  method  a  high  power  is  employed,  and  the 
cone  of  illumination  is  narrowed.  This  may  be  effected  by 
removing  or  lowering  the  condenser  and  inserting  a  card- 
board slip  with  a  hole  one  or  two  millimetres  in  diameter 
twenty  or  thirty  millimetres  below  the  stage.*  A  slit  of  the 
same  diameter  parallel  to  the  boundary  of  the  section  may  be 
substituted.  This  is  equally  effective  and  does  not  cut  down  the 
light  to  the  same  extent.  The  boundary  surface  between  the 
section  and  the  medium  or  adjoining  crystal  must  be  at  right 
angles  to  the  surface  of  the  rock-slice.  This  can  be  verified  bv 
observing  if  it  remains  constant  in  position  when  the  focus  is 
varied. 

If  now  there  be  an  appreciable  difference  between  the  re- 
fractive indices  on  opposite  sides  of  the  boundary,  one  margin 
of  the  boundary  will  usually  be  seen  to  be  lighter  than  the  field 
in  general  and  the  other  darker.  If  the  objective  be  focused 
on  a  point  in  the  neighbourhood  of  the  upper  surface  of  the 
section,  the  light  margin  of  the  boundary  will  be  on  the  side 
with  the  higher  refractive  index  and  the  dark  margin  on  that 
with  the  lower  refractive  index.  If  the  focus  be  gradually  lowered, 
these  bands  will  be  reversed  in  position. 

In  this  way  it  is  possible  to  determine  whether  the  refractive 
index  of  a  crystal  mounted  in  Canada  balsam  is  higher  or  lower 
than  that  of  this  substance.  If,  however,  the  crystal  is  un- 
covered, and  its  margin  free  from  balsam,  it  may  be  immersed 
in  a  succession  of  films  of  liquid  of  different  refractive  indices 
and  its  refractive  index  thus  determined  between  comparatively 
narrow  limits. 

If  the  crystal  section  be  birefringent  the  observation  should 
be  made  with  the  lower  nicol  in  position,  and  first  one  and  then 
the  other  direction  of  vibration  in  the  crystal  should  be  brought 
into  parallelism  with  the  direction  of  vibration  in  the  lower  nicol. 
In  this  way  the  indices  of  refraction  parallel  to  both  directions 
of  vibration  may  be  determined. 

*  An  iris  diaphragm  is  often  provided,  and  is  more  convenient. 


THE   MICROSCOPE   BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      627 

If  the  directions  of  vibration  of  adjoining  crystal  sections 
are  parallel,  exact  comparison  of  the  refractive  indices  corres- 
ponding to  each  pair  of  parallel  directions  may  be  carried  out 
in  the  same  manner.  In  other  cases  parallel  nicols  should  be 
employed  and  the  stage  rotated  till  their  direction  of  vibration 
bisects  the  angle  between  the  directions  of  the  pairs  of  vibration 
the  refractive  indices  of  which  are  to  be  compared.  In  all 
cases  a  comparison  of  the  mean  refractive  indices  may  be  made 
by  dispensing  with  the  use  of  a  nicol. 

If  a  crystal  or  grain  be  immersed  in  Canada  balsam  or  other 
medium,  such  as  a  highly  refracting  liquid,  or  a  larger  crystal, 
the  relation  between  its  refractive  index  and  that  of  the  sur- 
rounding material  may  be  determined  by  the  Schroder  van  der 
Kolk  or  "  finger '  method.  A  condenser  is  employed  and 
placed  close  below  the  object,  or  the  effects  will  be  reversed. 
One  side  of  the  illumination  is  then  shaded,  usually  by  the 
finger  placed  below  the  lower  nicol.  If  a  shadow  appear  on 
the  same  side  of  the  object  as  the  ringer  is  placed,  the 
refractive  index  of  the  object  is  higher  than  that  of  the 
medium.  If  it  appear  on  the  opposite  side,  the  refractive 
index  is  lower  than  that  of  the  medium.  By  means  of  a  nicol 
the  two  directions  of  vibration  can  be  separately  examined  in  the 
manner  already  explained. 

With  monochromatic  light  this  method  gives  good  results. 
It  is  usual  to  provide  a  series  of  liquids,  the  refractive  indices 
•of  which  differ  by  small  amounts,  starting  from  about  1*47 
and  extending  up  to  1*76,  afforded  by  methylene  iodide,  or  1*83 
by  a  solution  of  sulphur  in  methylene  iodide,  which  is,  however, 
not  so  satisfactory.  If  an  exact  determination  be  required,  a 
mixture  of  two  liquids  is  prepared,  which  has  as  nearly  as  possible 
the  same  refractive  index  as  the  mineral,  and  the  index  of  refractive 
of  this  mixture  is  determined  by  the  Abbe  refractometer.  It  is 
important  to  remember  that  the  refractive  indices  of  liquids 
change  considerably  with  the  temperature. 

If  white  light  be  employed,  the  phenomena  are  complicated 
by  the  fact  that  the  dispersion  of  the  colours  in  liquids  is  usually 
much  greater  than  with  solids  of  the  same  refractive  index,  and 
a  series  of  colour  phenomena  may  result,  which  complicates  the 
observation.  In  the  case  of  minerals  with  decidedly  higher  or 
lower  refractive  indices  than  the  medium  there  is  no  difficulty  ; 


628      J.  W.  EVANS    ON    THE    DETERMINATION    OF    MINERALS    UNDER 

hut  if  the  mineral  has  about  the  same  refractive  index  for 
blue  light  as  the  medium,  but  a  higher  refractive  index  for 
red  light,  only  the  red  light  will  be  obscured  on  the  same  side 
as  the  finger,  so  that  the  shadow  will  have  a  bluish  tinge. 
When  all  the  refractive  indices  of  the  mineral  are  included 
between  the  extreme  indices  of  the  medium,  there  will  be 
a  bluish  colour  on  the  finger  side  and  a  yellowish-red  one 
on  the  opposite  side ;  and  when  the  red  refractive  indices  are 
the  same  but  the  blue  refractive  index  of  the  medium  is  greater, 
there  will  be  a  red  shade  on  the  far  side.  The  colours  obtained 
with  particular  liquids  are  sometimes  very  characteristic  of 
minerals,  and  may  thus  be  employed  for  their  identification. 

All  the  particulars  obtained  in  the  investigation  of  the  mineral 
sections  should  be  embodied  in  the  sketch  as  shown  in  fig.  1. 

The  following  is  a  brief  abstract  of  the  procedure  in  the  detailed 
examination  of  the  optical  characters  of  a  mineral. 

A.  Examination  of  the  object-image. 

1.  With  stage  in  the  zero  position,  sketch  the  mineral  and 
indicate  the  positions  of  0°,  90°,  180°  and  270°  by  short  lines 
directed  inwards  from  the  circumference  (p.   601). 

2.  Determine  the  positions  of  edges,  cleavages  and  other 
rectilinear  directions  in  the  mineral  and  indicate  them  by  dis- 
continuous lines  through  the  centre,  each  distinguished  by  its 
two  index  readings  (p.  601). 

3.  Determine  the  extinctions  or  directions  of  vibration  and 
show  them  as  continuous  lines  through  the  centre  with  index 
readings  (pp.  601-604). 

4.  Note  the  absorption  colours  and  other  phenomena  shown 
by  light  vibrating  in  these  directions  (p.  604). 

5.  Determine  the  character  of  the  directions  of  vibration 
and  the  amount  of  relative  retardation  (pp.  604-613). 

B.  Examination  of  the  directions-image. 

6.  Determine  the  longitudinal  direction  and  its  proximal 
end,  and  deduce  the  character  of  the  section,  noting  at  the 
same  time  the  nature  of  the  movement  of  the  isogyre  and  any 
special  features  in  the  directions-image  (pp.  617-624). 

All  the  above  observations  should  be  made,  if  possible,  without 
moving  the  object.  If  any  movement  be  necessary,  it  should 
be  made  without  changing  the  orientation.  This  is  best  effected 
bv  the  use  of  a  mechanical  stage. 


THE   MICROSCOPE  BY  MEANS  OF  THEIR  OPTICAL  CHARACTERS.      029 

C.  Observations  extending  to  other  crystals  of  the  same 
mineral  and  other  minerals. 

7.  Determine  the  thickness  of  the  rock-slice  and  calculate 
the  birefringence  of  the  mineral  under  examination  (p.  625). 

8.  By  determining  the  character  of  other  sections  of  the  same 
mineral  or  of  those  showing  special  features,  determine  that  of 
the  mineral  itself  (pp.  620-624). 

9.  Determine  the  refractive  index  of  the  mineral  as  far  as 
circumstances  permit  (pp.   625-628). 

EXPLAXATIOXS     OF    FIGURES. 

Fig.  1.  Crystal  section  in  the  position  in  which  it  is  originally 
drawn  with  index-reading  zero.  Most  of  the  details 
shown  are  subsequently  added.  The  directions  of 
extinction  are  represented  by  thick  lines,  crystallo- 
graphic  directions  by  interrupted  lines,  and  the  posi- 
tion of  the  cross  wires  only  by  short  thick  lines. 

,,  2.  Crystal  section  with  the  long  edge  and  cleavage  parallel 
to  the  right  and  left  cross  wire.  The  index-reading 
83°  is  shown  on  the  right  end.  The  directions  which 
originally  coincided  with  the  cross  wires  are  shown 
by  short  thick  lines.  The  actual  cross  wires  are  re- 
presented here  and  in  fig.  3  by  thin  continuous  lines. 

,,  3.  Crystal  section  with  the  fast  (  —  )  direction  of  vibra- 
tion parallel  to  the  slot.  The  quartz  wedge  is  inserted, 
and  shows  a  black  band  where  it  exactly  neutralises 
the  crystal.  The  smaller  figures  in  the  scale  on  the 
wedge  indicate  hundreds,  the  larger  thousands  of 
micro-millimetres  of  relative  retardation. 

,,      -i.    Double  quartz  wedge. 

,,      5.    Combination  gypsum  plate  and  quartz  wedge. 

,,      6.    Mica  steps. 

7.  Straight  central  isogyre  showing  only  one  branch. 
The  inner  arrows  give  the  directions  in  which  the 
ends  of  the  isogyres  would  move  if  the  stage  were 
rotated  in  the  direction  of  the  outer  arrows. 

,,  8.  The  same  with  gypsum  plate  inserted.  The  lower 
colours  on  the  farther  side  of  the  isogyre  show  that 
the  character  of  the  section  is  fast  (  —  ). 


630      J.    W.    EVANS    ON    THE    DETERMINATION    OF    MINERALS. 

Fig.    9.    Pendulum  movement  obtained  by  rotation  from  fig.  7. 
,,    10.    Fan  movement  from  fig.  7. 
,,    11.    Parallel  movement  from  fig.  7. 
,,    12.    Fig.  7  rotated  through  45°.     The  lower  colour  in  the 

north-east  indicates  the  longitudinal  direction  and  its 

proximal  end. 
,,     13.    Straight  central  isogyre  of  two  branches  meeting  in  a 

black  cross  in  a  biaxial  crystal. 
,,     14.    The  same  rotated  through  45°  with  the  vertices  of  the 

isogyre  still  visible  in  the  field.     The  gypsum  plate  is 

inserted,  and  the  lower  colours  on  the  concave  sides 

of  the  curves  show  the  crystal  to  be  slow  (  +  ). 
,,    15.    Fig.   13  rotated  through  45°  in  a  case  in  which  the 

vertices  of  the  isogyre  have  disappeared.     The  lower 

colours  indicate  the  longitudinal  direction. 
,,     16.    Curved  central  isogyre  with  gypsum  plate.     The  lower 

colours  on  the  farther  side  of  the  isogyre  indicate  that 

the  section  is  fast  (  —  ). 
,,     17.    Section  at  right  angles  to  one  of  the  optic  axes  of  a 

biaxial  mineral.     The  optic  axial  plane  lies  east  and 

west. 
,,     18.    The  same  rotated  through  45°  when  the  crystal  is  neutral. 
,,     19.    The  same  when  the  crystal  is  not  neutral.     The  gypsum 

plate  is  inserted,  and  the  higher  colours  on  the  concave 

side  of  the  curve  show  that  the  crystal  is  fast  (  —  ). 
,,    20.    The  same  with  smaller  optic  axial  angle  showing  two 

branches  of  the  isogyre. 
,,    21.    Section  at  right  angles  to  the  optic  axis  of  a  uniaxial 

crystal — that  is  to  say,  one  in  which  the  acute  optic 

axial  angle  is  zero.     The  higher  colours  in  the  angles 

traversed  by  the  slot  and  plate  show  that  the  crystal 

is  fast  (— ). 

The  directions  of  the  arrows  in  figures  showing  isogyres  in- 
dicate the  relations  between  the  angular  directions  of  the  move- 
ments of  the  ends  of  the  isogyre  and  that  of  the  rotation  of  the 
stage,  and  their  lengths  the  relative  angular  velocities. 


Journ.  Quekett  Microscopical  Club,  Ser.  2,  Vol.  XII.,  No.  11,  November  1915. 


Jo  urn.  Q.  M.  C. 


Ser.  2,  Vol.  XII.,  PI.   35. 


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Determination  of  Minerals. 

(By  permission  of  the  Geologists'  Association.) 


Journ.  Q.  M.  C. 


Sim-.  2,  Vol.   XII.,  PL   36. 


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Determination  of  Minerals. 

(By  permission  ot  the  Geologists'  Association.) 


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Ser.  2,   Vol.  XII,  PL  37. 


Determination  of  Minerals. 

(By  permission  of  the  Geologists'  Association.) 


631 


ON    FIVE   NEW   SPECIES   OF  THE   GENUS 
HABROTROCHA. 

By  David  Bryce. 
{Read  October  26th,  1915.) 

Plates  38  and  39. 

In  the  following  paper  I  describe  five  new  species  of  pellet- 
making  Rotifera,  which  are  to  be  added  to  the  already  important 
genus  Habrotrocha.  The  first  two,  H.  insignis  and  H.  sylvestris, 
may  be  said  to  belong  to  the  central  group  of  the  genus,  being 
closely  related  to  H.  angusticollis  (Murray),  which  has  been 
designated  as  type  species  by  Woodcock.*  The  characteristics 
of  this  central  group  consist  of  a  relatively  long  and  slender 
head  and  neck,  a  middle  body  distinctly  stouter,  and  an  exceed- 
ingly short  foot,  together  with  rather  narrow  trochal  disks  borne 
on  somewhat  high  pedicels  usually  adnate.  H.  insignis  has 
other  more  special  characteristics,  one  of  which  has  not  been 
seen  in  any  other  Bdelloid.  The  upper  lip,  when  closely  exam- 
ined, is  found  to  have  a  curious  stiffening,  apparently  that  it 
may  better  support  the  slender  pedicels  under  the  strain  of 
the  lashing  cilia  above.  This  stiffening  is  not  very  obvious, 
but  once  observed  is  readily  recognised  and  can  be  detected  even 
when  the  corona  is  retracted  within  the  mouth. 

A  second  interesting  structure  is  the  looping  of  the  gullet  in 
a  certain  position  of  the  body.  A  similar  structure  has  been 
already  noted  by  Zelinka  for  Habrotrocha  Leitgebii,  and  it  is  also 
present  in  two  of  the  other  new  species,  viz.  U.  sylvestris  and 
H.  flava.  The  looping  of  the  gullet  is  one  of  several  structural 
modifications  that  are  distinctly  connected  in  their  origin  with 
the  attitude  assumed  by  the  rotifer  when  it  is  feeding.  There 
are  some  Bdelloids  of  the  family  of  the  Philodinidae  which  feed 
without  attempting  to  extend  themselves,  but  others  extend 
themselves  habitually  to  the  utmost,  without  doubt  in  order  to 
*  Woodcock,  Int.  Cat.  Set.  Lit.,  vol.  x.,  1911.     Zoology,  vi.  p.  45. 


632  DAVID    BRYCE    ON   FIVE    NEW    SPECIES    OF 

gather  food  from  the  increased  area  thereby  brought  within 
the  influence  of  the  vortices  set  up  by  the  cilia  of  the  trochal 
disks.  This  habit  of  extension  for  the  purpose  of  increasing  the 
food  supply  reacts  in  two  different  ways  upon  the  structure  of 
the  body.  One  of  these  is  very  apparent  in  such  species  as 
Rotifer  vulgaris  and  its  nearer  relatives,  where  the  foot  and  the 
rump  segments  have  become  so  elongated  that  they  constitute 
quite  a  large  proportion  of  the  whole  length  of  the  animal. 

In  the  central  section  of  the  Habrotrochae  the  head  and  neck 
are  lengthened  to  a  marked  extent,  whilst  the  rump  and  foot 
segments,  and  especially  the  latter,  become  or  remain  relatively 
short  and  unimportant.  The  neck  frequently  becomes  so 
slender  that  the  mastax  is  pushed  backwards  into  the  last  seg- 
ment of  the  neck  when  the  animal  is  crawling,  and  into  the 
anterior  segment  of  the  trunk  or  central  body  when  it  is  feeding. 
The  increasing  distance  from  the  mouth  to  the  mastax  necessi- 
tates in  turn  a  longer  gullet,  which  is  fully  but  not  tensely 
stretched  out  when  the  animal  displays  its  corona.  When  the 
latter  is  withdrawn,  the  inversion  of  the  mouth  reduces  the 
distance  to  the  mastax,  and  the  connecting  gullet  becomes  slack. 
In  extreme  cases  the  slackness  is  so  great  that  the  gullet,  which 
is  usually  a  little  stouter  near  the  mastax,  bends  over,  just  above 
the  stouter  part,  towards  the  ventral  side,  and  so  forms  a  loop, 
which  is  not  straightened  out  until  the  corona  is  again  everted. 
It  is  very  difficult  to  see  the  loop  distinctly.  The  animal  must 
be  observed  in  side  view  and  at  the  moment  when  the  neck  is 
fully  extended,  for  the  gullet  is  not  truly  "  looped  "  if  it  straightens 
out  before  the  eversion  of  the  corona. 

In  some  species  a  further  modification  is  seen.  Not  only  is 
the  mastax  shifted  rearwards,  but  also  the  brain,  which  is  nor- 
mally so  placed  that  the  narrow  anterior  end  is  close  to  the 
dorsal  antenna,  while  the  broader  posterior  part  more  or  less 
overlaps  the  mastax.  In  II.  insignis  the  anterior  end  of  the 
brain  is  placed  about  one-half  the  brain-length  behind  the 
antenna,  and  this  also  is  best  seen  in  lateral  view.  I  find 
that  this  modification  of  the  position  of  the  brain  does  not 
obtain  in  all  the  slender-necked  Habrotrochae,  and  it  seems 
therefore  to  be  a  character  useful  for  the  differentiation  of 
such  species. 

Habrotrocha  insignis,  again,  is  one  of  the  few  species  of  Bdelloid 


THE    GENUS    HABROTROCHA.  633 

Kotifera  which  not  only  can  endure  life  in  the  most  exposed 
situations,  but  which  even  seems  to  prefer  it.  It  would  be 
difficult  in  Great  Britain  to  find  mosses  growing  in  bleaker 
places  than  on  the  tops  of  the  Scottish  and  Welsh  mountains, 
yet  wherever  in  such  elevated  places  mosses  can  be  found  growing 
and  braving  the  storms,  this  species,  sheltering  in  the  moss-tuft-;, 
seems  able  to  flourish  exeeedinsiv  well. 

In  many  respects  the  new  species  Habrotrocha  sylvestris  is 
closely  allied  to  H.  insignis,  but  the  upper  lip  is  not  so  high,  and 
lacks  the  curious  stiffening  so  distinctive  in  the  latter.  On  the 
other  hand  H.  sylvestris  has  a  unique  character  of  its  own.  In 
certain  Distylae  (for  example,  D.  depressa)  the  lower  end  of  the 
oesophagus  (which  seems  to  project  into  the  stomach  cavity) 
has  an  incessant  undulatory  movement.  I  found  a  similar 
movement  of  the  oesophagus  in  H.  sylvestris,  where  it  has  pro- 
bablv  some  connection  either  with  the  formation  of  the  food- 
pellets  or  with  their  discharge  into  the  stomach. 

Both  H.  insignis  and  H.  sylvestris  are  probably  of  near  relation- 
ship to  H.  tridens  (Milne),  which,  however.  I  judge,  from  the 
description  and  figure  given,  to  be  an  altogether  more  slender 
and  cylindrical  animal  than  either.  I  have  not  been  able  to 
identify  it  with  certainty. 

The  third  species  described,  Habrotrocha  pavida,  is  of  quite  a 
different  type,  and  is  notable  for  its  moderately  wide  corona, 
and  the  bulging  lateral  margins  of  the  mouth,  which  give  it  a 
very  characteristic  outline  when  favourably  seen.  Although  it 
has  been  known  to  me  for  many  years,  it  has,  with  one  exception, 
only  been  found  in  moss  growing  among  the  grass  in  a  small 
suburban  garden.  It  is  a  very  timid  species,  and  will  rarely 
feed  unless  it  is  ensconced  in  a  convenient  '  heap  '  of  sand  or 
debris,  from  which  it  protrudes  its  head  "  at  mealtimes."  In 
an  earlier  paper  *  I  have  described  the  manner  in  which  the  food- 
pellets  are  moulded  in  the  case  of  H.  constricta  (Dujardin).  In 
H.  pavida  there  is  a  little  more  elaboration  of  the  process.  If  a 
good  lateral  view  can  be  obtained  while  the  animal  is  feeding, 
the  greater  part  of  the  oesophagus  can  be  seen,  albeit  somewhat 
indistinctly.  The  inner  surface  of  the  tube  is  apparently  lined 
with  cilia,  for  there  is  an  almost  continuous  undulatory  move- 

*  Bryce,  "  Further  Xotes  on  Macrotrachelous  Callidinae,"  Jourri. 
Quek.  Micr.  Club.,  Vol.  V.,  Ser.  II.,  pp.  436-155.     Xo.  35,  1894. 


634  DAVID    BRYCE    ON    FIVE    NEW    SPECIES    OF 

ment  carrying  along  the  food  particles  towards  the  end  farther 
from  the  mastax.  Arrived  near  that  end,  they  become  incor- 
porated in  a  pellet,  which  is  revolved  at  moderate  speed  until 
it  is  large  enough  to  be  expelled  into  the  wide  stomach,  where 
its  revolving  motion  ceases.  The  growth  of  the  pellet  at  its 
beginning  could  not  be  seen,  but  perhaps  a  minute  or  so  after 
the  expulsion  of  one  pellet  there  could  be  discerned  a  tiny  mass 
which,  revolving  slowly,  gradually  increased  in  bulk,  the  whole 
process  lasting  from  five  to  ten  minutes  if  the  animal  continued 
feeding  steadily.  The  undulatory  movement  of  the  oesophagus 
seemed  to  be  similar  to  that  frequently  observable  in  the  gullet, 
and  less  violent  than  that  of  the  oesophagus  in  //.  sylvestris,  and, 
further,  it  seemed  to  cease  if  no  particles  of  food  were  being  passed 
along,  just  as  it  does  in  the  gullet. 

Like  all  the  foregoing  species,  Habrotrocha  flava,  sp.  nov.,  is  a 
dweller  in  ground  moss,  although  on  one  occasion  I  found  it  in 
moss  which  had  been  growing  on  a  roof,  but  becoming  detached 
had  rolled  into  the  roof  gutter.  It  is  a  brightly  coloured  species, 
for  whilst  the  whole  body  in  the  adult  is  distinctly  yellowish, 
the  colour  of  the  stomach  deepens  almost  to  a  bright  rust-red. 
The  corona  has  a  somewhat  unusual  structure  which  I  later 
describe  in  detail,  and  the  many-toothed  rami,  the  stout  foot 
and  wide  separation  of  the  spurs  make  this  an  easily  recognisable 
species. 

A  very  different  habitat  is  characteristic  of  Habrotrocha  longula 
sp.  nov.,  which  shows  a  preference  for  mosses  and  algae,  growing 
in  running  water  in  the  more  mountainous  districts,  where  it  is 
constantly  found  in  company  with  Philodina  flaviceps  Bryce 
and  Philodinavus  paradoxus  (Murray),  which  also  delight  in  such 
situations.*  This  species  has  the  same  habit  as  H.  pavida  of 
taking  shelter  in  any  available  aggregations  of  sand  or  debris. 
The  stomach  in  adult  examples  is  usually  vividly  coloured  in 
tints  of  pinkish  red.  Its  elongate  form,  short  foot,  and  peg- 
like spurs,  held  nearly  parallel,  seem  to  show  relationship  to 

*  I  have  occasionally  met  with  a  form  nearly  related  to  H.  longula, 
perhaps  identical  with  it,  in  submerged  confervae  or  mosses  growing 
upon  artificially  made  edges  of  town  ponds  and  in  watercress  in  a 
country  ditch,  but  I  have  not  had  the  opportunity  of  comparing  any 
of  the  few  examples  thus  found  with  my  notes  or  sketches  of  the  form 
now  described. 


THE    GENUS   HABROTROCHA.  635 

//.  clegans  (Milne),  which,  however,  has  a  narrower  corona  and 
a  still  shorter  foot. 

Habrotrocha  insignis,  sp.  nov. 
PI.  38,  fig.  1. 

Specific  Characters. — Head  and  neck  long,  slender  ;  trunk 
much  stouter  ;  foot  very  short.  Corona  narrow,  three-fourths  of 
collar  width  ;  disks  dorsally  canted  and  separated  by  notch  ; 
pedicels  rather  high,  slender,  adnate.  Upper  lip  undivided,  rising 
nearly  as  high  as  pedicels,  centrally  rounded,  stiffened  by  rigid 
bent  rod  of  staple-like  outline.  Mastax  far  back  ;  rami  with 
three  teeth  each.  Gullet  long  and  looped.  Brain  remote  from 
antenna.  Spurs  short,  acute  cones,  without  or  with  little  inter- 
space. 

When  crawling  this  species  bears  some  resemblance  to  Habro- 
trocha angusticollis  (Murray),  when  the  latter  is  seen  out  of  its 
case.  The  skin  of  the  long  head  and  neck  is  so  smooth  that  it 
has  a  somewhat  bright  and  tight  appearance.  That  of  the 
trunk  is  finely  punctate  or  stippled  along  the  longitudinal  skin- 
folds, which  are  distinctly  marked,  the  four  central  extending 
over  the  preanal  segment.  In  well-grown  examples  the  trunk 
is  somewhat  long  and  so  much  stouter  than  the  neck  as  to  give 
a  somewhat  swollen  appearance.  It  gradually  increases  in  size 
up  to  the  fourth  central  segment,  the  succeeding  preanal  seg- 
ment being  nearly  as  large,  and  the  anal  much  smaller,  and  so 
rapidly  diminishing  to  the  end  of  the  short  three- jointed  foot. 
The  slender  rostrum  has  rather  prominent  lamellae.  In  front 
of  the  antenna  is  seen  within  the  head  a  curious  structure,  which 
may  be  likened  to  a  thin,  rigid  rod  bent  into  the  form  of  a  staple, 
but  which  may  be  the  thickened  margin  of  a  concave  plate 
having  that  outline.  No  similar  structure  has  yet  been  detected 
in  any  other  species.  When  the  corona  is  protruded  this  bent 
rod  or  plate  is  seen  to  be  external  on  the  dorsal  side  of  the  upper 
lip.  The  points  of  the  uprights  are  now  directed  forwards 
(having  pointed  backwards  while  the  corona  wTas  hidden),  and 
the  closed  end  to  the  rear,  about  level  with  the  anterior  margin 
of  the  base  of  the  retracted  rostrum.  In  dorsal  view  the  uprights 
diverge  very  slightly,  the  points  reaching  the  anterior  edge  of 
the  upper  lip  on  each  side,  not  far  from  the  centre.     In  lateral 


636  DAVID    BRYCE    ON   FIVE    NEW    SPECIES    OF 

view  they  are  seen  to  be  curved  and  to  enclose  a  concave  area. 
Whether  bent  rod  or  plate,  the  structure  seems  to  be  a  support 
for  the  high  upper  lip,  and  indirectly  for  the  slender  pedicels. 
The  under  lip  is  only  moderately  prominent,  but  in  lateral  view 
the  sides  of  the  mouth  seem  rather  high.  Behind  the  mouth  I 
saw  several  faintly  marked  annular  plicae.  The  positions  of  the 
mastax  and  of  the  brain  and  the  looped  gullet  have  been  des- 
cribed above. 

The  short  foot  tapers  rapidly  and  is  about  equal  in  length  to 
one-sixteenth  of  the  whole  body.  On  the  dorsal  surface  of  the 
proximal  joint,  just  behind  the  anus,  is  a  strong  thickening  of 
the  hypodermic  skin,  conspicuous  in  lateral  view  when  the  animal 
is  extended.  When  feeding  most  of  the  foot  is  retracted  within 
the  body,  and  the  extremity  is  covered  by  the  rump.  When 
the  animal  is  crawling  there  is  no  slithering  movement.  The 
antenna  is  of  moderate  size. 

Like  many  of  its  near  relatives,  this  species  is  exceedingly 
timid.  When  it  ventures  to  display  its  corona  it  usually  adopts 
very  curious  positions.  A  favourite  position  is  attained  by  the 
animal  bending  the  head  and  neck  back  until  the  corona  nearly 
touches  the  rump,  and  then  turning  the  head  half  round  so  that 
the  corona  presents  a  lateral  and  inverted  view.  Poses  of  this 
character  are  frequently  seen  among  tube-dwelling  species  with 
long,  slender  necks,  and  it  would  not  be  surprising  if  H.  insignis 
should  later  be  found  to  belong  to  this  section,  although  no 
tube-dwelling  habit  has  yet  been  observed.  It  is,  of  course, 
equally  possible  that  it  may  have  been  a  tube-dwelling  species 
in  the  past. 

An  example  isolated  laid  eggs  of  usual  type,  oval,  smooth  and 
hyaline,  and  measuring  66  jx  x  46  /x. 

My  largest  examples  measured  about  290  \x  in  length,  the 
rami  15  //,,  the  spurs  4  to  5  $x  ;  the  corona  about  20  /x  wide, 
and  the  collar  about  26  fx. 

First  obtained  in  ground  moss  from  Baden  (?  Schwarzwald) 
in  1894,  and  thereafter  in  moss  collected  by  Mr.  D.  J.  Scourfield 
on  Cader  Idris  in  1895;  in  moss  from  the  top  of  Ben  Vrachie 
(Perthshire)  in  1908 ;  in  liverwort  collected  by  Mr.  G.  K. 
Dunstall  near  Lynton  (North  Devon)  in  1914,  and  in  rock  moss 
from  the  summit  of  Snowdon  (Wales),  gathered  by  Mr.  Lionel 
Bennett  in  the  same  year. 


THE    GENUS   HABROTROCHA.  637 

Habrotrocha  sylvestris,  sp.  nov. 
PI.  39  fig.  2. 

Specific  Characters. — Head  and  neck  slender,  elongate  ;  trunk 
much  stouter.  Corona  narrow,  disks  scarcely  separated,  much 
canted  to  dorsal  side ;  pedicels  adnate,  obliquely  truncate, 
hidden  in  dorsal  view  by  upper  lip,  which  rises  in  bold  curve 
nearly  to  edge  of  disks,  and  is  centrally  obtusely  angled  and 
moderately  deep.  Gullet  long,  looped.  Brain  close  to  antenna. 
Mastax  set  far  back  when  feeding.  Rami  with  two  and  three 
teeth  respectively.  Foot  short,  usually  hidden.  Spurs  short, 
acute,  conical,  slender,  divergent.  Oesophagus  with  constant  (?) 
undulating  movement. 

I  have  seen  only  some  five  or  six  examples  of  this  species, 
which  seems  to  be  closely  related  to  H.  angusticollis.  It  differs 
very  markedly  in  the  form  of  the  under  lip,  which  is  not  pro- 
duced into  a  spout-like  front,  but  simply  rounded  like  the  edge 
of  a  cup.  When  feeding,  a  few  annular  wrinkles  are  visible  on 
the  ventral  and  lateral  surfaces  of  the  head  about  the  level  of 
the  retracted  rostrum,  and  to  right  and  left  of  the  antenna  are 
two  minute  decumbent  processes.  The  animal  crawls  in  a  rather 
leisurely  fashion.  On  one  occasion  I  saw  a  rough  tube,  partly 
secreted,  partly  of  entangled  particles,  and  I  have  seen  eggs 
measuring  about  70  /x  x  40  ft,  of  normal  outline,  smooth  and 
hyaline. 

I  have  no  record  of  the  length  when  extended,  but  estimate  it 
about  220  //.  When  feeding ,  the  individual  figured  measured 
about  190  fx. 

Several  examples  were  found  in  ground  moss  collected  by 
Mr.  A.  W.  Sheppard  in  St.  Leonard's  Forest,  Horsham,  in  1909. 
Another  was  detected  in  moss  sent  me  by  Mdle.  Montet,  of 
Vevey,  Switzerland,  and  one  other  in  moss  from  the  Black  Forest, 
Baden,  which  the  late  Mr.  John  Stevens,  of  Exeter,  had  received 
and  kindly  shared  with  me. 

Habrotrocha  pavida,  sp.  nov. 

PL  38,  fig.  2. 

Specific  Characters. — Body  gradually  increasing  to  greatest 
width  near  rump,   thence  rapidly  diminishing  ;   foot  small,   of 


638  DAVID    BRYCE    ON   FIVE    NEW    SPECIES    OF 

three  joints,  hidden  except  spurs.  Corona  rather  wider  than 
collar,  pedicels  separated  by  moderate  sulcus.  Upper  lip  low, 
central  portion  slightly  produced  to  about  level  of  nexus  between 
pedicels,  rounded  and  undivided.  Sides  of  mouth  with  strong 
external  prominences.  Rami  obtusely  angled,  each  with  four 
teeth.  Spurs  slender,  acute,  held  nearly  parallel,  sometimes 
slightly  incurved,  decurved,  claw-like,  bases  separated  by  inter- 
space nearly  equal  to  spur  length.     Toes  three,  small,  conical. 

In  adults  the  whole  body  is  tinged  with  yellow,  and  some- 
times the  skin  is  slightly  viscous.  It  usually  attains  its 
greatest  width  in  the  hinder  part  of  the  fourth  central  segment, 
and  thence  narrows  rapidly  to  the  small  foot,  which  is  so 
hidden  beneath  the  rump  that  even  when  crawling  only  the 
spurs  can  be  seen  in  dorsal  view.  In  this  it  resembles  Habro- 
trocha  elegans  (Milne),  but  the  body  is  generally  stouter,  the 
increase  in  size  rearwards  more  marked,  and  the  spurs  are  not 
peg-like.  When  disturbed  it  crawls  about  very  actively.  The 
corona  is  wider  than  is  usual  in  the  genus,  exceeding  the  width 
of  the  collar.  This  is  not  obvious,  for  the  lateral  margins  of  the 
mouth  have  each  a  strong  rounded  external  prominence,  which 
are  visible  in  dorsal  view,  and,  being  exactly  at  the  level  of  the 
collar,  add  to  the  apparent  width  of  the  latter.  A  similar  effect 
has  been  seen  and  described  in  Calledina  angusta  Bryce,  and  I 
have  also  seen  it  in  Calledina  aculeata  (Milne),  but  in  these  species 
the  prominences  are  angular  and  rather  less  conspicuous.  The 
post-oral  segment  has  an  annular  thickening  of  the  skin,  rising 
to  small  bosses  at  right  and  left  of  the  base  of  the  antenna.  The 
neck  and  gullet  are  not  unusually  long,  and  the  brain  is  close 
behind  the  antenna.  The  rami  are  somewhat  triangular  in  out- 
line, and  have  each  four  well-marked  teeth.  When  feeding,  the 
foot  and  the  greater  part  of  the  rump  segments  are  usually  with- 
drawn or  hidden  beneath  the  trunk.  The  spurs  are  rather 
slender  and  acute,  held  almost  parallel,  the  inner  side  almost 
straight,  the  outer  slightly  curved,  somewhat  decurved  and 
claw-like,  and  have  their  bases  separated  by  a  moderately  wide 
interspace  ;  altogether  they  are  of  an  unusual  and  rather  dis- 
tinctive form. 

The    stomach    usually    contains    pellets    of    good    size.     The 
process  of  their  formation  has  been  described  above. 

This  very  distinct  species  seems  to  take  up  its  position  in 


THE    GENUS    HABROTROCTIA.  639 

the  leaf  axils  of  certain  small  ground  mosses,  and  to  gather 
round  it  an  accumulation  of  particles  within  which  it  shelters, 
and  possibly  thus  makes  a  tube  of  a  most  elementary  description. 
It  produces  eggs  of  broadly  ovate  form,  with  rather  obtuse  ends, 
shells  smooth  and  hyaline,  measuring  about  76  fj.  x  51  /i. 

Length,  extended,  about  270  // ;  feeding,  about  170  jx. 
Eami,  20  fx.     Spurs,  6  fx.     Width  of  corona,  38  p. 

Habitat. — Moss  among  short  grass  in  my  garden,  Stoke  New- 
ington,  and  (one  individual  only)  in  tree  moss  from  Norton's 
Heath,  Essex. 


Habrotrocha  flava,  sp.  now 
PL  38,  fig.  3. 

Specific  Characters. — Corona  spreading,  yet  little  wider  than 
collar.  Pedicels  high,  sub-adnate.  Upper  lip  undivided,  rising 
rather  high  to  rounded  tip.  Neck  moderately  long ;  gullet 
looped  ;  mastax  far  back  ;  rami  with  six  or  seven  teeth  each. 
Foot  very  short  and  stout ;  spurs  short,  strongly  decurved, 
widely  separated  and  diverging  ;    interspace  very  convex. 

A  species  of  moderate  size  with  several  distinctive  characters. 
"While  apparently  allied  to  the  long-necked  species  of  the  genus, 
the  head  and  neck  are  less  slender  than  is  customary  in  that 
section.  The  adults  are  frequently  conspicuous  from  the  vivid 
yellowish  red  of  the  stomach  and  the  paler  tint  of  the  remainder 
of  the  body.  The  corona  appears  to  be  of  unusual  type.  In 
place  of  the  pedicels  being  straight,  slightly  diverging  or  parallel 
columns,  they  seemed  to  be  separated  at  their  bases,  to  approach 
each  other  at  half  height,  and  thereafter  to  diverge  ;  the  inner 
line  of  each  showing  thus  a  bold  curve  in  dorsal  view.  Yet  they 
seemed  to  be  connected  by  a  delicate  membrane  from  their 
bases  to  near  the  plane  of  the  trochal  disks.  I  could  discern  on 
the  dorsal  line  an  unusually  faint  line  marking,  as  I  thought,  the 
•outline  of  a  very  delicate  upper  lip,  and  farther  back  in  front  of 
the  retracted  rostrum  a  much  stronger  line  moderately  curved 
crossing  the  head.  The  head  is  rather  elongate  when  the  corona 
is  displayed,  and  the  mastax  is  then  usually  in  the  first  and 
occasionally  in  the  second  trunk  segment.  The  gullet  is  long 
.and  is  looped  when  the  animal  is  not  feeding.     The  anterior  of 


640  DAVID    BRYCE    ON    FIVE    NEW    SPECIES    OF 

the  brain  is  a  little  way  behind  the  dorsal  antenna.  When 
feeding,  this  species  usually  conceals  the  whole  foot  below  the 
rump  segments.  The  foot  has,  I  think,  three  segments,  the 
second  somewhat  disk-like  and  carrying  two  widely  separated 
spurs,  which  in  dorsal  view  seem  to  be  short,  stout  cones,  but 
are  really  only  moderately  short  and  strongly  decurved.  The 
interspace  between  them  is  strikingly  convex,  and  about  12  \x 
wide.  Two  strong  and  broadly  truncate  toes  were  seen  re- 
peatedly ;  a  third  was  possibly  present,  but  not  detected.  On 
the  post-oral  segment  there  is  a  small  prominence  on  either 
side  of  the  short  antenna. 

Length,  320  /*.    Rami,  21  fx.    Corona,  23  //.  wide. 

In  ground  moss  at  Mundesley  and  roof  moss  at  Paston,  near 
Mundesley  ;  also  in  ground  moss  collected  by  Mr.  G.  K.  Dunstall, 
in  Surrey. 


Habrotrocha  longula,  sp.  nov. 
PI.  39,  fig.  1. 

Specific  Characters. — Rather  elongate  and  slender ;  body 
nearly  cylindrical ;  foot  very  short.  Corona  wider  than  collar  ; 
pedicels  separated  by  narrow  gap  ;  disks  slightly  canted  to  dorsal 
side.  Upper  lip  rising  to  moderately  high,  obtuse,  median  point. 
Brain  long,  anterior  close  to  antenna,  posterior  just  overlapping 
mastax.  Gullet  not  looped.  Rami  somewhat  triangular,  longish, 
each  with  five  teeth.  Spurs  short,  stout  pointed  cones,  held 
nearly  parallel. 

In  searching  washings  of  moss  or  algae  from  stones  in  swiftly 
running  streams  in  hilly  districts  or  near  the  shores  of  mountain 
lakes,  one  frequently  finds  this  species  in  numbers,  and  marching 
about  with  much  pertinacity,  though  not  with  much  speed.  It 
attracts  attention  by  its  bright  colour,  the  alimentary  tract  being 
frequently  of  a  vivid  orange-red  to  pink-red  tint,  and  the  re- 
mainder of  the  body  of  a  much  paler  shade.  If  left  undisturbed, 
the  various  individuals  take  shelter  after  a  time  in  convenient 
,l  heaps  "  of  particles,  or  of  "  floccose,"  and  will  presently  com- 
mence to  feed  and  so  settle  down  to  satisfy  their  healthy  appe- 
tites. I  have  sometimes  been  able  to  see  a  rudimentary  secre- 
tion of  a  case,  and  have  no  doubt  that  a  certain  amount  of 


THE    GENUS   HABROTROCHA.  641 

viscous  fluid  is  produced  in  some  such  way  to  bind  together 
the  sheltering  particles  or  fibres.  In  several  respects  this  rotifer 
has  marked  affinity  to  Habrotrocha  elegans  (Milne),  which  has  a 
similar  shelter-taking  habit.  But  the  head  and  the  corona  are 
larger  in  proportion,  the  foot  is  less  hidden  beneath  the  rump  ; 
the  spurs  are  stouter,  though  rather  like  in  style  and  pose,  and 
the  teeth  of  the  rami  are  five  in  number. 

When  feeding,  the  animal  usually  bends  the  anterior  part  of 
the  body,  protruded  from  the  "  shelter,"  to  one  side  or  the 
other,  or  even  backwards,  but  I  have  not  seen  any  extravagant 
contortions  of  the  neck.  It  lives  fairly  well  in  small  troughs,  and 
even  in  small  cells  I  have  kept  it  for  over  two  months. 

The  form  and  proportions  of  the  upper  lip  as  shown  in 
fig.  la  (PI.  39)  seem  rather  distinctive.  The  lateral  margins  of 
the  mouth  are  slightly  prominent,  but  less  so  than  in  //.  pavida. 
The  underlip  is  slightly  produced  and  spout-like.  In  one  case  I 
saw  the  pellets  being  formed  at  a  distance  of  about  15  /x  behind 
the  rami,  and  the  oesophagus  seemed  to  be  from  20  to  25  /x  long. 
The  pellets  made  are  small  to  moderate  in  size.  On  several 
occasions  the  rather  long  and  normally  placed  brain  seemed  to 
me  to  show  reddish  blotches  as  of  suffused  pigment,  but  I  failed 
to  detect  any  definite  eye-spots,  such  as  are  so  distinct  in  the 
cognate  Habrotrocha  collaris  Ehrbg.  When  apparently  fully 
protruded  the  dorsal  antenna  measured  about  19  /x.  In  the 
feeding  position  it  is  inclined  forwards,  almost  resting  against 
the  retracted  rostrum,  but  towards  the  tip  it  is  slightly  recurved. 

The  terminal  foot  joint  is  stout  at  the  base,  but  tapers  rapidly, 
and  on  two  occasions  I  have  seen  three  short,  stout,  truncate 
toes  protruded. 

The  eggs  are  laid  within  the  "  shelter  "  and  are  of  oval  outline, 
smooth  and  hyaline  ;  measuring  about  57-60  /x  in  longest,  and 
39-40  /x  in  shortest  diameter. 

Length,  300-350  /x.     Spurs,  6  /x.     Width  of  corona,  35-38  p. 

From   rock   moss   from   summit   of   Ben  Vrackie,  Perthshire 
(1907).     In  moss  close  to  a  waterfall  near  Milford,  South  Wales, 
collected  by  Mr.  G.  K.  Dunstall.     In    ncrustation  of  stones  from. 
Untersee,  and  in  mosses  from  Mittersee,  Lunz,  Austria,  sent  me 
by  Dr.  von  Brehm,  of  the  Lunz  Biological  Station  (1911-13). 


Jourx.  Q.  M.  C,  Series  II.— No.  77.  36 


642   david  bryce  on  new  species  of  the  genus  tiabrotrocha. 

Description  of  Plates  38  and  39. 

Plate  38. 

Fig.  1.    Habrotrocha    insignis,    sp.    no  v.,    dorsal    view,    feeding 

position,     x  590. 
,,    la.  Head  and  neck,  corona  displayed,  in  lateral  view,    x  590. 
,,    2.    Habrotrocha  pavida,  sp.  nov.,  dorsal  view,  feeding  position. 

x  590. 
,,    2a.  Same,  in  lateral  view,     x  590. 
„    26.  Rami,     x  1,180. 

,,    2c.  Foot,  showing  spurs  and  toes,     x  590. 
,,    3.    Habrotrocha  flava,  sp.  nov.,  dorsal  view,  feeding  position. 

X590. 
,,    3a.  Part  of  foot,  showing  spurs.     X  590. 

Plate  39. 

Fig.  1.    Habrotrocha  longula,   sp.    nov.,   dorsal   view,    extended. 

X590. 
,,    la.  Dorsal  view,  feeding  position,     x  590. 
,,    16.  Head  and  neck,  corona  displayed,  in  lateral  view,     x  590. 
,,    lc.  Rami,     x  1,180. 
,,    2.    Habrotrocha   sylvestris,    sp.    nov.,    dorsal    view,    feeding 

position,     x  590. 
,,    2a.  Head  and  neck,  corona  displayed,  in  lateral  view,     x  650. 
„    26.  Rami,     x  1,180. 
,,    2c.  Spurs,     x  590. 


Journ.  QuekeU  Microscopical  Club,  Her.  2,   Vol.  XII.,  No.  77,  November  L915. 


Journ.  Q.  M.  C. 


Ser.  2,  Vol.   XEI.,  PL   38. 


y~ 


1  4 

■   ■      ■  Yjf    ■ 


>  './  fMM  fit ; 


D.  Bkyce,  del.    ad  nai. 


lev 


New  Species  of  Habrotrocha. 


Jo  urn.  Q.  M.  C. 


Ser.  2.  Vol.  XII.,  PI.  39. 


4    / 


%. 


i  \ 

1 


Ac 


D.  Bryce,  A/,  a.i  nat. 


New  Species  oe  Habrotrocha. 


643 


NOTICES    OF    BOOKS. 

The  British  Freshwater  Rhizopoda  and  Heliozoa.  By 
James  Cash  and  George  Herbert  Wailes,  F.L.S.,  assisted  by 
John  Hopkinson,  F.L.S.,  F.Z.S.  8J  x  5|.  Vol.  I.  The  Rhizo- 
poda, Pt.  I.  x  +  150  +  32  pages,  16  plates.  8vo.  1905. 
Vol.  II.  The  Rhizopoda,  Pt.  II.,  xviii  +  168  +  32  pages,  16 
plates  and  frontispiece.  8vo.  1909.  Vol.  III.  The  Rhizopoda, 
Pt.  III.,  xxiv  +  156  -f-  50  pages,  25  plates  and  frontispiece. 
8vo.     1915.     The  Ray  Society.     Price  £1  17s.  6d.  net. 

It  is  with  great  pleasure  we  draw  attention  to  the  publication  of 
the  third  volume  of  the  above  work ;  this  completes  the  section 
devoted  to  the  British  Freshwater  Rhizopoda  with  the  exception 
of  about  forty  species  recorded  since  1909,  the  date  when  the 
second  volume  was  issued.  It  is  intended  to  include  descriptions 
and  figures  of  these  species  in  a  fourth  and  final  volume  which  will 
also  include  the  British  Heliozoa. 

From  a  short  history  of  this  work  at  the  commencement  of  the 
second  volume  we  learn  that  Mr.  Cash  passed  away  early  in  1909 
and  did  not  see  the  completion  of  that  volume.  We  must  con- 
gratulate the  Secretary  of  the  Ray  Society  in  securing  the  services 
of  such  a  competent  worker  as  Mr.  G.  H.  Wailes  to  complete  the 
work  left  unfinished  by  its  original  author,  the  third  volume 
which  has  just  been  published  being  by  him.  Mr.  Hopkinson  has 
provided  a  short  memoir  of  James  Cash.  Before  studying  the 
Rhizopoda  he  had  devoted  considerable  attention  to  Bryology, 
and  his  collection  of  drawings  and  specimens  has  been  presented 
to  the  Manchester  Museum.  When  he  first  turned  his  attention 
from  the  mosses  to  the  rhizopods  we  do  not  know,  but  in  1891  he 
read  a  paper  before  the  Manchester  Microscopical  Society  giving 
the  results  of  his  investigations  of  the  Rhizopoda  of  the  Manchester 
area  in  the  same  year.  This  paper  added  several  species  to  the 
British  list,  and  seems  to  have  revived  an  interest  in  the  fauna 
of  these  microscopic  creatures.  These  volumes  show  how  far 
that  interest  has  been  carried  and  cannot  fail  to  be  an  aid  and 
incentive  to  the  microscopist  in  making  further  records  of  the 


644  NOTICES    OF    BOOKS. 

rhizopodal  fauna  of  the  districts  in  which  they  reside.  In  this 
connection  it  may  be  remarked  that  with  the  exception  of  Loch 
Ness  not  one  of  the  larger  British  lakes  has  been  investigated  as 
to  the  rhizopodal  fauna  of  either  the  plankton  or  deposits,  a 
large  and  unworked  field  awaiting  investigation.  To  the  micro- 
scopist  desirous  of  working  in  this  interesting  department  of 
micro-fauna  we  may  draw  attention  to  two  papers  recently 
published:  (1)  Dr.  Eugene  Penard,  "Collection  and  Preser- 
vation of  Freshwater  Rhizopoda,"  Journ.  Q.M.C.,  Vol.  X., 
pp.  107-116;  (2)  G.  H.  Wailes,  "Notes  on  the  Structure  of 
Tests  of  Freshwater  Rhizopoda,"  Journ.  R.M.S.,  April,  1915, 
pp.  105-116,  2  plates. 

In  the  third  volume  of  The  British  Freshwater  Rhizopoda  there 
are  twenty-five  plates  from  drawings  made  by  Mr.  Wailes,  a 
larger  number  than  in  either  of  »the  previous  volumes.  Of 
these  eight  are  coloured,  and  their  beauty  cannot  be  too  highly 
praised.  Through  the  courtesy  of  the  Secretary  and  Council  of 
the  Ray  Society  we  are  able  to  present  our  members  with  a  copy 
of  Plate  XLIV.  The  uncoloured  plates  are  in  collotype,  and 
are,  we  think,  a  great  improvement  on  the  half-tone  reproductions 
which  appeared  in  the  previous  volumes.  The  frontispiece  to  this 
volume  is  a  particularly  interesting  one,  being  reproductions 
in»  collotype  of  photo-micrographs  from  preparations  made  by 
Dr.  Eugene  Penard,  of  Geneva. 

In  the  case  of  all  three  volumes  Mr.  John  Hopkinson  has  been 
responsible  for  the  synonymic  references,  and  the  amount  of  labour 
and  critical  insight  that  he  has  devoted  to  this  share  of  the  work 
can  only  be  fully  realised  by  one  who  has  done  similar  work. 
The  arrangement  of  the  references  in  this  volume  is  an  improve- 
ment on  that  of  the  two  previous  volumes. 

Description  of  Plate  40.* 

Paulinclla  chromatophora  Lauterborn.  Figs.  1,2:  Side  view 
and  transverse  section  of  an  active  individual,  x  1,500.  Fig.  3 : 
Process  of  division,  x  1,500.  Fig.  4 :  Nucleus,  x  2,000.  All 
after  Lauterborn . 

P.  chromatophora  var.  pulchella  (G.  S.  West)  Wailes.    Figs.  5,  6  : 

*  British  Freshwater  Rhizopoda,  Vol.  III.,  PI.  XLIV. 


Journ.  Q.  M.  C. 


Ser.  2,  Vol.  XII.,  PL   40, 


y 


8 


10 


w 


13 


11 


12 


Rhizopoda. 


NOTICES    OF    BOOKS. 


645 


Oral   and   side    views,    after    West,     x  750.     P.  chromatofhora 
Lauterborn.      Figs.    7.   8  :     Side   and   oral  views,  after  Brown. 
x  1,200. 
Lecythmm  hyalinum  Hertwig  and  Lesser.      Fig.  9:   Solitary 

active  individual.  Fig.  10:  Appearance  of  same  when  deprived 
of  air.  x  500.  L.  granulatum  (Schulze)  Hopkins.  Fig.  11  : 
Individual  distended  by  ingested  diatoms;  from  a  specimen 
stained  and  mounted  by  Dr.  Penard.      x  300. 

Diplophrys  archcri  Barker.     Fig.  12  :  Active  solitary  individual. 
.Fig.  13:  Process  of  tetrad  division,  after  Hertwig  and  Lesser, 
x  1,000.  '  , 


646 


THE   CLUB   CABINET. 

The  following  Slides  have  been  added  to  the  Cabinet  since 
October  1914  : 

Echinodermata. 

Presented  by  C.  J.  H.  Sidwell. 
N.  32.  Spicules  of  Plexaura  flexuosa. 

Rotifera. 

Presented  by  C.  F.  Rousselet. 

Series  21.     Typical  genera. 

Anuraea  aculeata  (Ehrenberg). 
Asplanchna  Brightwelli  (Gosse),  $  and  $. 
Brachionus  pala  (Ehrenberg). 
Cathypna  luna  (Ehrenberg). 
Euchlanis  hyalina  (Leydig). 
Hydatina  senta  (Ehrenberg),  <$  and  $. 
Lacinularia  socialis  (Ehrenberg). 
Metopidia  lepadella  (Ehrenberg). 
Notholca  scapha  (Gosse). 
Polyarthra  platyptera  (Ehrenberg). 
Rhinops  nitrea  (Hudson). 
Synchaeta  tremula  (Ehrenberg). 

Insecta. 

Presented  by  the  late  Prof.  E.  A.  Minchin. 

Series  22.  Anatomy  of  the  Rat  Flea  (Ceratophyllus  fasciatus). 
Twenty-four  Slides  of  dissections  of  the  nervous,  genital  and 
salivary  systems,  etc.,  with  descriptive  text  and  plates. 


THE    CLUB   CABINET.  647 

Mycetozoa. 
Presented  by  C.  H.  Huish. 

C.A.     1.  Arcyria  cinerea  (=  albida). 

2.  Arcyria  jerruginea. 

3.  Badhamia  rubiginosa,  var.  dictyospora. 

4.  Ceratiomyxa  jructiculosa  (=  mucida). 

5.  Diachoea  leucopoda  (=  elegans). 

6.  Dictydium cancellatum  (=  umbilicatum) . 

7.  Didymium  dubium. 

8.  Didymium  melanospermum  (=  jarinaceum). 

9.  Lamproderma  columbinum. 

10.  Physarum  contextum. 

11.  Physarum  viride. 

15.  Trichia  botrytis,  var.  latcritia. 

Musci. 

Presented  by  G.  T.  Harris. 

Classification  from  Dixon's  Student's  Handbook  of  BritishMosses, 
second  edition. 

D.A.     6.  Amblystegium  serpens. 

7.  Amblystegium  varium. 

8.  Barbula  lurida. 

9.  Barbula  rubella. 

10.  Barbula  tophacea,  peristome. 

11.  Barbula  unguiculata. 

12.  Barbula  unguiculata,  peristome. 

13.  Brachythecium  populeum. 

14.  Brachythecium  rutabulum,  var.  longisetum. 

15.  Brachythecium  rutabulum,  peristome  (opaque). 

16.  Brachythecium  rutabulum,  peristome. 

17.  Brachythecium  rutabulum,  leaves  of  type. 

18.  Brachythecium  velutinum. 

20.  Bryum  atro-purpureum,  var.  gracilentum. 

21.  Bryum  capillare,  peristome. 

23.  Bryum  pollens,  "  female  flower.' 

24.  Campylopus  flexuosus. 

25.  Catharinea  undulata,  peristome. 

26.  Ceratodon  purpureus. 


)5 


648  THE    CLUB    CABINET. 

D.A.  27.  Cryphaea  heteromalla,  leaves. 

28.  Cryphaea  heteromalla,  peristome  (opaque). 

29.  Dicranella  heteromalla. 

30.  Dicranella  rufescens. 

31.  Dicranella  varia. 

32.  Dicranum  majus,  leaves  to  show  pores. 

33.  Dicranum  scoparium,  peristome  (opaque). 

34.  Dicranum  scoparium,  peristome. 

35.  Eurhynchium  confertum. 

36.  Eurhynchium  myosuroides. 

37.  Eurhynchium  myosuroides,  "  female  flower." 

38.  Eurhynchium  pumilum. 

39.  Eurhynchium  Swartzii. 

40.  Fissidens  algarvicus. 

41.  Fissidens  bryoides. 

42.  Fissidens  bryoides,  forma  inconstans. 

43.  Fissidens  Curnowii. 

44.  Fissidens  exilis. 

45.  Fissidens  incurvus,  var.  tamarindifolius. 

47.  Fissidens  rivularis. 

48.  Fissidens  taxifolius. 

49.  Fissidens  viridulus. 

50.  Funaria  fascicularis. 

51.  Funaria  hygrometrica ,  peristome. 

52.  Grimmia  apocarpa. 

53.  Grimmia  apocarpa,  peristome. 

54.  Grimmia  pulvinata. 

55.  Hedwigia  ciliata,  leaves. 

56.  Hylocomium  squarrosum,  peristome. 

57.  Hypnum  cupressi forme,  type. 

58.  Hypnum  cupressiforme,  leaves  of  type. 

59.  Hypnum  cupressiforme,  "  male  flower." 

60.  Hypnum  cupressiforme,  var.  filiforme. 

61.  Hypnum  cupressiforme,  var.  resupinatum. 

62.  Leucobryum  glaucum,  leaves. 

63.  Neckera  pumila. 

64.  Neckera  pumila,  archegonia. 

65.  Orthotrichum  afflne,  leaves  and  "  female  flower." 

66.  Orthotrichum  affine,  to  show  superficial  stomata. 

67.  Orthotrichum  affine,  peristome  (opaque). 


THE    CLUB    CABINET.  649 

DA.  68.  Orthotrichum  diaphanum,  to  show  "immersed"  stomata. 

69.  Orthotrichum  diaphanum,  peristome  (opaque). 

70.  Orthotrichum  Lyellii,  leaves  bearing  gemmae. 

71.  Plagiothecium  elegans,  showing  flagellae. 

72.  Pleuridium  subulatum. 

73.  Polytrichum   formosum,   sections    of    leaves    to    show 

lamellae. 

74.  Pottia  lanceolata. 

75.  Pottia  truncatula. 

76.  Pterygophyllum  lucens. 

77.  Bhacomitrium  lanuginosum. 

78.  Sphagnum  acutifolium,  branches. 

79.  Sphagnum  acutijolium,  to  show  '"  retort  "  cells. 

80.  Sphagnum  cymbifolium,  stem  to  show  spiral  vessels. 

81.  Sphagnum  rigidum,  var.  compaction. 

82.  Tortula  aloides. 

83.  Tortula  laevipila. 

84.  Ulota  phyllantha,  leaves. 

85.  Weber  a  carnea. 

Plant  Structure  (Cellular). 

Presented  by  C.  J.  H.  Sidwell. 

D.B.*  29.  Leaf  of  Holly  Fern. 

30.  Leaf  of  Hymenophyllum  Tunbridgense. 

E.  36.  Leaf  of  Althaea  rosea  :    Hollyhock. 
E.A.  59.  Leaf  of  Pinguicula  vulgaris  :    Bntterwort. 

Seeds. 
Presented  by  C.  J.  H.  Sidwell. 

G.  48.  Orthocarpus  sp. 

49.  Pterospora  andromedea. 
2.  Spergula  minor. 

Fossil  Botany. 
Purchased.     J.  Lomax,  preparer.     3  in.  by  2  in.  slips. 

The  figures  in  (     )  refer  to  illustrations  in  Dr.  D.  H.  Scott's 
Studies  in  Fossil  Botany,  2nd  edition  (copy  in  Q.M.C.  Library;. 


650  THE    CLUB    CABINET. 

Localities  :    all  preparations  from  Shore,  Littleborough,  Lanes., 
unless  otherwise  indicated. 

Y.C.      1.  Tr.  sec.  of  a  large  stem  of  Oalamites. 

2.  (A)  Tr.    sec.   of  stem  of   Calamites,   with   portion    of 

cortex  (figs.  4  and  5)  ;  (B)  portion  of  a  cone  of 
Calamostachys  Binneyana  ;    (C)  a  root  of  Calamites. 

3.  (AA)  Tr.  sees,  of  stems  of  Calamites  ;    (B)  tr.  sec.  of 

small  rootlet,  probably  of  Amyelon  ;  (CC)  tr.  sees. 
of  Amyelon  radicans  (?  the  root  of  one  of  the  Cor- 
daiteae) ;  (D)  leaves  of  Cordaites  ;  (E)  megasporangia 
containing  megaspores. 

4.  (AAA)    Tr.    sees,    of  Astromyelon   (?    the   root  of    a 

Calamites)  ;  (B)  portion  of  a  cone  of  Calamostachys 
Binneyana. 

5.  (A)  Tr.  sec.  of  a  splendid  cone  of  Calamostachys  Bin- 

neyana, with  sporangia  full  of  spores  (fig.  18)  ;  (BB) 
tr.  and  long,  sections  leaves  of  Calamites  (fig.  14)  ; 
(CC)  leaves  of  Sigillariopsis ;  (D)  seed  of  Physo- 
stoma  elegans.  Locality  :  Halifax  Hard  Bed,  Hud- 
dersfield. 

6.  Long.  sec.  cone  of  Calamostachys  Binneyana  (fig.   17). 

Locality  :    Halifax  Hard  Bed,  Huddersfield. 

7.  Tr.  sec.  stem  of  Sphenophyllum  plurifoliatum  (fig.  38). 

8.  Long.  sec.   cone  of  Sphenophyllum  Daivsoni,  showing 

bracts,  etc.,  at  A,  and  sporangia  containing  spores  at 
B  (figs.  42-44). 

9.  Tr.  sec.  stem  of  Lepidodendron  selaginoides.  Locality  : 

Halifax  Hard  Bed,  Huddersfield. 

10.  (A)   Tr.  sec.  stem  of  Lepidodendron  selaginoides  (figs. 

59  and  60) ;  (B)  tr.  sec.  stem  of  Lepidodendron  macro- 
phyllum.  Locality :  Cloughfoot,  Dulesgate,  near 
Todmorden. 

11.  Tr.  sec.  stem  of  Lepidodendron  juliginosum. 

12.  Tr.  sec.  stem  of  Lepidodendron  Harcourtii. 

13.  Tr.  sec.  stem  of  Lepidodendron  Harcourtii,  showing  at 

(A)  the  stele  with  primary  and    secondary  xylem, 

(B)  inner  cortex,  (C)  outer  cortex,  and  (D)  leaf- 
bases  (fig.  56). 

14.  Tang.  sec.  leaf-bases  of  (stem  of  Lepidodendron  Har- 


THE    CLUB    CABINET.  651 

courtii  (Lepidophloios).      In  many  of  the  leaf-bases 
the  vascular  bundle,  parichnos  strands   and   ligule 
are  seen  (fig.  62). 
Y.C.  15.    (A  and  B)  Tr.  sees,  stems  of  Bothrodendron  mundum  ; 
(C)  tr.  sec.  of  a  similar,  but  much  smaller,  stem. 

16.  Tr.   sec.  cone  of  Lepidostrobus  oldhamius  with  micro- 

spores. 

17.  Tr.  sec.  cone  of  Lepidostrobus  oldhamius.      This  cone 

does  not  contain  any  spores,  but  the  axis  and  laminae 
are  well  shown. 

18.  Tr.  sec.  portion  of  Stigmaria  ficoides,  showing  at  A  the 

zone  of  wood,  with    cortex   and  rootlet-bases  at  B 
and  C  (figs.  98  and  100). 

19.  Tang.    sec.    Stigmaria   ficoides    through   outer    cortex, 

cutting  rootlets  transversely  (fig.  97). 

20.  Tang.  sec.  Stigmaria  ficoides  through  zone  of  wood  (fig.  99). 

21.  Radial  sec.  Stigmaria  ficoides. 

22.  Tr.  sec.  Stigmaria  sp.,  showing  zone  of  wood  at  A,  and 

cortex  with  rootlet-bases  at  B. 

23.  Tr.  sec.  stem  of  Etapteris  Laceattei. 

24.  Tr.  sec.  stem  of  Metaclepsydropsis  duplex.     Locality  : 

Pettycur,  Burntisland,  Fife. 

25.  Tr.  sees,  stems  of  Botryopteris  cylindrica,  the  one  at  B 

being  cut  at  junction  with  petiole.     Locality  :    Hali- 
fax Hard  Bed,  Huddersfield. 

26.  Tr.  sec.  stem  of  Zygopteris  bibractensis  (fig.  118). 

27.  Tr.  sees,  stems  and   petioles  of  Stauropteris  oldhamia 

(figs.  126-128). 

28.  Tr.  sec.  stem  of  Lyginodendron  oldhamium  (fig.  129). 

29.  Tang.  sec.  stem  of  Lyginodendron  oldhamium,  rootlets 

being  given  off  at  A  (figs.  138  and  142). 

30.  Radial  sees,  stem  of  Lyginodendron  oldhamium,  rootlets 

being  given  off  at  A  (figs.  138  and  142). 

31.  (A)  Tr.  sec.  young  stem  of  Lyginodendron  ;    (BB)  leaf- 

rachis ;  (C)  root.  Locality :  Dulesgate,  near  Tod- 
morden. 

32.  (A)  Tr.  sec.  leaf-rachis  of  Lyginodendron  oldhamium ; 

(B)  tr.  sec.  young  stem ;  (CC)  tr.  sees,  of  roots 
(figs.  139,  141  and  145).  Locality,  Dulesgate,  near 
Todmorden. 


652  THE    CLUB    CABINET. 

Y.C.  33.  (A)  A  practically  perfect  long.  sec.  seed  of  Physostoma 
elegans,  passing  through  the  micropyle,  and  show- 
ing pollen-chamber   containing  pollen-grains  ;    (BB) 
synangia  of  Telangium  Scottii,   the   microsporangia 
of  Lyginodendron. 

34.  (A)  Tr.  sec.  through  the  centre  of  a  seed  of  Physostoma 

elegans  ;   (B)  tr.  sec.  of  a  Fern  stem. 

35.  Tr.  sees,  steins  of  Heterangium  Grievii  (fig.  154).    Lo- 

cality :    Pettvcur,  Burntisland,  Fife. 

36.  Tr.  sec.  stem  of  Cordaites  (Mesoxylon)  (fig.  189). 

37.  (A)  Tr.  sec.  portion  of  stem  of  Mesoxylon  multirame; 

(B)  root  of  Lyginodendron. 

38.  Tr.  sees.  Amyelon  radicans  (?  the  root  of  one  of  the 

Cordaiteae)  (fig.  191). 

39.  Splendid  tr.  sec.  of  a  leaf  of  Cordaites  (fig.  192). 

40.  Three  sections  of  seeds  of  31  it  ros  per  mum  compression. 


653 


PROCEEDINGS 

OF    THE 

QUEKETT    MICROSCOPICAL  CLUB. 

At  the  506th  Ordinary  Meeting  of  the  Club,  held  on  March  23rd, 
Vice-President  D.  J.  Scourfield,  F.Z.S.,  F.R.M.S.,  in  the  chair, 
the  minutes  of  the  meeting  held  on  February  23rd  were  read  and 
confirmed. 

Messrs.  Joseph  Longmore  and  Joseph  Lovelace  Ribbons  were 
balloted  for  and  duly  elected  members  of  the  Club. 

It  was  announced  that  ninety  slides  had  been  added  to  the 
Cabinet  of  microscopic  objects.  Fourteen  of  these  were  pre- 
sented by  Prof.  E.  A.  Minchin,  in  illustration  of  his  paper  read 
to  the  tlub  recently  on  "  Some  Details  in  the  Anatomy  of  the 
Rat-flea,"  and  were  in  addition  to  those  given  on  that  occasion, 
and  seventy- two  were  presented  by  Mr.  G.  T.  Harris,  illustrating 
his  paper  on  Bryological  Work. 

At  the  request  of  the  Chairman,  Mr.  C.  D.  Soar,  F.L.S., 
F.R.M.S.,  then  read  a  resume  of  a  paper  by  Mr.  Williamson  and 
himself,  on  the  "  British  Hydracarina,  genus  Lebertia."  Mr. 
Soar  said  the  genus  Lebertia  has  been  rather  neglected.  It 
is  certainly  a  difficult  group.  The  species  appeared  to  run 
into  one  another  so  closelv  that  identification  was  rendered 
very  uncertain.  However,  Dr.  Sig  Thor,  of  Norway,  at  last 
took  this  genus  in  hand.  He  divided  it  into  sub-genera, 
and  went  one  by  one  through  every  species  that  had  been  re- 
corded, publishing  altogether  in  the  Zoologischer  Anzeiger  over 
thirty  papers  on  this  genus  alone.  Finding  the  way  thus  pre- 
pared for  us,  Mr.  Williamson  and  myself  have  worked  out  the 
material  which  we  had  been  collecting  together  for  some  years, 
and  the  paper  to-night  is  the  result.  In  the  posthumous  memoir, 
of  Leberts,  published  in  1879,  he  describes  and  figures  a 
Hydracarid,  which  he  considered  new  on  account  of  the  form 
of  the  genital  area.  This  mite  he  named  Pachygaster  tau- 
insignitus.     He  explains  the  specific  name  by  referring  to  the 


654:  PROCEEDINGS    OF   THE 

resemblance  which  the  light  dorsal  marking  bore  to  the  Greek 
letter  tau.  The  generic  name  was  altered  to  Lebertia  (after 
Leberts)  by  Neuman,  in  1880.  Sig  Thor  has  now  divided  the 
genus  into  five  sub-genera.  These  are  as  follows  :  1,  Lebertia; 
2,  Pilolebertia ;  3,  Mixolebertia  ;  4,  Pseudolebertia  ;  5,  Hexa- 
lebertia.  Three  of  the  type  species  have  been  found  in  the 
British  area.  The  type  species  L.  tau-insignitus  at  present  has 
only  been  found  in  the  Lake  of  Geneva.  But,  being  the  type,  we 
have  thought  it  right  to  include  a  description  for  comparison. 
We  have  about  ten  species  for  the  British  area.  One  species, 
Lebertia  trisetica  (Sig  Thor),  sub-genus  Hexalebertia,  was  found 
in  Surrey  in  1896.  It  was  sent  to  Sig  Thor,  who  named  it  in 
1900 ;  two  specimens  were  taken  at  the  time,  but  it  has  never 
been  recorded  since.  Several  of  the  ten  species  have  already 
been  recorded,  but  never  fully  described  in  Britain.  * 

Mr.  J.  W.  Gordon  exhibited  and  described  an  objective  of  the 
same  type  as  that  described  by  Mr.  E.  M.  Nelson  in  the  last 
number  of  the  Journal  of  the  Club,  as  being  the  latest  produc- 
tion of  Messrs.  Zeiss.  Mr.  Gordon  explained  that  his  lens — a 
1/2-in.  dry  lens,  fitted  with  a  front  carrying  an  oil-immersion  lens, 
had  been  constructed  for  him  by  Messrs.  Beck  so  far  back  as 
July  1909,  that  he  has  had  it  in  use  ever  since,  had  shown  it  to 
various  persons,  and  that  the  lens  had  been  described  in  the 
catalogue  of  the  Optical  Convention  of  1912.  The  following  is 
the  description  which  appeared  there  :  '  The  use  of  oil-immer- 
sion has  hitherto  been  confined  to  objectives  of  the  1 /8th- in.  and 
l/12th-in.  class  under  an  impression,  which  proves  to  be  mistaken, 
that  oil-immersion  secures  no  particular  advantages  when 
applied  to  objectives  of  lower  power.  The  model  is  a  1/2- in.  dry 
lens  fitted  with  a  supplementary  lens  of  rather  less  than  hemi- 
spherical angle,  mounted  so  that  the  centre  of  the  sphere  lies 
in  the  object.  The  spherical  surface,  therefore,  produces  no 
refraction,  and  its  addition  to  the  optical  system  involves  no 
change  in  the  correction  of  an  objective  adjusted  for  viewing 
an  uncovered  object.  The  abolition  of  the  top  surface  of  the 
cover-glass,  by  oiling  on  the  supplementary  front  lens  produces 
an  increase  of  50  per  cent,  in  magnifying  power,  and  a  com- 
mensurate increase  in  light-gathering  power.  The  catoptric 
haze  produced  by  internal  reflection  from  the  front  face  of  the 
permanent  front  lens  sinks  into  comparative  insignificance,  and 


QUEKETT    MICROSCOPICAL    CLUB.  655 

a  1/2-in.  dry  lens  is  converted  into  a  l/3rd-in.  immersion  system 
of  much  improved  denning  power." 

Mr.   G.   T.  Harris,   of  Sidmouth,   formerly  a  member  of  the 
Club,  had  presented  to  the  Cabinet  72  micro,  preparations  of 
various  mosses.     He  accompanied  them  with  a  paper  on  "  Micro- 
scopical  Methods   in   Bryological   Work,"    which   was   read   by 
Mr.  F.  J.  Perks.     It  was  pointed  out  that  mosses  did  not  appeal 
very  strongly  to  microseopists  per  se,  as  the  work  to  be  done 
with  them  is  mostly  systematic,  and  they  yield  but  few  "  dis- 
play "    objects.     The    earlier    bryologists     relied    mainly    upon 
herbarium  sheets  for  the  preservation  of  their  specimens  and 
for  identification  purposes — a  plan  sufficient  at  a  time  when  the 
division  of  the  group  into  species,  sub-species  and  varieties  was 
not  carried  out  to  the  extent  it  is  now.     Thirty  years  ago  specific 
distinctions  were  largely  dependent  upon  general  habit  and  the 
presence  or  absence  of  the  so-called  "  nerve  "  and  the  nature  of 
the  leaf  margin.     But  no  bryologist  of  the  present  day  would 
care  to  decide  upon  specific  names  without  microscopic  assist- 
ance.     The  impossibility  of  securing  the  perfect  cleanliness    so 
desirable   in   microscopical   mounts    with   moss    specimens    was 
pointed  out,  the  plants  growing  usually  in  mud,  or  dirty  situa- 
tions, and,  owing  to  their  fragile  constitution,  not  bearing  any 
cleaning  process  without  damage.     Probably  most  bryologists 
relied   on   glycerine   jelly  for   mounting.     Some  years   ago   Mr. 
Harris  prepared  a  considerable  collection  of  Hypnaceae  in  this 
medium,  but  in  about  twelve  months  found  the  whole  of  them 
so  deteriorated  as  to  be  of  no  value.     As  in  other  instances  the 
result  had   been  successful,   he   concluded   the   difficulty  arose 
from  avoidable   causes.     In   his   paper  he  gave  various  precau- 
tions that  should  be  observed  in  using  glycerine  jelly.     Farrant's 
medium  probably  comes  next  to  glycerine  jelly  in  usefulness  ; 
it  is  very  convenient  to  use,  and,  of  course,  allows  of  great  delibera- 
tion  in   arranging  the   object.     For   peristomes,   which  require 
to   be   examined  by  transmitted  light,   it  is   excellent.     Other 
mediums    having    various    advantages    were    then    referred    to, 
particularly  two,   having  copper  acetate  in  their  composition,  . 
one  with  glycerine  and  the  other  with  potassium  acetate ;    for- 
malin was  also  noticed.     Cases  in  which  difficulty  arose  owing 
to  the  dark  colour  and  want  of  transparency  of  the  leaves,  and 
where  manipulation  was  not  easy  owing  to  structure,  were  noted, 


G56  PROCEEDINGS    OF    THE 

and  hints  given  for  overcoming  the  troubles.     The  treatment 
for   satisfactorily   displaying   the    capsule,    with    its    peristome > 
was  entered  upon  at  some  length,  and  a  reference  made  to  the 
section- cutting  required,  in  order  to  render  evident  the  com- 
ponent cells  of  the  stem  and  leaves.     Finally  the  necessity  for  a 
collection  of  slides  as  an  assistance  to  identification  was  insisted 
upon   in   the  following    paragraph :    "  Fifty  years   ago  English 
bryologists  considered  themselves  well  served  with  ten  species 
of  Sphagna,  the  separation  of  which  was  no  great  strain  on  one's 
mental  powers.     At  the  present  time  it  is  useless  to  touch  the 
group  unless  you  are  prepared  to  distinguish  between  at  least 
forty    species,    with    an    average    of    four    varieties    each.     Of 
Sphagnum  acuti  folium  alone,  Warnstorf  describes  sixty  varieties. 
It  will  be  seen  from  this  how  valuable  an  authenticated  collec- 
tion of  slides  would  be  to  the  bewildered  student."     Dixon's 
Student's  Handbook  of  British  Mosses  was  recommended  as   a 
handbook  to  any  one  taking  up  the  study  of  the  group. 

The  paper  was  most  valuable  from  a  practical  point  of  view,, 
and  would  no  doubt  have  led  to  an  interesting  and  useful  dis- 
cussion ;  but,  unfortunately,  owing  to  the  lateness  of  the  hour, 
this  was  altogether  impossible. 

Votes  of  thanks  to  the  donors  of  the  slides  added  to  the 
Cabinet,  and  to  the  authors  of  the  interesting  communications 
brought  before  the  meeting,  were  proposed  from  the  chair,  and 
carried  unanimously,  with  great  heartiness. 


At  the  507th  Ordinary  Meeting  of  the  Club,  held  on  April  27th, 
the  Hon.  Treasurer  (Mr.  F.  J.  Perks)  in  the  chair,  the  minutes  of 
the  meeting  held  on  March  23rd  were  read  and  confirmed. 

Messrs.  William  Williamson,  Roy  Gerald  Evans,  John  Richard 
Duncanson,  Walter  Lauwers  and  the  Rev.  S.  Rennie  Craig 
were  balloted  for  and  duly  elected  members  of  the  Club. 

A  hearty  vote  of  thanks  was  returned  to  Dr.  E.  J.  Spitta  for 
a  presentation  of  lantern  slides  of  historical  interest  to  the  Club, 
which  had  been  previously  exhibited  to  the  members  at  the 
500th  meeting.  The  lantern  slides  in  question  were  placed 
upon  the  table  for  the  inspection  of  the  members.  The  members 
also  thanked  Mr.  C.  Huish  for  presenting  to  the  Club  one  dozen 
slides  of  Mycetozoa.     Amongst  the  additions  to  the  Cabinet  it 


QDEKETT   MICROSCOPICAL   CLUB.  657 

was  mentioned  that  40  slides  illustrative  of  Palaeozoic  Botany 
had  been  purchased. 

Mr.  Ainslie,  R.N.,  then  introduced  the  following  paper,  en- 
titled k"  An  Addition  to  an  Objective "  :  Few  microscopists 
who  have  made  much  use  of  high-power  dry  objectives  have 
failed  to  realise  the  connection  between  the  tube-length  and  the 
thickness  of  the  cover-glass  if  good  definition  is  to  be  obtained. 
This  is,  indeed,  mentioned  in  the  textbooks,  but  not,  as  a  rule, 
at  very  great  length.  Little  is  said,  for  instance,  as  to  the 
amount  of  alteration  required  in  any  given  case.  The  sensitive- 
ness of  objectives  varies  enormously  ;  to  a  certain  extent  with 
the  formula  on  which  the  objective  is  constructed,  but  more 
especially  with  the  power.  As  an  example,  a  1/2-in.  of  high  aper- 
ture, such  as  the  Holos  or  the  Zeiss  Apochromat,  requires 
a  change  of  one  or  two  millimetres  only  in  the  tube-length  to 
compensate  for  a  change  of  0*01  mm.  in  the  thickness  of  the 
cover-glass  ;  for  l/6th,  the  figure  is  from  9  to  13,  while  for  a 
1/8 th,  such  as  the  Leitz  No.  7,  the  figure  is  as  much  as  20  or  21. 
Water-immersions  are  also  subject  to  this  sensitiveness,  though 
to  a  smaller  extent,  the  figure  in  the  case  of  a  Zeiss  "  G  "  being 
9'2.  This  feature  is  more  important  than  is  often  realised,  and 
the  difficulty  caused  thereby  is  enhanced  by  the  extremely  small 
range  of  draw-tube  in  the  average  Continental  stand,  and  un- 
fortunately, in  many  stands  of  English  make.  The  present 
paper  is  an  attempt  to  find  a  way  out  of  the  difficulty,  and  the 
device  suggested  should  be  useful  when  the  range  of  draw-tube  is 
insufficient,  especially  when  the  higher  powers  are  in  use.  Many 
years  ago  the  celebrated  Van  Heurck  used  what  he  called  a 
"transformer"  as  a  means  of  making  a  long- tube  objective 
work  on  a  short  tube,  and  vice  versa.  This  consisted  of  a  con- 
vex or  concave  lens  of  low  power,  fitted  above  the  objective, 
which,  it  will  be  readily  understood,  affords  a  means  of  altering 
the  actual  plane  in  which  the  image  is  formed  (without  affecting 
the  action  of  the  objective),  should  it  happen  that  the  cover- 
glass  is  of  such  thickness  to  require,  for  satisfactory  definition, 
a  tube-length  which  would  bring  the  image  beyond  the  limits 
of  the  draw- tube.  With  the  high-power  dry  objectives  in 
common  use,  such  as  the  average  l/6th,  the  power  of  the  addi- 
tional lens  required  to  effect  the  compensation  for  a  considerable 
change  of  cover- thickness  is  not  excessive ;    a  pair  of  lenses, 

Jourx.  Q.  M.  C,  Series  II. — No.  77.  37 


658  PROCEEDINGS    OF   THE 

convex  and  concave,  of  about  3  diopters  power,  or  about  13  in. 
focus,  will  suffice  to  correct  for  a  very  considerable  range  of 
cover- thickness  ;  but  with  higher  powers,  such  as  a  l/8th,  the 
amount  of  correction  which  can  be  got  in  this  way  is  a  good 
deal  less.  This  might  be  expected,  from  their  greater  sensitive- 
ness to  cover-thickness.  As  an  example  of  what  can  be  done 
with  an  objective  not  too  high  in  power,  it  may  be  said  that  a 
Watson  l/6th,  of  N.A.  0'74,  which  is  normally  corrected  for  a 
cover  0'18  mm.  thick,  and  a  tube-length  of  200  mm.,  can  be 
made  to  work  well  through  a  cover-glass  as  much  as  0"50  mm.  in 
thickness,  if  a  concave  lens  of  —8  diopters  be  placed  behind  it, 
while  with  a  convex  lens  of  the  same  or  somewhat  lower  power 
it  will  work  well  on  an  uncovered  object ;  and  most  other  objec- 
tives of  this  power  will  do  as  well.  I  have  so  far  only  experi- 
mented with  simple  lenses  ;  but  the  chromatic  and  spherical 
corrections  of  the  objective  are  not  perceptibly  affected,  unless 
the  power  of  the  additional  lens  is  as  much  as  10  diopters,  and 
even  then  the  effect  is  not  serious,  and  is  not  appreciable  at  the 
centre  of  the  field.  The  magnifying  power  of  the  objective  is 
somewhat  reduced  by  the  convex  lens,  as  well  as  the  N.A., 
while  with  the  concave  lens  the  effect  is  the  opposite  ;  but  the 
change  is  not  great  if  the  additional  lens  is  placed  as  near  to 
the  back  lens  of  the  objective  as  possible,  though  it  does  very 
well  in  practice  to  place  it  behind  the  objective  mount.  There 
is  yet  another  use  to  which  this  additional  lens  may  be  put, 
which,  so  far  as  I  know,  has  not  been  previously  described.  If 
for  the  oil  in  which  an  oil-immersion  objective  is  immersed  we 
substitute  water,  the  effect  is  just  the  same  in  kind  as  that  of  a 
reduction  in  cover-thickness,  though  greater  in  degree  ;  and  it 
has  been  found  possible  to  convert  an  oil-immersion  into  a 
very  good  water-immersion  by  merely  fitting  behind  it  a  convex 
lens  of  suitable  power.  The  power  of  the  convex  lens  cannot 
be  predicted,  but  must  be  determined  by  trial  for  each  objective. 
It  is  easier  to  effect  the  conversion  in  the  case  of  an  oil-immer- 
sion of  moderate  power,  such  as  l/10th,  than  in  the  case  of  a 
1/1 2th  or  higher  power,  though  a  1/1 2th  can  be  dealt  with  very 
satisfactorily  if  its  working  distance  is  not  too  small.  A  Watson 
tl  Parachromatic  '  l/12th,  for  example,  requires  a  convex  lens 
of  10  diopters.  It  is  important,  in  the  case  of  a  lens  of  this 
power,  to  place  the  additional  lens  as  near  as  possible  to  the 


QUEKETT   MICROSCOPICAL   CLUB.  659 

back  lens  of  the  objective  ;  this  minimises  the  unavoidable  loss 
of  working  distance.  The  additional  lens  may  very  conveniently 
be  fitted  to  the  "  funnel  stop  '  commonly  supplied  with  oil- 
immersions  to  reduce  the  aperture  for  dark-ground  illumination. 
With  an  oil-immersion  thus  converted  to  a  water-immersion,  it 
is  useless  to  expect  that  the  whole  aperture  will  be  available ; 
the  corrections  of  the  objective  are  far  too  much  upset  for  that ; 
but  if  the  additional  lens  is  made  of  such  diameter  as  to 
reduce  the  N.A.  to  about  1*1,  and  if  an  illuminating  cone  not 
exceeding  N.A.  0'75  or  0*8  be  employed,  the  performance  is 
in  all  the  cases  tried  quite  up  to  the  standard  of  the  ordinary 
water-immersion  and  better  than  some.  It  should  not  be 
forgotten  that,  the  substitution  of  water  for  oil  renders  the 
objective  sensitive  to  changes  of  cover-thickness,  and  the  tube- 
length  will  have  to  be  carefully  adjusted  to  compensate  for  this. 
It  is  hoped  that  this  method  of  converting  an  oil-immersion 
into  a  water-immersion  may  be  found  of  use,  especially  to 
those  who  occasionally  require  to  use  a  water-immersion  for 
work  on  living  specimens,  or  in  other  work  for  which  an  oil- 
immersion  would  be  inconvenient. 

Objects  were  exhibited  under  microscopes  kindly  lent  by 
Messrs.  H.  F.  Angus  &  Co.,  and  by  Messrs.  W.  Watson  & 
Son,  to  illustrate  the  paper  ;    these  were  : 

1.  A  specimen  of  polished  steel,  with  a  Watson  4  mm.  apo- 
chromatic,  N.A.  0'85,  a  convex  lens  of  6  diopters  being  used 
to  correct  for  the  absence  of  a  cover-glass.  (Magnifying  power, 
340  diameters.) 

2.  Bacillus  typhosus,  showing  flagella,  with  a  Watson  l/6th, 
N.A.  0'74,  an  extra  cover  being  introduced  to  bring  the  total 
thickness  up  to  0'50  mm.  and  a  concave  lens  of  —8  diopters  being 
introduced.     (510  diameters.) 

3.  Tubercle  bacillus,  with  a  Watson  l/12th  oil-immersion, 
N.A.  1*3  working  with  a  water-immersion,  a  convex  lens  of 
-j-10  diopters  being  introduced  to  effect  the  conversion.  (940 
diameters.) 

The  Hon.  Secretary  (Mr.  F.  Burton)  then  read  ';  Notes  on  a 
Diatom  Structure;'  by  Mr.  A.  A.  C.  Eliot  Merlin,  F.R.M.S. 
The  author  drew  attention  to  a  very  beautiful  form  of  tertiary 
structure  he  recently  found  on  a  variety  of  Aulacodiscus  comberi 
from  Oarnaru.     The  valve  is  on  a  styrax  type  slide  of  230  forms 


660  PROCEEDINGS    OF   THE 

from  that  locality,  and  is  covered  with  a  network  of  dark,  well- 
defined  secondaries,  except  on  the  parts  occupied  by  the  large 
primaries.  Each  of  the  dark  secondaries  splits  up  into  three  or 
four  parts  by  a  bright  cross-bar  arrangement.  This  structure 
requires  a  good  oil-immersion  objective  and  a  very  considerable 
magnification  to  render  it  readily  discernible. 

A  photograph  of  the  above  was  exhibited,  and  Mr.  E.  M. 
Nelson,  F.R.M.S.,  confirmed  the  presence  of  this  structure  from 
a  specimen  in  his  cabinet.  Mr.  Merlin  also  exhibited  two  other 
photographs  of  a  diatom.  Mr.  Nelson  had  written  him  that  he 
had  discovered  that  Coscinodiscus  simbirsJiii,  which,  with  ordinary 
transmitted  light,  resembles  Coscinodiscus  asteromphalus ,  when 
examined  with  a  dark  ground  and  a  rather  small  stop  looks  like 
Actinoptychus  splendens.  This  led  him  to  search  for  the  diatom 
specified,  and  although  this  could  not  be  found,  he  found  one 
which,  with  a  dark-ground  illumination,  revealed  a  beautiful 
radiating  structure,  somewhat  resembling  a  Heliopelta,  which 
was  not  observable  by  transmitted  light.  On  the  photographs 
of  this  specimen  being  examined  it  was  identified  by  Mr.  Mor- 
land  as  Janischia  antiqua,  Grunow.  Mr.  Merlin  further  pointed 
out  that,  although  diatom-dotting  has  influenced  the  develop- 
ment of  the  microscope  towards  perfection  more  than  anything 
else,  he  is  unable  to  find  out  particulars  of  its  introduction.  Mr. 
Nelson  sent  an  extract  from  Messrs.  Sollitt  and  Harrison's 
paper,  read  before  the  British  Association  at  Hull  in  1853  : 
"  We  in  Hull  first  discovered  the  delicate  markings  on  their 
silicious  coverings,  and  pointed  them  out  to  others  as  the  proper 
tests  for  lenses.  The  first  of  the  Diatomaceae  on  which  the 
lines  were  seen  was  the  Navicula  hippocampus  of  Ehrenberg — 
this  was  early  in  1841,  when  specimens  were  sent  to  the 
Microscopical  Society  of  London — also  to  Mr.  Smith,  Mr. 
Ross,  Messrs.  Powell  &  Lealand,  M.  Nachet  in  Paris,  and  Pro- 
fessor Baile}7  in  America,  all  of  whom  at  once  saw  the  excellency 
of  these  objects  as  tests  for  the  microscope." 


At  the  508th  Ordinary  Meeting  of  the  Club,  held  on  Tuesday, 
May  25th,  the  Vice-President,  Mr.  D.  J.  Scourfield,  F.Z.S., 
F.R.M.S.,  in  the  chair,  the  minutes  of  the  meeting  held  on 
April  27th  were  read  and  confirmed. 


QUEKETT    MICROSCOPICAL   CLUE.  (361 

Messrs.  Sydney  Harold  Robinson,  Walter  E.  T.  Hartley  and 
John  F.  Donald  Tutt  were  balloted  for  and  duly  elected  mem- 
bers of  the  Club. 

The  Hon.  Secretary  announced  the  presentation  to  the  Club's 
Cabinet  of  a  further  five  slides  of  rare  mosses  by  Mr.  G.  T.  Harris. 
Also  an  addition  to  the  Club's  album  of  a  photograph  of  Mr. 
G.  C.  Karop,  who  was  Secretary  of  the  Club  from  1883  until 
February  1904. 

Mr.  Seabury  Edwardes,  F.R.M.S.,  contributed  a  paper  giving 
some  practical  details  on  mounting  diatoms  in  phosphorus.  The 
paper  was  read  in  abstract  by  the  Hon.  Secretary,  but  whether 
any  member  has  the  temerity  to  put  Mr.  Edwardes'  directions  to 
a  practical  test  seems  very  doubtful.  The  results  even  on  the 
author's  showing  are  somewhat  problematical,  and  the  process 
very  dangerous.  It  is  hardly  likely  to  come  into  use,  as  there 
are  simpler  methods  of  mounting  diatoms  in  high  refractive 
media. 

Further  notes  on  the  cultivation  of  plasmodia  of  Badhamia 
utricular  is  were  given  by  Mr.  A.  E.  Hilton.  A  year  ago  he 
called  attention  to  a  method  of  cultivating  this  plasmodium  on 
bread,  with  occasional  applications  of  a  solution  of  ammonium 
phosphate  and  cane-sugar.  In  the  discussion  following,  two 
points  were  raised  which  he  was  unable  to  answer.  One  was 
whether  this  particular  species  of  Mycetozoa  could  be  obtained 
by  the  cultivation  of  spores  ;  the  other,  whether  it  would,  when 
artificially  fed,  form  sporangia.  As  a  result  of  further  investiga- 
tion, Mr.  Hilton  stated  that  it  is  possible  to  cultivate  the  spores, 
but  not  always  easy.  With  regard  to  the  second  question, 
whether  it  would  form  sporangia  when  artificially  fed,  he  was 
now  able  to  state  that  it  would,  but  with  certain  reservations. 
On  February  19th  last  a  plasmodium  of  B.  utricularis  was  started 
by  reviving  a  fragment  of  sclerotium,  which  was  treated  entirely 
with  bread  and  water  and  the  chemical  solution,  adding,  how- 
ever, calcium  phosphate,  with  a  view  to  supplying  the  lime 
usually  found  in  this  form  of  sporangium.  The  cold  weather 
made  growth  slow  ;  but  on  May  5th  the  plasmodium  changed 
into  a  quantity  of  sporangia.  There  are  striking  differences 
between  these  and  those  produced  under  natural  conditions. 
The  shape  is  similar  ;  but  instead  of  the  usual  cinereous  hue, 
they   are   a   dull   purple-black,    cinnamon-brown,    or   even   pale 


662  PROCEEDINGS    OF   THE 

biscuit  tint.  All  are  sprinkled  with  white  crystalline  particles.  ' 
The  sporangium  walls,  usually  very  thin  and  fragile,  are  hard, 
thick  and  chippy,  and  there  is  no  distinguishable  capillitium. 
They  are  also  only  about  half  the  ordinary  diameter.  The 
spores  themselves,  generally  bright  brown  and  spinulose,  are 
smooth  and  almost  colourless,  but  quite  the  usual  size,  if  not 
slightly  larger,  and  in  other  respects  appear  perfectly  normal. 
Mr.  Hilton  had  not  yet  attempted  to  cultivate  these  spores. 

The  Hon.  Secretary  then  read  a  paper  on  Hydrodictyon  reti- 
culatum,  or  utriculatum.  Last  September  he  found  an  immense 
quantity  of  this  alga  in  the  lake  in  Kew  Gardens.  According 
to  Dr.  Cooke  the  "  water-net  "  is  one  of  the  earliest  enumerated 
freshwater  algae  in  Britain.  It  is  figured  in  PlukeneFs  Alma 
Geslum  in  1691,  and  was  again  mentioned  by  Bobart  in  1699. 
Ray  includes  it  in  his  "  Synopsis  "  in  1724  as  Conferva  reticulata, 
and  says  that  it  was  found  in  ditches  about  Westminster  and 
Hounslow.  Owing  to  various  characteristics  which  are  not 
found  in  other  algae,  Hydrodictyon  has  been  placed  in  a  sub- 
family by  itself.  It  consists  of  a  saccate  net-like  object  varying 
in  size  from  almost  microscopic  up  to  a  length  of  several  inches. 
The  cells  also  vary  in  size  when  young  from  8  /j.  to  10  /x  in  diameter 
and  grow  sometimes  to  a  length  of  1  cm. — say,  2/5th-in.  They 
are  approximately  cylindrical  in  shape,  and  are  arranged  with 
their  ends  in  contact,  usually  three  meeting  at  such  an  angle 
as  to  form  the  typical  hexagonal  meshes.  They  have  a  some- 
what thick  wall,  and  inside  a  layer  of  protoplasm,  in  which  the  . 
green  chlorophyll  is  diffused,  not  collected  into  definite  chloro- 
plasts  as  usual  in  algae.  The  centre  is  filled  with  cell  sap.  The 
protoplasm  contains  numerous  and  quite  typical  pyrenoids 
each  consisting  of  a  central  body  with  a  layer  of  starch-grains 
outside.  These  may  be  considered  as  food  reserve.  At  the 
commencement  of  reproduction  they  disappear,  and  are  obviously 
used  up.  There  is  also  fine-grained  starch  in  the  protoplasm, 
used  for  the  purposes  of  life  and  growth.  Many  nuclei  are  pre- 
sent in  each  cell.  The  net  is  born  with  a  certain  number  of 
cells,  and  always  continues  the  same  ;  if,  owing  to  injury,  a  part 
is  destroyed,  it  is  not  replaced.  A  small,  complete  net,  con- 
sisting, it  may  be,  of  some  thousands  of  cells,  is  formed  inside 
each  of  the  members  of  the  original  net.  The  mother  cell-wall 
gelatinises,  and  the  young  one  is  set  free.     What  causes  the  ap- 


QUEKETT    MICROSCOPICAL   CLUB.  663 

pearancc  or  disappearance  of  Hydrodictyon  is  not  understood. 
After  being  very  plentiful  it  will  totally  disappear  perhaps  for 
several  years,  and  then  there  is  a  sudden  reappearance.  These 
outbreaks  are  known  in  some  parts  as  the  "  breaking  of  the 
meres."  For  instance.  Hydrodictyon  appeared  formerly  in 
the  lake  in  Kew  Gardens.  Mr.  Burton  has  looked  for  it  for 
more  than  thirty  years  there,  and  only  found  one  very  small 
specimen  up  to  last  autumn,  when  a  tremendous  outbreak 
occurred.  In  less  than  four  weeks,  however,  it  had  all  disap- 
peared. He  suggested  that  the  probable  explanation  was  a 
combination  of  several  favourable  circumstances  which  do  not 
frequently  arise,  possibly  some  special  type  of  weather  and 
some  narrow  range  of  temperature  at  a  particular  season. 

Mr.  F.  J.  Perks  (Hon.  Treasurer)  read  some  Notes  by  Mr. 
E.  M.  Nelson  on  various  insect  structures.  The  wing  of  the 
Neuropteron,  Agrion  pulchdlum,  he  pointed  out,  is  a  very 
interesting  microscopical  object.  The  membrane  is  double, 
bordered  by  a  rim  edged  with  saw-like  teeth,  the  surface  is 
divided  by  nervures  which  are  peculiar — the  transverse  bars,  as 
well  as  four  longitudinal,  have  on  one  edge  thorns,  and  on  the 
other  saw-like  teeth  ;  three  other  longitudinal  ribs  have  saw- 
teeth on  one  edge  and  fine  teeth  on  the  other,  but  no  thorns.  At 
one  part  on  the  edge  of  the  wing  is  a  dark-coloured  compartment 
improperly  called  Ci  stigma."  This  is  really  a  pocket,  and  is 
obviously  used  for  producing  a  sound.  If  the  border  of  the 
wing  is  examined  through  a  half-inch  objective  and  a  x  10  eyepiece, 
a  delicate  hair  can  be  seen  between  the  teeth  of  the  saw,  very 
minute,  the  largest  found  measuring  23  /x  in  length  and  2  /x  in 
breadth.  They  spring  out  of  circular  rings,  as  do  most  insect 
hairs,  but  not  like  those  on  the  membrane  of  a  blowfly's  tongue, 
which  have  no  rings.  Mr.  Nelson  points  out  that  careful  ex- 
amination of  the  small  hairs  on  the  wing  of  a  wasp  will  show 
they  are  twisted  like  the  tusk  of  a  narwhal.  The  hairs  on  a 
bee's  wing  are  similar,  but  not  so  twisted,  while  they  have  no 
ring.  Those  on  the  wing  of  a  saw-fly  issue  from  a  boss.  The 
hairs  on  the  ovipositor  of  Phalangia  have  a  ringed  base,  and' 
on  the  last  two  terminal  stripes,  where  the  hairs  are  larger,  the 
ringed  boss  has  a  circle  of  minute  hairs.  The  hair  itse  f  is 
tubular,  has  a  filamentous  end,  and  at  the  side  there  is  a  minute 
prong.     At  the  end  of  each  of  the  two  lobes  of  the  ovipositor 


664  PROCEEDINGS    OF   THE 

is  a  small  boss  covered  with  minute  hairs,  without  ring  bases/ 
and  bluntened,  probably  open  ;  they  have  internal  ring  (not 
spiral)  structure  similar  to  an  artery.  The  examination  of  the 
mandibles  of  a  gadfly,  Tabanus  bovinus,  will  show  the  most 
wonderful  saw  in  the  world,  having  10,000  to  16,000  teeth  per 
inch  on  one  edge,  while  the  other  is  the  keenest  blade  in  exist- 
ence. After  describing  the  sting  of  a  hornet,  Vespa  crabro, 
he  draws  attention  to  the  pygidium  of  a  flea.  If  the  right-  and 
left-hand  edges  are  examined,  a  Eustachian  tube  will  be  seen. 
The  apparatus  corresponds  to  the  drum  of  an  ear,  and  must 
have  an  air-passage  to  equalise  the  pressure  on  either  side.  At 
the  base  of  the  haltere  in  a  blowfly  a  similar  tube  is  easily  seen. 


At  the  509th  Ordinary  Meeting  of  the  Club,  held  on  June  22nd, 
1915,  the  President,  Professor  Arthur  Dendy,  D.Sc,  F.R.S..  in 
the  chair,  the  minutes  of  the  meeting  held  on  May  28th  were 
read  and  confirmed. 

Mr.  Reginald  Arthur  Price  was  balloted  for  and  duly  elected 
a  member  of  the  Club. 

The  President  stated  that,  as  the  first  meeting  to  consider 
the  formation  of  the  Club  was  held  on  June  14th,  1865,  the 
present  meeting  marked  an  epoch  in  the  history  of  the  Quekett 
Club,  as  it  concluded  the  first  fifty  years  of  work,  and  all  who 
knew  would  agree  that  it  had  been  to  them  a  half-century  full 
of  important  results,  and  that  the  present  condition  of  the  Club 
was  very  satisfactory.  Most  of  the  members  present  knew  that 
the  Committee  had  begun  to  arrange  for  the  celebration  of  this 
event,  but  they  had  since  thought  it  necessary  to  abandon  the 
idea,  as  it  was  felt  that  any  kind  of  rejoicing  would  be  out  of 
harmony  with  the  prevailing  feeling  at  the  present  time,  and 
he  thought  they  would  all  be  agreed  that  the  most  dignified 
thing  they  could  do  under  the  circumstances  was  to  defer  that 
celebration.  He  wished  also  in  the  first  place  to  say  that  the 
Hon.  Editor  had  inserted  in  the  last  number  of  the  Journal  a 
very  interesting  account  of  the  early  history  of  the  Club,  which 
would  no  doubt  be  read  with  great  pleasure  by  the  members. 
Another  point  was  that  they  had  the  pleasure  of  seeing  that 
evening  present  at  their  meeting  three  of  the  original  members 
of  the  Club— Mr.  R.  T.  Lewis,  who  had  acted  as  their  Honorary 


QUEKETT    MICROSCOPICAL    CLUB.  663 

Reporter  from  its  commencement,  Mr.  Alpkeus  Smith,  who  was 
their  Honorary  Librarian  for  forty  years,  and  Mr.  Thomas 
Powell,  whom  they  all  had  the  pleasure  recently  of  congratulating 
upon  the  attainment  of  his  eightieth  birthady.  He  hoped  they 
would  long  be  able  to  attend  the  meetings  of  the  Club. 

Dr.  John  W.  Evans,  of  the  Geological  Department  of  the 
Imperial  College  of  Science,  South  Kensington,  then  gave  a 
lecture  on  ';  The  Microscopical  Examination  of  Minerals." 

Dr.  Evans  stated  that  for  many  reasons  a  stationary  stage 
and  revolving  nicols  are  most  convenient,  but  add  greatly  to 
expense,  and  he  found  high-power  objectives  of  great  use  for 
special  examinations.  Tube  and  eyepiece  must  be  provided 
with  a  slot,  so  that  a  quartz  wedge,  gypsum  plate,  or  eyepiece 
micrometer  may  be  inserted  in  the  focus  of  the  eyepiece.  This 
slot  should  be  placed  in  a  diagonal  position,  and  not,  like  in 
many  foreign  instruments,  from  left  to  right,  which  makes 
special  wedges  and  plates  necessary.  A  good  rock  slice  should 
range  between  20  and  30  microns  in  thickness,  but  with  trans- 
parent minerals  much  thicker  sections  may  be  usefully  em- 
ployed. For  examination  the  section  should  be  brought  into 
the  centre  of  the  field,  so  that  it  lies  beneath  the  intersection 
of  the  crossed  wires,  and  the  stage  rotated  until  the  index  read- 
ing is  zero.  If  with  both  nicols  in  the  crossed  position  and 
the  stage  rotated  the  crystal  section  remain  dark  through  a 
complete  rotation,  it  is  either  isotropic  or  cut  at  right  angles 
to  the  optic  axis  of  a  uniaxial  crystal.  If  it  continue  uniformly 
faintly  illuminated,  it  is  at  right  angles  to  an  optic  axis  of  a 
biaxial  crystal.  Usually  it  will  be  dark  at  four  points  in  the 
rotation  when  the  directions  of  vibration  of  light  traversing 
the  crystal  section  are  parallel  to  those  of  the  nicols.  These 
four  points  are  known  as  "  extinctions.'' 

There  is  usually  some  difficulty  in  determining  the  position 
of  maximum  darkness  corresponding  to  the  true  position  of 
extinction,  and  one  of  the  simplest  of  many  methods  is  to  rotate 
the  stage  towards  the  position  of  extinction  alternately  from 
opposite  directions  and  to  note  the  readings  on  each  side  where 
the  same  degree  of  obscuration  has  been  obtained.  The  mean 
of  several  pairs  of  observations  will  give  approximately  the 
true  position. 

Ascertain  which  of  the  extinctions  or  directions  of  vibration 


666  PROCEEDINGS    OF   THE 

in  the  crystal  section  is  the  direction  of  vibration  of  light  with  ' 
the  greater  velocity,  and  which  that  of  light  with  the  less  velocity, 
and  determine,  at  the  same  time,  the  relative  retardation,  or,  in 
other  words,  how  far  the  slower  moving  vibrations  have  lagged 
behind  the  faster.  (This  is  usually  measured  in  micro-milli- 
metres, or  millionths  of  a  millimetre.)  For  the  purpose  of 
making  these  determinations  we  insert  both  nicols  in  the  cross 
position  and  rotate  the  stage  till  the  direction  of  vibration  is 
diagonal  to  those  of  the  nicols.  The  two  vibrations  which  pass 
the  lower  nicol  are  now  resolved  along  the  two  directions  of 
vibration  of  the  section.  If  there  were  no  relative  retardation 
they  would  in  emergence  recombine  to  form  a  vibration  parallel 
to  the  same  direction  as  before,  and  would  be  extinguished  by 
the  upper  nicol.  As  a  result  of  the  relative  retardation,  however, 
the  various  colours  of  the  spectrum  are  transmitted  in  different 
degrees,  so  that  the  compound  tints  known  as  interference 
colours  are  obtained.  These  are  dependent  upon  the  amount 
of  it,  which  is  usually  about  the  same  for  all  colours  of  the 
spectrum. 

Interference  colours  commence  with  complete  darkness  at 
zero  relative  retardation  and  pass  through  grey,  white,  yellow, 
orange  and  red,  which  last  is  seen  when  the  relative  retardation 
reaches  550  micro-m.m.  These  constitute  the  colours  of  the  first 
order.  Then  followr  purple,  violet,  blue,  green,  yellow  and  red 
up  to  a  relative  retardation  of  1,000.  These  are  the  second 
order.  Every  addition  of  550  micro-m.m.  corresponds  to  another 
order  with  a  similar  succession  of  colours,  gradually  becoming 
more  complex  until  they  are  delicate  shades  of  green  and  pink, 
and  with  a  relative  retardation  of  about  4,000  micro-m.m.  they 
slowly  pass  into  white  light. 

If  one  nicol  be  rotated  through  a  quarter  turn  so  that  the 
directions  of  vibrations  of  the  two  nicols  are  parallel,  the  colours 
are  seen  to  pass  through  brown,  red  and  blue  to  the  yellowish 
green,  marking  the  end  of  the  first  order  at  550.  Then  the 
second,  and  gradually  the  colours  fade  into  white  light,  exactly 
as  with  crossed  nicols. 

The  amount  of  relative  retardation  in  a  crystal  section  may 
be  roughly  estimated  directly  from  the  interference  colours 
between  crossed  and  parallel  nicols  by  comparison  with  tables 
or    lithographic    plates    of    colours    giving    the    corresponding 


QUEKETT    MICROSCOPICAL   CLUB.  667 

relative  retardations  (one  was  exhibited  at  the  lecture),  but  in 
determining  colours  so  much  depends  upon  the  idiosyncrasy 
of  the  observer,  and  the  character  of  the  light,  that  results 
can  only  be  relied  on  within  very  wide  limits.  In  the  smoky 
atmosphere  of  a  London  winter,  for  instance,  the  blue  of  the 
second  order  appears  to  pass  into  greenish  yellow  without  any 
definite  green  intervening.  Relative  retardation  is  equal  to  the 
product  of  the  thickness  of  the  section  and  the  birefringence, 
which  is  the  relative  retardation  in  a  unit  of  distance,  and  is 
equal  to  the  difference  between  the  refractive  indices  of  the 
two  directions  of  vibration.  In  the  case  of  a  section  of  quartz 
21  microns  thick,  cut  parallel  to  the  optic  axis,  the  indices  of 
refraction  are  1*544  and  1*553,  and  the  bi-refringence  therefore 
0*009.  Accordingly  the  relative  retardation  =  21  x  0*009  =  0*189 
of  a  micron.  For  the  purposes  of  determining  the  character  of 
extinctions  and  the  amount  of  relative  retardation  a  quartz 
wedge  or  mica  ladder  may  be  employed. 

Dr.  F.  E.  Wright,  of  the  Smithsonian  Institute,  Philadelphia, 
devised  a  combination  of  quartz  wedge  and  gypsum,  and  Dr. 
Evans  has  successfully  employed  the  same  idea. 

A  quartz  wedge  is  superposed  on  a  gypsum  plate,  both  being 
constructed  with  the  usual  orientation,  so  as  to  leave  beyond 
the*  thin  end  of  the  wedge  a  square  of  gypsum,  which  may  be 
used  as  an  ordinary  gypsum  plate.  The  quartz  will  show  a 
black  band  where  it  neutralises  the  gypsum.  The  point  is 
marked  zero.  Every  hundred  micro-m.m.  of  relative  retarda- 
tion is  shown  either  way.  If  the  direction  of  the  crystal  section 
parallel  to  the  slot  be  fast,  the  band  wrill  move  towards  the  thick 
end  of  the  wedge  ;    if  slow,  towards  the  thin  end. 

The  mica  ladder  consists  of  a  succession  of  narrow  cleavage 
plates  of  muscovite,  with  their  length  cut  parallel  to  the  trace 
of  the  optic  axial  plane,  and  therefore  slow.  Each  strip  should 
have  a  relative  retardation  of  100  micro-m.m.  They  are  of 
different  lengths  and  superposed  to  form  a  succession  of  steps 
each  large  enough  to  cover  the  whole  cone  of  light  in  the  lower 
slot,  where  they  are  usually  employed,  though  useful  in  the 
focus  of  the  eyepiece,  if  the  upper  nicol  be  placed  above  them. 
In  either  case  they  show  a  discontinuous  series  of  colours  corre- 
sponding to  differences  of  100  micro-m.m.  If  inserted  over  a 
section  it  is  easy  to  show  whether  the  two  show  additive  or 


668      PROCEEDINGS    OF    THE    QUEKETT    MICROSCOPICAL    CLUB. 

subtractive  relations.  In  the  former  case  the  stage  should  be 
rotated  till  the  fast  direction  of  the  section  is  parallel  to  the  slot. 
It  may  happen,  then,  that  the  section  is  neutralised  by  one  of 
the  steps,  and  therefore  is  of  the  same  relative  retardation.  If 
one  step  just  fails  to  neutralise  and  the  next  higher  will  more 
than  do  so,  and  neither  are  completely  dark,  then  if  they  be 
equally  bright,  the  relative  retardation  must  be  midway  between  ; 
if  one  is  darker,  then  it  will  be  proportionately  nearer  to  that 
step.  In  this  way  the  relative  retardation  can  be  estimated  to 
within  20  or  30  micro-m.m.  When  the  directions-image — i.e. 
the  object  viewed  without  an  eyepiece  reflected  on  the  back 
lens  of  the  objective — is  examined  between  crossed  nicols,  it 
shows  in  the  centre  of  the  field  the  same  interference  colours  as 
that  seen  in  the  object  image.  The  colours  move  with  the  stage 
as  it  rotates  without  suffering  any  changes  of  configuration, 
x^t  the  same  time  the  field  is  traversed  by  dark  bands  or 
brushes,  which  constitute  the  isogyre.  As  the  rotation  proceeds, 
these  change  both  their  position  and  their  shape  and  may  from 
time  to  time  leave  the  field  altogether.  When  the  stage  is  in 
the  position  corresponding  to  extinction  in  the  object-image  or, 
in  other  words,  when  the  vibrations  in  the  section  are  parallel 
to  the  cross  wires,  the  isogyre  passes  through  the  centre  of  the 
field  and  is  known  as  a  ':  central  isogyre." 

Dr.  Evans  concluded  his  lecture  by  describing  the  technical 
indications  of  the  different  isogyres. 

The  lecture  was  fully  illustrated  by  diagrams  and  coloured 
lantern  slides,  which  were,  Dr.  Evans  pointed  out,  mostly  due 
to  the  art  of  Mr.  C.  H.  Caffyn. 

There  was  a  collection  of  photographs  of  rock  sections  on 
Lumiere  Autochrome  plates,  exhibited  by  Messrs.  J.  W.  Ogilvv 
and  C.  H.  Caffyn,  and  also  a  series  of  exhibits  showing  the  pro- 
cess of  mounting  a  rock  section. 


669 


OBITUARY    NOTICE. 
EDWARD   ALFRED    MINCHIN,    M.A.,    F.R.S. 

{Born  February  2V>th,   I860;    died  September  30th,  1915.) 

The  members  of  the  Quekett  Microscopical  Club  will  have  heard 
with  the  deepest  regret  the  sad  news  of  the  death  of  our  former 
President,  Professor  E.  A.  Minchin,  MA.,  F.R.S. ,  which  took 
place  on  September  30th  at  Selsey,  at  the  comparatively  early 
age  of  forty-nine. 

Professor  Minchin  was  one  of  the  most  distinguished  men  of 
science  who  have  ever  occupied  the  presidential  chair  of  this 
Club,  and  his  stimulating  addresses  will  long  be  remembered  by 
those  of  us  who  were  privileged  to  hear  them,  while  the  kindly 
courtesy  with  which  he  was  always  ready  to  share  his  unrivalled 
knowledge  of  his  special  subjects  endeared  him  to  all  his  fellow - 
workers.  It  is  to  Professor  Minchin  that  I  owe  my  own  intro- 
duction to  the  Club,  and  it  may  interest  my  fellow-members  to 
hear  of  the  cordial  appreciation  with  which  he  spoke  to  me  of  the 
Club  and  its  work.  It  was  quite  evident  that  he  derived  a  very 
real  satisfaction  from  his  association  with  its  members. 

The  Quekett  Club,  however,  formed  but  a  small  part  of  the 
field  in  which  Professor  Minchin  exercised  his  scientific  activities. 
Both  as  a  teacher  and  as  an  original  investigator  of  the  first  rank, 
he  was  well  known  to  zoologists  in  all  parts  of  the  civilised  world. 
His  luminous  general  treatises,  especially  those  on  the  Sponges 
and  the  Protozoa,  are  landmarks  in  the  progress  of  zoological 
science,  while  at  the  same  time  his  own  researches  have  broken 
new  ground  in  many  directions. 

He  was,  I  think,  the  most  conscientious  investigator  that  I 
have  ever  had  the  good  fortune  to  meet.  In  the  study  of  Spong- 
ology  in  particular  he  introduced  a  standard  of  painstaking 
accuracy  that  was  sorely  needed,  and  set  an  example  of  thorough- 
ness that  will  be  hard  indeed  for  those  who  follow  him  to  emulate. 
His  most  striking  and  important  contributions  to  this  depart- 
ment of  zoology  are  his  beautiful  researches  on  the   histology 


670  OBITUARY    NOTICE. 

and  embryology  of  the  Calcarea,  especially  those  dealing  with 
the  origin  and  development  of  the  triradiate  spicules,  or,  rather, 
spicule-systeins,  as  he  showed  them  to  be.  The  conclusions  at 
which  he  arrived  as  the  result  of  these  investigations  were  of  a 
startling  and  wholly  unexpected  nature.  His  most  important 
memoirs  on  Sponges  were  produced  while  he  occupied  the  chair 
of  Zoology  at  University  College,  London,  and  it  was,  I  know,  no 
small  grief  to  him  to  have  to  abandon  these  researches,  at 
any  rate  to  a  large  extent,  when  he  accepted  the  newly  created 
chair  of  Protozoology  in  the  University  of  London  and  trans- 
ferred his  headquarters  to  the  Lister  Institute  of  Preventive 
Medicine  at  Chelsea. 

While  at  University  College  he  had  already  won  a  great  reputa- 
tion as  a  student  of  the  Sporozoa,  a  group  of  Protozoa  which  in 
recent  years  has  assumed  such  immense  imj>ortance  from  the 
medical  standpoint,  and  at  the  Lister  Institute  the  parasitic 
Protozoa  necessarily  claimed  his  chief  attention.  Here  his  wonder- 
ful  mastery  of  microscopical  technique  stood  him  in  good  stead, 
and  his  exquisitely  illustrated  memoirs  on  the  Trypanosomes, 
published  in  The  Quarterly  Journal  of  Microscopical  Science, 
would  alone  form  a  lasting  monument  to  his  industry  and  skill. 
His  work  in  this  direction  took  him  far  afield,  for  even  before  he 
resigned  his  chair  at  University  College  he  had  visited  Uganda 
as  a  member  of  the  Royal  Society's  Commission  on  Sleeping 
Sickness.  His  Introduction  to  the  Study  of  the  Protozoa,  with 
special  reference  to  the  parasitic  forms,  published  in  1912,  will  long 
remain  the  standard  treatise  on  this  most  important  subject. 

The  amount  of  hard  work  that  Minchin  managed  to  get  through 
is  marvellous.  In  spite  of  his  delicate  health  and  his  preoccupa- 
tion with  original  research  of  the  most  intricate  and  difficult 
character,  and  in  addition  to  his  numerous  duties  as  a  teaching 
professor,  he  managed  to  find  time  to  take  an  active  part  in  the 
work  of  scientific  societies.  His  zeal  and  energy  as  President  of 
the  Quekett  Microscopical  Club  are  fresh  in  the  memories  of  all 
of  us,  but  he  was  also  a  Vice-President  of  the  Zoological  Society 
and  latterly  Zoological  Secretary  of  the  Linnean  Society. 

Minchin' s  last  contribution  to  science  was  his  Presidential 
Address  to  the  Zoological  Section  of  the  British  Association  at 
Manchester,  in  September  last.  Those  of  us  who  were  present 
on  that  occasion  knew  that  the  end  was  not  far  off,  and  it  was  with 


OBITUARY    NOTICE.  671 

sad  feelings  that  we  listened  to  his  friend  Mr.  Heron- Allen,  whom 
Minchin  had  chosen  to  read  the  address  on  his  behalf.  -In  this 
address  the  departing  master  summed  up  his  views  on  that 
fascinating  subject,  the  evolution  of  the  cell,  and  showed  us, 
what  indeed  we  all  knew  before,  that  he  was  not  only  a  specialist 
of  the  highest  type,  but  gifted  with  a  deep  insight  into  the  funda- 
mental problems  of  his  beloved  science. 

A.  D. 


673 


INDEX. 


A 

I 'AGE 

Abbe,  Prof.      On  the  Aperto- 

meter  .  .  .288 

Acercus  longiiarsus  sp.  nov.      140 

Actinocyclus       .  .  .28 

Aclinocyclus   Ralfsii  and   a 

Coloured  Coma.     E.  M. 

Nelson         .  .  .      100 

Actinoptychus   .  .  .36 

Ayr  ion  pulchellum       .  .      593 

Ainslie,  M.  A.    A  variation  of 

Cheshire's  Apertometer     287 

—  An  addition  to  the  objec- 

tive   ....      561 
Akehurst,  S.  C.     A  changer 
for  use  with     sub-stage 
condensers  .  .  .277 

—  Some    observations    con- 

cerning sub- stage  illu- 
mination     .  .  .      301 

—  A  trap  for  free- swimming- 

organisms   .  .  .      27!) 

Alveolina   Boscii  .  .  9 

A  mphiplcura      Lindheimcri 

315,  330 
Annual  Report  for  1912  .  113 
1913  .  .  .      354 

—  —1914  .  .  .      558 
Apertometer,  Cheshire's,  an 

improved  form.  E.  31. 
Nelson  .  .  .281 

A  variation  of.    M.  A. 

Ainslie         .  .  .      287 

Apertometers  for  dry  len- 
ses, Two  simple.  F.  J. 
Cheshire       .  .  .      283 

Arachnoidiscus  ornatus,  Ab- 
normal form  of    .  .      414 

arbor icola,  Moraria      .  .      434 

Arrhennrus     Scourfieldi     sp. 

nov.    .  .  .  .139 

Asplachna  Silvestrii    .  .        61 

Jourx.  Q.  M.  C,  Sertes  II. 


Fos- 
mea- 


Asteromphalus  . 
A  hlacodiscus   Combcri,  Ter- 
tiarv  structure  of 


B 

Bacterium  termo,  fiagella  of, 
diameter  of 

Badhamia  utricularis,  Cul- 
tivation of  plasmodia 
of.    A.  E.  Hilton 

Plasmodium  of 

Baker,  W.  E.  Watson, 
sils  from  the  coal 
sures    .... 

Bale,  W.  31.  Notes  on  some 
of  the  Discoid  Diatoms 

Bastian,   Dr.   Charlton 

Bilfingeri,  Callidina     . 

Binocular  Microscopes.  E. 
31.  Nelson   . 

Bi-refrinqence     . 

Borley,  J.  O.  Note  by,  on 
f  ora  minifera  1  dredging  s 

Brachionus,  Description  of 
a  new.     C.  F.  Rousselet 

Brachionus  ytcrodinoid.es  sp. 
nov.    . 

■ — satanicua 

Brown,  N.  E.  Some  notes 
on  the  structure  of  Dia- 
toms .... 

—  Fertilisation      of      Vinca 

minor  ... 

Bryce,  1).  On  five  new 
species  of  Bdelloid  Roti- 
fera    .... 

—  On  five  new  species  of  the 


genus  Habrotrocha 


Brvological 


work,  Micro- 
scopical methods  in. 
G.   T.   Hanis 


PA    K 

35 

577 


391 


381 

585 


41S 

17 

272 

92 


369 
625 

137 

57 

59 
59 

317 
412 

S3 
631 

521 


-No.   77. 


38 


674 


INDEX. 


Burton,  J.  On  the  disc-like 
termination  of  the  fla- 
gellum  of  some  Euglenae 

—  On  a  method  of  marking 

a  given  object  for  future 
reference  on  a  mounted 
slide  .... 

—  Abnormal  form  of  Arach- 

noidiscus  ornatus 

—  Hydrodictyon   reticu  latum 


PACK 


201 


3  1 1 

414 
587 


C 

Cabinet,  Additions  to  the  Club 

401,   646 

Callidina  Bilfingeri  sp.  nov.       92 

Cambrian    strata,    Forami- 

nifera  of  .  .3 

Ceratophyllus  fasciatus,  ana- 
tomy of  .  .441 

Changer  for  sub-stage  con- 
densers.   S.  C.  Akehurst     277 

Cheshire,  F.  J.  Two  simple 
apertometers  for  dry 
lenses  .  .  .      283 

Chiridota  allani  .  .      106 

—  dunedinensis  .  .  106 
Chlamydozoa  .  .  .270 
Clusius  (Charles  de  l'Ecluse. 

1526-1609).  .  .        10 

Condenser,  A  new  low-power. 

E.  M.  Nelson        .  95.  367 

Condensers,      sub- stage,     A 

changer  for  .  .      277 

Conversazione    .  .  .      350 

Copepod,  A   new,    found   in 
water  in  hollows  on  tree- 
trunks.     D.    J.    Scour- 
field    .  .  .  .431 
Correlation  of  characters    .        76 
Coscinodiscus      ...  7 
Coscinodiscus  asterom-phalus .      1 57 

—  heliozoides       .  .        108,331 
Cover-glass,   corrections  for 

thickness  of  .  .      56S 

D 

Dendy,  A.       By-products  of 

organic  evolution  .         65 

-  On  a  new  species  of  Holo- 

thurian        .  .  .105 

-  Organisms  and  Origins  .      259 

-  A  red- water  phenomenon 

due  to  Euglena   .  .      345 

—  The  biological  conception 

of  individuality   .  .      465 


Devil's  Lake,  The  Rotifera 
of.  C.  F.  llousselet 

Diatoms,  Discoid,  Notes  on. 
W.  M.  Bale 

—  Notes  on  the  structure  of 

N.  E.  Brown 
Diatom  structure.  Notes  on 

A.  A.  C.  Eliot  Merlin 
Directions-image.    Bertrand 

lens    . 

—  Becke  lens     . 

—  Interference  colours 

—  Isogvres 
Discoid  Diatoms,  Notes  on 

W.  M.  Bale    . 
Draper,  B.  M.     Dark-ground 
illumination     with     the 
Greenough  Binocular    . 

—  A  live-box  for  the  obser- 

vation   of    insects    and 
similar  objects     . 


E 

Earland,  A.,  s.v.  Heron-  Allen, 
E. 

Eidolic  dots  of  interference 

Eozoon  canadense 

Epidiascope. 

Euglena  viridis,  Theflagellum 
o'         .  .  .  . 

As    a    cause    of     red 

water 

Evans,  J.  W.  The  deter- 
mination of  minerals  un- 
der the  microscope  by 
means  of  their  optical 
characters  . 

Evolution,  organic.  By-pro- 
ducts of.  A.  Dendy 

F 

Fine  adjustment,  side  screw. 
E.  M.  Nelson 

Fissidentaceae,  Notes  on  the 
slides  of.     G.  T.  Harris 

Flagellum  of  some  Euglenae, 
Disc-like  termination  of 
the.  J.    Burton 

flava,   Habrotrccha 

Foraminifera  as  world- 
builders.  E.  Heron- 
Allen  and  A.  Earland    . 

—  From  the  North  Sea,  On 
some.  E.  Heron-Allen 
and  A.  Earland    . 


PA    R 

57 

17 

317 

577 

615 
615 
617 
617 

17 
313 


313 


386 
2 

104 
291 
345 


597 
65 


96 
581 


291 
639 


121 


INDEX. 


G75 


Foraminifera.      Fossil  forms 
from  the  North  Sea 


G 

Gastrotricha.         J.  Murray 

—  Form   and    structure 

—  Haunts  and  habits 

—  Classification 

—  Key  to  genera 

—  List  of  species 

—  Notes  on  certain  species 

—  Bibliography 
G  lobigerina   ooze 

Gordon,  J.  W.  A  "  new  " 
object-glass  by  Zeiss    . 

Grundy,  J.  A  micrometric 
table  by  E.  M.  Nelson  . 


H 

Habrotrocha  flava  sp.  nov 

—  insignis  sp.   nov. 

—  ligula  sp.'nov 

—  longula  sp.  nov. 

—  munda  sp.  nov. 

—  pavida  sp.  nov. 

—  spicula  sp.  nov. 

—  sylvestris  sp.  nov. 

—  torquata  sp.   nov. 
Harris,  G.  T.     The  collectio 

and  preservation  of  the 
Hydroida     . 

—  Microscopical  methods  in 

bryological   work 

—  A   note  on  the   slides   of 

Fissidentaceae    in     the 
■    Q.M.C.  Cabinet   . 

Keath,  C.  E.  Safety  device 
for  use  with  objectives. 

Heron-Allen,  E.,  and  Earl- 
and.  A.  The  Foramini- 
fera in  their  role  as 
world-builders 
—  On  some  Foraminifera 
from  the  North  Sea, 
dredged  b  v  the  Fisheries' 
cruiser  Huxley 

Hilton,  A.  E.  Notes  on  the 
cultivation  of  Plasmodia 
of  Badhamia  utricular  is 

—  Further  notes  on  the  cul- 

tivation of  the  Plasmodia 
of  Badhamia  utricularis 
Hydracarina,  British  :  The 
genus Lebertia.  W.Wil- 
liamson and  C.  D.  Soar 


PAl  i  E 

126 


211 
213 
214 
215 
218 
219 
223 
229 
12 

515 

541 


1)3!) 
635 

90 
640 

85 
637 

89 
637 

87 


143 

521 

581 
344 

1 

121 
381 

585 
479 


Hydrachnida  {vide  Water- 
mites) 

Hydrodictyon  retic  ulatum. 
James  Burton 

Hydroida,  The  collection 
and  preservation  of. 
G.  T.  Harris 

—  Shore  collecting 

—  Preparation  and  mount- 

ing     .... 

—  Notes  on  some  species     . 


illumination,  annular,  for 
sub- stage     . 

—  Dark-ground,    in   the 

Greenough  Binocular   . 

—  New  method  of 

Individuality,  The  biologi- 
cal conception  of.  A. 
Dendy 

Insect    structures,    various. 

E.  M.  Nelson 
insignis,  Habrotrocha  . 
invaginata,   Lagena 

K 

Koristka's  new  "  loup  '* 


Lagenae  of  the  South-west 
Pacific  Ocean.     H.  Side- 
bottom 

Lagena  invaginata  sp.  nov.  . 

—  maculata  sp.  nov.  . 

—  renifonnis  sp.  nov. 

—  splendida  sp.  nov. 
Lebertia  (Hydracarina) 
Lebertia  celtica  . 

—  fimbria  ta 

—  glabra    .... 

—  Halberti 

—  insignis 

—  obscura 

—  porosa   .... 

—  Soari     .... 

—  stigmatifera    . 

—  tau-insignita . 

—  trisecta 

Leitz  concentric  reflecting 
condenser    . 

Lewis,  R.  T.  The  early  his- 
tory of  the  Quekett 
Microscopical  Club 


IW.K 


587 


143 
144 

149 
152 


301 

313 
365 


465 

593 
635 

204 


2.-,j 


161 

204 

206 

204 

178 

479 

494 

491 

507 

505 

497 

504 

499 

491 

509 

487 

512 

303 


425 


676 


INDEX. 


i'.V  E 

Lhwyd,  Edward  .  .      259 

Library,    Recent     additions 

to  ...      390 

ligula,  Habrotrccha      .  .        90 

Live-box  for  observation  of 

insects  .  .  .313 

longitarsus,  Acercus     .  .140 

longula,  Habrotrocka  .  .      040 


.M 


maculata,  Lagena         .  .      206 

Magnifying  power  of  a  mi- 
croscope, Measuring  the. 
E.  M.  Nelson       .  .239 

—  of  objectives.  Initial  mea- 

surement of.  E.  M. 

Nelson  .  .  .295 

Marking  an  object  slide  for 

future  reference  .      311 

Measures,  English  metrical 
table  for  the  conversion 
of  .  .  .      424 

Merlin,  A.  A.  C.  Eliot,  Se- 
condary hairs  on  foot  of 
a  Ceylon  spider   .  .      252 

—  On  the  minimum  visible     385 

—  Notes  on  diatom  structure  577 
Micrometric  table  .  .541 
Microscope  construction,  On. 

E.  M.  Nelson       .  .        96 

—  new  model.     W.  Watson 

&  Sons,  Ltd.         .  .      108 

Microscopes,  Binocular         .      369 
Minchin,   E.   A.      Some  de- 
tails in  the  anatomy  of 
the      rat-flea      (Ccrato- 
phyllus  fasciatus  .      441 

Minerals,  Determination  of, 
by  means  of  their  optical 
characters.  J.  W. 

Evans  .  .  .      597 

Minimum  visible,  The  270,  385 
"Mixon  "  reef,  Selsey  .  9 

Monera      .  .  .  .268 

Moraria  arboricola  sp.  nov.  434 
Mosses,    Collecting      .  .521 

—  Preparation  of  slides      .      523 

—  Notes  on  slides  of  533,  581 
munda,  Habrotrocha  .  .  85 
Murray,  J.     Gastrotricha     .      211 

N 

Navicula  rhomboides  .  96,  315 

—  serians  .  .  .329 


PAGE 

Nelson,  B.  M.     A  new  low- 
power   condenser  .        95 

—  On  microscope  construc- 

tion and  the  side  screw 

fine  adjustment  .  .        96 

—  Navicula  rhomboides  and 

allied  forms  .  .        90 

—  Note  on  Pleurosigma  an- 

gwlatum       .  .  .98 

—  Actinocycliis    Ralfsii  and 

a  coloured  coma  .      100 

—  On  a  new  method  of  mea- 

suring the  magnifying 
power  of  a  microscope     230 

—  An     improved    form    of 

Cheshire's    apertometer     281 

—  On  the  measurement  of 

the  initial  magnifying 
powers  of  objectives     .      295 

—  Amphipleura  Lindheimeri     3 1 5 

—  A    new    object-glass    by 

Zeiss  and  a  new  method 

of  illumination    .  .363 

—  A    new    low-power    con- 

denser .  .  .367 

—  Binocular  microscopes    .      369 

—  Palaeozoic  fungi     .  .      546 

—  Various  insect  structures  593 
Nitzschia  scalaris  .  .  330 
Notices  of  Books  :    Marcus 

Hartog.  Problems  of 
Life  and  Reproduction       101 

—  C.    E.    Heath.     The   Be- 

ginner's Guide  to  the 
Microscope  .  .      102 

—  H.    Lloyd  Hind  and  W. 

Brough Randies.  Hand- 
book of  Photomicro- 
graphy        .  .  .      339 

—  J.  Cash  and  G.  H.  Wailes. 

British  Freshwater 

Rhizopoda,  vols,  i.-iii. 
(Ray  Society)      .  .      643 

Nummulitic  limestone  .  9 

O 

Obituary  Notices  : 

Rt.      Hon.      Sir     Ford 

North  .  .      258 

Dr.  M.  C.  Cooke  .  .      422 

F.  W.  Millett       .  .      559 

Prof.  E.  A.  Minchin     .      669 

Object-glass  by  Zeiss,  A  new. 

E.  M.  Nelson       .  .      363 

A  "  new."  J.  W. 

Gordon        .  .  .515 


INDEX 


677 


Object-image,  examination 
of        . 

—  Extinctions   . 

—  Pleochroism  . 

—  Relative  retardation 

—  Quartz  wedge 

—  Gypsum  plate 

—  Mica  steps 
Objective,    An    addition   to 

th^.  M.  A.  Ainslie 

O'Donohoe,  T.  A.  The  min- 
ute structure  of  Coscino- 
di  sc  u  s  asteromphalus 
and  of  the  two  species 
of  Pleurosigma,  P.  angu- 
latum  and  P.  balticum  . 

—  An    attempt    to    resolve 

and  photograph  Pmnw- 
laria  nobilis 

Oil-immersion  into  water- 
immersion,  Conversion 
of 

Organisms  and  Origins.  A. 
Dendy 

—  Filter-passing 

—  Terrestrial,  their  origin   . 
Osmotic  growths,  Artificial. 


IW.F. 

601 

601 

(KM 

CO.-) 

608 

(ill 
612 

561 


155 


300 


572 

250 
270 
264 

78 


Palaeozoic  fungi  .  .      546 

Panspermia,  Theory  of        .      264 
pavida,  Habrotrocha    .  .      637 

Pedalion  ou  Pedalia.     C.  F. 

Rousselet    .  .  ,397 

Pinnularia  major         .  .      317 

—  nobilis  .  .  .309 
An  attempt  to  resolve 

and  photograph.  T. 

A.   O'Donohoe      .  .      300 

Plasmodia,  Cultivation  of 

381,  585 

—  reversing    currents,    Ex- 

hibition of  .  .  .      383 

Plasmodium  of  B.  utricular  is, 

Cultivation  of.       A.  E. 

Hilton  .  .  .      585 

Pleurosigma  angulatum 


Proceedings.        Oct.   1913- 
Feb.   1914  . 

—  Mar.   1914 — Tunc  1914 

—  Oct.    1914— Feb.    1915 

—  Mar.    1915 — lune  1915 
pterodinoides,   Brachiou us 


Q 

Quekett  Microscopical  Club, 
Early  History  of.    R.  T. 


Lewis 
—  History 


of 


R 


PAGE 

340 
41  1 
537 
653 
59 


425 
419 


98,    159, 

325 

—  balticum        .           .        159, 

319 

President's    Address,    1913. 

Arthur    Dendy    . 

65 

1914.     Arthur  Dendy 

259 

1915.     Arthur  Dendy 

465 

Proceedings.       Oct.    1912 — 

Feb.  1913   . 

103 

—  Mar.   1913— June  1913    . 

245 

Rat-flea,  some  details  in  the 
anatomy  of.  E.  A. 

Minchin       .  .  .441 

—  abdominal    nervous    sys- 

tem   ....      447 

—  dissection  of  .  .442 

—  female    reproductive    or- 

gans .  .  .      457 

—  male  reproductive  organs     452 

—  preparation  of  tissues     .      443 

—  salivary  glands      .  .      450 

—  stellate  muscles  in  oeso- 

phagus        .  .  .460 

Ray.   John.    Three   Physico- 

Theological  Discourses  .      259 
Refractive  index         .  .      625 

reni  for  mis,  Lagena      .  .      204 

Report    on    the    Conference 

of  Delegates  (Havre)        .      395 
Rhabdites  .  .  .46 

Rhabdocoelida.  British 

Fresh-water.   H.  White- 
head .  .  .45 
Rotifera    of    Devil's    Lake. 

C.  F.  Rousselet    .  .        57 

—  Bdelloid,  Five  new  species 

of.  D.  Brvce     83,  631 

Rousselet,  C.  F.  The  Roti- 
fera of  Devil's  Lake, 
with  Description  of  a 
new  Brachionus  .  .        57 

—  Remarks  on  two  species 

of  African  Volvox         .      393 

—  Report  on  the  Conference 

of  Delegates  of  Corre- 
sponding Societies  held 
at  Havre     .  .  .      395 

—  Pedalion  ou  Pedalia  :  une 

question  de  nomencla- 
ture dans  la  classe  des 
Roti  feres     .  .  .397 


078 


INDEX. 


PACE 


S 

Scourfield,   D.    J.      A    new 

Copepod        found        in 

water  from  hollows  in 

tree  trunks 
Scourfieldi,   Arrhcnurus 
Sidebottom,  H.      Lagenae  of 

the  South-west    Pacific 

Ocean    (Supplementary 

Paper) 
Soar,  C.  D.      Description  ot 

Arrhcnurus     Scourfieldi 

and  Acercus  longitarsus. 

Two     new     species     of 

water- mites 

—  s.v.  Williamson,  W. 
Sperchon,    the    genus,  New 

records  for  . 
"  Spheres  "  from  the  chalk 
spicula,  Habrotrocha   . 
splendida,  Lagena 
Sponge-spicules,   Shape  and 

evolution  of 

—  scleroblasts  and  mother- 

cells   .... 

—  specific  differences 
Spontaneous         generation, 

Theory   of  . 
Stauroneis  phoenicentron 
Surirella  gemma 
sylvestris,  Habrctrccha 

T 

Tabanus  bovinus 

Taeniogyrus  Allani 

Test  objects,  Diatoms  first 
used  as 

torquata,  Habrotroch'i 

Trap  for  free-swimming  or- 
ganisms. S.  C.  Ake- 
hurst 


431 
131) 


161 


139 


141 

8 

89 

178 

67 

73 
74 

205 
331 
327 
637 


595 
10G 

579 

87 


279 


Travis,  W.  R.  Simple  ap- 
paratus in  pond- hunt- 
ing     . 

—  On  quartz  crystals . 
Treasurer's  Report  for  1912 

1913 

1914 

Triceratium  favus 
Trichodina  pedicvlus  . 

—  Steinii 

Trichopteryx  atomaria 
Trochodota  dunedincnsis 
Tube-length,  correct,  Impor- 
tance of 

Turbellaria  {vide  Rhabdo- 
coelida) 

V 


PA.aH 


256 

348 
120 
354 
558 
332 
545 
545 
595 
105 

562 


413 


Vinca  minor,  Fertilisation  of 
Volvox,  African,  Two  species 

of.  C.  F.  Rousselet     393 

Volvox  africanns  .  .393 

—  Rousseleti       .  .  .      394 


W 

Water-mites,  Description  of 
two  new  species.  C.  D. 
Soar  .... 

l' Wheel-plates "  in  Holo- 
thurians.  Development 
of         ...  . 

Whitehead,  H.  Some  notes 
on  British  freshwater 
Rhabdocoelida,  a  group 
of  Turbellaria 

—  An  epizoic  Infusorian     . 

Williamson,  W.,  and  Soar,  C 
D.     British    Hydrocar- 


139 


106 


45 

545 


ina  :  the  scenus  Lebertia     479 


OEEICERS    AND    COMMITTEE. 

{Elected  February  1914.) 


President: 

Prof.  Arthur  Dendy,  D.Sc,  F.R.S. 

Vice-Presidents  : 

C.  F.  Rousselet,  Curator  R.M.S. 

Edmund  J.  Spitta,  L.R.C.P.,  M.R.C.S.,  F.R.M.S.,  F.R.A.S. 

D.  J.  Scourfield,  F.Z.S.,  F.R.M.S. 

Prof.  E.  A.  Minchin,  M.A.,  Ph.D.,  F.R.S. 

COIVIIVIITTEE  : 


C.  H.  Bestow,  F.R.M.S. 

M.  Blood,  M.A.,  F.C.S.,  F.R.M.S. 
N.  E.  Brown,  A.L.S. 

D.  Bryce. 

J.  Grundy,  F.R.M.S. 

E.  Heron-Allen,     F.R.M.S., 
F.L.S.,  F.Z.S.,  F.G.S. 


R.  Inwards,  F.R.A.S. 

A.  Morley  Jones. 

J.  M.  Offord,  F.R.M.S. 

R.  Paulson,  F.L.S.,  F.R.M.S. 

C.  D.  Soar,  F.L.S.,  F.R.M.S. 

J.  Wilson,  F.R.M.S. 


Hon.  Treasurer : 

Frederick  J.   Perks,  48,   Grove  Park,  Denmark  Hill,  S.E., 
to  whom  subscriptions  should  be  sent. 

Hon.  Secretary: 

James   Burton,    8,    Somali   Road,    West   Hampstead,   N.W., 
to  whom  all  correspondence  should  be  addressed. 

Hon.  Assistant  Secretary: 

J.  H.  Pledge,  F.R.M.S.,  72,  Nibihwaite  Road,  Harrow,  Middlesex. 

Hon.  Sec.   for  Foreign  Correspondence: 

C.  F.  Rousselet,  Curator  R.M.S. ,  Fir  Island,  Mill  Hill,  N.W. 

Hon.  Reporter  : 

R.  T.  Lewis,  F.R.M.S.,  41,  The  Park,  Ealing,  W. 

Hon.  Librarian  : 

S.  C.  Akehurst,  F.R.M.S.,  60,  Bowes  Road,  Palmers  Green,  N. 

Hon.  Curator  : 

C.  J.  H.   Sidwell,  F.R.M.S.  46,  Ashbourne  Grove,  Dulwich,  S.E. 

Hon.   Editor  : 
A.  W.   Sheppard,  F.Z.S.,  F.R.M.S.,   1,    Vernon  Chambers,   W.C. 
a 


11 


PAST     PRESIDENTS. 


Elected 

July  1865. 
.,      1866. 


?  ? 


/? 


JS 


}J 


1867-8. 

1869. 

1870-1. 

1872-3. 

1874-5. 

1876-7. 

1878. 

1879. 


♦EDWIN  LANKESTER,  M.D.,  F.R.S.  . 
♦ERNEST  HART  .... 

♦ARTHUR  E.  DURHAM,  F.R.C.S.,  F.L.S. 
♦PETER  LE  NEVE  FOSTER,  M.A.      . 
♦LIONEL  S.  BEALE,  M.B.,  F.R.S. 
ROBERT  BRAITHWAITE,  M.D.,  F.L.S. 
♦JOHN  MATTHEWS,  M.D.,  F.R.M.S.   . 
♦HENRY  LEE,  F.L.S.,  F.G.S.,  F.R.M.S.,  F.Z.S 
♦THOS.  H.  HUXLEY,  LL.D.,  F.R.S.    . 
♦T.    SPENCER    COBBOLD,     M.D.,     F.R.S 

T  .L.O.     ...... 

T.   CHARTERS   WHITE,   M.R.C.S.,   L.D.S 
F.R.M.S.       ..... 

M.  C.  COOKE,  M.A.,  LL.D.,  A.L.S.     . 
♦W.  B.  CARPENTER,  C.B.,  F.R.S. 

A.  D.  MICHAEL,  F.L.S.,  F.R.M.S.       . 

B.  T.  LOWNE,  F.R.C.S.,  F.L.S.  . 
*Rev.   W.   H.   DALLINGER,   LL.D.,   F.R.S. 

x  .R.M.S.        ..... 

EDWARD  MILLES  NELSON,  F.R.M.S. 
*J.  G.  WALLER,  F.S.A. 
JOHN  TATHAM,  M.A.,  M.D.,  F.R.M.S. 
GEORGE  MASSEE,  F.L.S.  .         .       Feb.  1900-1-2-3. 

EDMUND   J.   SPITTA,   L.R.C.P.,   M.R.C.S., 

F.R.A.S.,  F.R.M.S.         ,         .         .       Feb.  1904-5-6-7. 
E.  A.  MINCHIN,   M.A.,  F.R.S.        .         .     Feb.  1908-11 

*  Deceased. 


5> 


J5 


1880-1. 

1882-3. 
1884. 
„  1885-6-7. 
Feb.  1888-9. 

„  1890-1-2. 

„  1893-4-5. 

„      1896-7. 

1898-9. 


J5 


Ill 


HONORARY    MEMBERS. 


Date  of  Election. 


Jan.  24,  1868.     Arthur  Mead  Edwards,  M.D. 

423,     Fourth    Avenue,     Newark,     New 
Jersey,  U.S.A. 

Feb.  17,  1S93.     Robert  Braithwaite,  M.D.,  F.L.S.,  F.R.M.S. 

{Past  President) 
26,  Endymion  Road,  Brixton  Hill,  S.W. 

Feb.  17,  1893.     M.    C.    Cooke,    M.A.,    LL.D.,    A.L.S.    {Past 

President) 

38,  Lindley  Avenue,  East  Southsm,  Hants. 

Feb.  17,  1893.     T.  Charters  mite,  M.R.C.S.,L.D.S.,  F.R.M.S. 

(Past  President) 

49,  Victoria  Road  South,  Southsea. 

Mar.  19,  1897.     B.  T.  Lowne,  M.D.,  F.R.C.S.,  F.L.S.  (Past 

President) 

91,  Carlisle  Road,  Hove,  Sussex. 

May  18,  1906.     Dr.  Eugene  Penard 

Rue  Topfjer  3,  Geneva. 

Jan.  23,  1912.     Alpheus  Smith 

14,  Leigham  Vale,  Streatham,  S.W, 

April  23,  1912.     Fred  Enock,  F.L.S.,  F.R.M.S.,  F.E.S. 

13,  Tufnell  Park  Road,  Holloway,  N. 


IV 


LIST    OF    MEMBERS. 


Date  of  Election. 


Feb.  16,  1906.     Abson,  Herbert 

14,  Gainsborough  Road,  Mile  End,  E. 
Dec.  23,  1913.     Ainslie,     Maurice     Anderson,     R.N.,     B.A., 

F.R.A.S. 

8,  Woodville  Road,  Blackheath  St. 
Feb.  16,  1906.     Akehurst,  Sydney  Charles,  F.R.M.S.    (Hon. 

Librarian) 

60,  Bowes  Road,  Palmer's  Green,  N. 
Feb.  19,  1904.     Allardice,  Lieut.  William  McDiarmid 

Tregenna  Longer oss,  St.  Endellion  Norths 
Cornwall. 
May  24,  1910.     Allen,  William  Nassau 

"  Caerneagh,"     North     Circular    Road> 
Dublin. 
Jan.  28,  1913.     Allison,  Arthur  Morris 

8,  Sidney  Road,  Beckenham. 
Dec.  15,  1899.     Angus,  H.  F.,  F.R.M.S. 

83,  Wigmore  Street,  Cavendish  Square,  W+ 
Mar.  24,  1914.     Anthes,  Ernst  Hermann 

21,  Lancaster  Road,  Hampstead,  N.W. 
Feb.  25,  1913.     Armitage,  John  Joseph,  L.D.S.E. 

5,  Cavendish  Place,  W. 
June  21,  1907.     Arpin,  John  Edward 

131,  Castelnau,  Barnes,  S.W. 
Feb.  22,  1889.     Ashe,  A.,  F.R.M.S. 

55,  Warrior  Square,  Southe?id-on-Seai 
Feb.  28,  1911.     Austin,  Henry 

Tudor    House,     120,     Greenwich    Road> 
Greenwich,  S.E. 


Date  of  Election. 

*       . 

June    4,  1909.     Baddeley,  William  H.  L. 

29,  Church  Crescent,  Church  End,  Finch- 
ley,  N. 
April  17,  1903.     Bagshaw,  Walter,  J.P.,  F.R.M.S. 

"  Moor  field,"  Birkenshaw,  near  Bradford, 
Yorks. 
Sept.  26,  1884.     Baker,  F.  W.  Watson,  F.R.M.S. 

313,  High  Holborn,  W.C. 
Mar.  16,  1906.     Baker,  Henry  James 

13,  Moorgate  Street,  E.G. 
April  2,  1909.     Baker,  Wilfred  E.  Watson 

313,  High  Holborn,  W.C. 
Nov.  25,  1913.     Bale,  Wm.  Urontier,  F.R.M.S. 

63,    Walpole  Street,  Kew,  Victoria,  Aus- 
tralia. 
June  19,  1908.     Banhani,  Edward  Elliott 

128,  Uxbridge  Road,  West  Ealing,  W. 
May  28,  1912.     Barnard,  Edward  Jas. 

10,  Denver  Road,  Stamford  Hill,  N. 
Feb.  25,  1913.     Barnard,  Joseph  Edwin,  F.R.M.S. 

Park  View,  Brondesbury  Park,  N.W. 
Mar.  19,  1886.     Barnes,  W. 

23,  Jackson  Road,  Holloway,  N. 
May  28,  1912.     Barratt,  Kenneth  Franklin 

"  Bell  Moor,"  Hampstead  Heath,  N.W. 
May  28,  1912.     Barratt,  Thos.  Franklin 

"  Bell  Moor,"  Hampstead  Heath,  N.W. 
Sept.  27,  1872.     Bartlett,  Edward,  L.D.S.,  M.R.C.S.E. 

38,  Connaught  Square,  W. 
Nov.  26,  1912.     Bassett,  Ernest  Henry 

"  Pro    tern,"    Amberley   Road,   Palmer's 
Green,  N. 
June  17,  1892.     Bates,  C. 

1,  Windsor  Road,  Denmark  Hill,  S.E. 
Oct.  18,  1895.     Baugh,  J.  H.  A. 

63,  Bambridge  Road,  Hammersmith,  W . 
June    4,  1909.     Baxendale,  Frederick  G. 

22,  Holmesdale  Avenue,  East  Sheen. 
Jan.  16,  1891.     Baxter,  W.  E.,  F.R.M.S, 

170,  Church  Street,  Stoke  Newington,  N. 


VI 

Date  of  Election. 


June  19,  1908.     Bayliffe,  John  H. 
Nov.  26,  1875.     Beaulah,  John 

Albert  House,  Brigg. 
July  25,  1884.     Beck,  C,  F.R.M.S. 

68,  Comhill,  E.G. 
Nov.  26,  1912.     Bellamy,  Geo.  Claxson 

16,  Great  Ormond  Street,  W.C. 
June  27,  1911.     Bennett,  Lionel  C. 

49,  Erpingham  Road,  Putney,  S.W. 
Feb.  16,  1906.     Bestow,  Charles  H.,  F.R.M.S. 

43,  Upper  Clapton  Road,  N.E. 
June  16,  1905.     Blair,  William  Nisbet 

23,  West  Hill,  Highgate,  N. 
Oct.     2,  1908.     Blockley,  Edgar  A. 

26,  Mayfield  Avenue,  Chiswick,  W. 
May  19,  1899.     Blood,  Maurice,  M.A.,  F.C.S.,  F.R.M.S. 

8,  Chichele  Road,  Cricklewood ,  N.W. 
Feb.  25,  1913.     Booker,  Alfred  James 

37,  Claremont  Road,  Highgate,  N. 
April  25,  1911.     Bowtell,  Alexander  Jas. 

123,  Dalston  Lane,  N.E. 
Nov.  15,  1907.     Bradford,  William  Barnes 

65,  Tyrwhitt  Road,  St.  John's,  S.E. 
Nov.  17,  1905.     Bremner,  John  Unthank 

277,  King  Street,  Hammersmith,  W. 
Jan.  24,  1911.     Bridge,  Samuel 

28,  Larkhall  Rise,  Clapham,  S.W. 
Nov.    6,  1908.     Broad,  John  Moxon 

2,  Nicoll  Road,  Harlesden,  N.W. 
May  28,  1912.     Brooke,  Thos.  Robinson 

12,  Warren  Road,  Chingford,  N.E. 
Dec.    4,  1908.     Brooks,  Theodore,  F.R.M.S. 

British  Vice-Consul,  Guantanamo,  Cuba. 
Dec.  19,  1890.     Brough,  J.  R. 

"  Eversley,"  Shepherd's  Hill,  Highgate,  N. 
Mar.  15,  1907.     Browett,  William 

"  Beaumont,"     Pear  field    Road,     Forest 
Hill,  S.E. 
May  24,  1910.     Brown,  Edward  George 

8,  Freke  Road,  Battersea,  S.  W. 


VI 1 


Date  of  Election. 


Jan.  18,  1907.     Brown,  Nicholas  Edward,  A.L.S. 

6,  The  Avenue,  Kew. 
Jan.  28,  1887.     Browne,  E.  T.,  M.A.,  F.R.M.S. 

Anglefield,  BerkJiamsted,  Herts. 
Mar.  18,  1904.     Brushfleld,  N.  W. 

13,  All  farthing  Lane,  Wandsworth  Com- 
mon, S.W. 
Jan.  15,  1892.     Bryce,  David 

37,  Brooke  Road,  Stoke  Newington,  N. 
May  28,  1912.     Bull,  Albert  Edwd. 

3,  Canterbury  Terrace,  Sudbury,  Harrow, 
May  23,  1911.     Bunnin,  Charles  A. 

113,  Newlands  Park,  Sydenham,  S.E. 
May  15,  1908.     Bunting,  Percival  J. 

"  Lyndhurst,"  Birches  Barn  Road,  WoU 
verhampton. 
Jan.  20,  1905.     Burnell,  Charles  Edward 

29,  High  Street,  Shepton  Mallet. 
Feb.  28,  1913.     Burns,  Dr.  Xesbitt,  M.B.,  B.A.,  F.R.S.E. 

"  The  Lodge,"  Highbridge,  Somerset. 
April  20,  1906.     Burrell,  T.  Leonard 

20,  Upper  Homsey  Rise,  Islington,  N. 
Feb.  19,  1904.     Burton,  James  (Hon.  Sec), 

8,  Somali  Road,  West  Hampstead,  N.W. 
Jan.  24,  1911.     Butcher,     Thomas     William,    M.B.,     CM., 

F.R.M.S. 

3,  Clifton  Street,  Blackpool. 
Feb.  19,  1904.     Butterworth,  Arthur  Cyrus,  F.R.M.S. 

Glanville,  Crowstone  Road,   Westcliff-on* 
Sea. 


April  15,  1904.     Caffyn,  Charles  Henry, 

32,  Falkland  Road,  Homsey,  N. 
June  18,  1897.     Campbell,  Colney 

47,  Selborne  Road,  Southgate,  N. 
Mar.  16,  1906.     Capell,  Bruce  John,  F.R.M.S. 

10,  Castelnau,  Barnes,  S.W. 
Mar.  28,  1914.     Carlile,  E. 

28,  Chatsworth  Road,  Croydon. 


vm 

Date  of  Election. 


Jan.  20,  1905.     Carrington,  John  / 

P.O.     Box    48,    East     London,     South 
Africa. 
May  24,  1910.     Carruthers,  Ferdinand  Gilbert 

10,  Addison  Road,  Bedford  Park,  W. 
Jan.  25,  1910.     Carter,  John  Arthur 

6,  Temple  Road,  Stowmarket. 
June  17,  1892.     Chaloner,  G.,  F.C.S. 

South  Street,  Colyton,  S.O.,  Axminster. 
Mar.  17,  1905.     Chapman,  David  Leighton 

100,  Tooley  Street,  S.E. 
June  28,  1910.     Charlton,  Alfred  Edward 

13,  Parkhurst  Road,  Camden  Road,  N. 
Oct.  26,  1909.     Cheavin,  Harold  Squire,  F.R.M.S.^ 

70,  Somerset  Road,  Hudders field. 
April  22,  1913.     Cheshire,  Frederic  John,  F.R.M.S. 

23,  Carson  Road,  Dulwich,  S.E. 
Mar.  22,  1878.     Chester,  The  Very  Rev.  the  Dean  of 

The  Deanery,  Chester. 
Dec.  18,  1896.     Chipps,  F.  W. 

201,  Castelnau,  Barnes,  S.W. 
Jan.  20,  1905.     Christie,  John,  F.R.M.S. 

Henleigh,  Kingston  Hill,  Surrey. 
May  18,  1906.     Churchouse,  G. 

30,  Natal  Road,  Bowes  Park,  N. 
Mar.  17,  1905.     Clemence,  Walter 

Farringford,  Walton-on-Thames. 
Jan.  27,  1914.     Clibborn,  Lt.-Col.  John 

87,  Victoria  Street,  S.W. 
Oct.  18,  1907.     Coldwells,  William  Henry 

Redcote,  Shirley  Road,  Wallington. 
Jan.  28,  1913.     Coles,  Alfred  C,  M.D.,  D.Sc,  F.R.S.E. 

"  York    House,'"    Poole    Road,    Bourne- 
mouth. 
Mar.    5,  1909.     Collier,  Oswald 

The  Hermitage,  Snaresbrook. 
Nov.  16,  1906.     Collins,  Brenton  Robie,  M.A. 

Gorsebrook,  Tunbridge  Wells,  Kent. 
Oct.  21,  1904.     Conrady,  Alexander  Eugen,  F.R.A.S. 

23,  Flanchford  Road,  Stamford  Brookt  W. 


IX 

Date  of  Election. 

Mar.  25,  1913.     Cook,  John  Thomas 

106,     Thurlow     Park     Road,     Dulwich, 
S.E. 
Nov.  26,  1912.     Coon,  Joseph  May 

"  Morwenna"  St.  Austell. 
April  20,  1906.     Couch,  Robert  Percy 
Jan.  18,  1901.     Cox,  Thomas  N. 

104,  Tressillian  Road,  Brockley,  S.E. 
Jan.  15,  1904.     Cox,  William 

"  The  Pound,"  Ling  field,  Surrey. 
June  19,  1903.     Coxhead,  G.  W. 

5a,  Springfield  Gardens,  Upper  Clapton, 
N.E. 
Jan.  25,  1910.     Crabtree,  James  Fox,  B.A. 

40,  Brazennose  Street,  Manchester. 
Dec.  20,  1901.     Craig,  Thomas,  F.R.M.S. 

26,  Selkirk  Avenue,  Montreal,  Canada. 
Nov.  25,  1913.     Creese,  Edward  J.  E.,  F.Z.S.,  F.R.M.S. 

29,  Cornford  Grove,  Balham,  S.W. 
Nov.  21,  1902.     Cressey,  Dr.  G.  H. 

Oak  Manor,  Tonbridge. 
Aug.  28,  1868.     Crisp,    Sir    Frank,    LL.B.,    Y.P.L.S.,    B.A., 

F.R.M.S.,  F.G.S.,  F.Z.S., 

5,  Lansdowne  Road,  Notting  Hill,  IV. 
Mar.  20,  1908.     Croger,  Frank  Clifford 

114,  Wood  Street,  E.G. 
Nov.  16,  1906.     Crosbie,  Walter 

Kenilworth,     Lyonsdoivn    Avenue,    New 
Bar  net. 
Jan.  25,  1910.     Cross,  Edward 
Feb.  16,  1900.     Crossland,  R,  E.,  A.R.I.B.A. 

10,  Serjeant's  Inn,  Fleet  Street,  E.G. 
Mar.  16,  1894.     Culshaw,  Rev.  George  H.,  M.A. 

The  Rectory,  Iver  Heath,  Bucks. 
June  25,  1880.     Curties,  C.  Lees,  F.R.M.S. 

244,  High  Holborn,  W.G. 
Jan.  16,  1903.     Curties,  C.  L.,  jun. 

244,  High  Holborn,   W.G. 
May  18,  1906.     Cuzner,  Edgar,  F.R.M.S. 

36,  Trothy  Road,  Bermondsey,  S.E. 


X 

Date  of  Election. 

Nov.  18,  1904.     Dade,  Willoughby  Dreyer 

13,  Glendinning  Avenue,  Weymouth. 
Jan.  17,  1908.     Dallas,  Charles  Caldwell,  F.R.G.S.,  F.Z.S. 

Eastley  Wootion,  New  Milton,  Hants. 
Dec.  21,  1906.     Darlaston,  Herbert  William  Hutton 

31,  Freer  Road,  Birchfield,  Birmingham. 
Feb.  28,  1911.     Davidson,  John 

29,     Federation     Road,     Abbey     Wood, 
Kent. 
Nov.  22,  1910.     Davidson,  Rev.  Martin,  M.A.,  B.Sc.,  F.R.A.S. 

56,  Hudson's  Road,  Canning  Town,  E. 
June  16,  1905.     Davies,  Daniel,  F.R.M.S. 

12,  Eliot  Hill,  BlacJcheath,  S.E. 
April  28,  1911.     Davies,  Daniel  Arthur 

12,  Eliot  Hill,  BlacJcheath,  S.E. 
Jan.  19,  1906.     Davies,  Perceval  Eckton 

Abbeydale,  Marmora,  Road,  Honor  Oak, 
S.E. 
June  24,  1913.     Dean,  Frank 

1,  Langham  Street,  Portland  Place,  W. 
May  17,  1901.     Deeley,  George  P. 

Moushall,  Amblecote,  Brierley  Hill,  Staf- 
fordshire. 
April  19,  1895.     Delcomyn,  Theo.  A.,  F.R.M.S. 

"  Feldheim,"  Wimbledon  Common,  S.W~ 
Jan.  23,  1912.     Dendy,  Arthur,  D.Sc,  F.R.S.  (President) 

Vale  Lodge,  Hampstead  Heath,  N.W. 
Nov.  17,  1893.     Dennis,  A.  W. 

56,  Romney  Buildings,  MilbanJc,  S.W. 
Mar.  22,  1889.     Dick,  J. 

Milber,  Victoria  Road,  Mill  Hill,  N.W. 
Feb.  15,  1907.     Dilks,  Arthur  Charles,  B.Sc. 

Tardebigge,  Bromsgrove. 
June  24,  1913.     Dinn,  Harold  H. 

72,  Elmwood  Road,  Heme  Hill,  S.E. 
June    4,  1909.     Dixon,  Arthur  L. 

35,  North  Hill,  Highgate,  N. 
June  17,  1892.     Dixon-Nuttall,  F.  R.,  F.R.M.S. 

"  Ingleholme,"    Eccleston    Park,    near 
Prescot,  Lancashire. 


XI 


Date  of  Election. 


Nov.  25,  1913.     Dobell,  Henry 

74,  Babbacombe  Boad,  Bromley,  Kent. 
Feb.  22,  1910.     Doughten,  William  S. 

415,     Bace     Street,     Philadelphia,     Pa.y 
U.S.A. 
Oct,  25,  1910.     Douglas,  William 

Grafton  House,  Berkhamsted,  Herts. 
Oct.  24,  1911.     Downing,  Owen  Walter 

23,  Glenhouse  Boad,  Eltham,  Kent. 
Mar.  17,  1899.     Downs,  Arthur 

2,  Ulverston  Boad,  W althamstow ,  E. 
Nov.  23,  1909.     Draper,  Bernard  M. 

9,  Pitt  Street,  Kensington,  W. 
May  17,  1907.     Drinkwater,  Jesse,  F.R.M.S. 

St.    Margaret's,   Stanley   Gardens,    Wal- 
lington. 
Nov.  15,  1901.     Druett,  C.  R. 

330,  TJxbridqe  Boad,  W. 
Dec.  28,  1909.     Dumat,  Frank  C. 
Feb.  22,  1910.     Dunstall,  George  Kirkman,  F.R.M.S. 

82,  Darenth  Boad,  Stamford  Hill,  N. 
Feb.  25,  1913.     Durrad,  John  Wm,  F.R.A.S. 

350,  Fosse  Boad  North,  Leicester. 


June  19,  1891.     Earland,  Arthur,  F.R.M.S. 

34,  Granville  Boad,  Watford. 
May  15,  1908.     East,  John  Holtham 

75,  Moorland  Boad,  Weston-super-Mare, 
Sept,  25,  1868.     Eddy,  J.  R.,  F.R.M.S.,  F.G.S. 

The  Grange,  Carleton,  Skipton,  Yorkshire. 
April  22,  1913.     Edwards,  Henry 

22,  Carnarvon  Boad,  Beading. 
Oct.  22,  1912.     Edwardes,  Seabury 

Pegu,  Lower  Burma. 
Feb.  21,  1902.     Edwards,  Thomas  Jarvis 

9,  St.  Lawrence  Boad,  Brixton,  S.W. 
Oct.  22,  1912.     Elliott,  Wm. 

97,  Devonport  Boad,  Shepherd's  Bush,  If. 


Xll 

Date  of  Election. 

Mar.  22,  19L0.     Ellis,  William  Neale 

The    '  Pharmacy "  Appledore,  Devon. 
Nov.  28,  1911.     Emsley,  Harold  Percy 

31,  Victoria  Road,  Wood  Green,  N. 
Mar.  24,  1914.     Engelhardt,  Conrad  Wm. 

6,  Shaftesbury  Villas,  Kensington,  W . 
Feb.  28,  1879.     Epps,  Hahnemann 

95,  Upper  Tulse  Hill,  Brixton,  S.W. 
Dec.  20,  1907.     Evans,  Benjamin 

162,  Batter  sea  Bridge  Road,  S.W. 
Nov.  17,  1905.     Evans,  Morris  B. 

33,     Lady    Margaret    Road,     Southall, 
Middlesex. 

Dec.  21,  1906.     Fawcett,  Henry  Hargreave 

Thomcombe,  near  Chard,  Somerset. 
June  24,  1913.     Fendich,  Ernest  Alfred 

22,      Finedon      Road,      Wellingborough, 
Northants. 
June  16,  1893.     Filer,  Frank  E. 

35,  Dancroft  Road,  Heme  Hill,  S.E. 
Feb.  19,  1904.     Finlayson,  Daniel 

"  Red/em,"  Pellatt  Grove,  Wood  Green,  N. 
Feb.  24,  1914.     Finlayson,  Raymond 

22,  Pellatt  Grove,  Wood  Green,  N. 
June  19,  1908.     Flamank,  Sydney  W. 

Church    House,     Dean's      Yard,     West- 
minster,  S.W. 
Nov.  23,  1888.     Flood,  W.  C. 

119,  Highbury  Hill,  N. 
Mar.  25,  1913.     Ford-Fone,  W.  Edwin 

146,  Palmers  Road,  New  Southgate. 
June  23,  1871.     Freeman,  H.  E. 

Walcot,  Limes  Avenue,  New  Southgate,  N . 
Dec.  16,  1898.     French,  Archibald  J. 

57,  Ermine  Road,  Lewisham,  S.E. 
Jan.  18,  1907.     Fuelling,  George  Ernest 

195,  High  Road,  Streatham,  S.W. 
Feb.  22,  1910.     Fuller,  Frederick  Charles 

9,  Goldington  Road,  Bedford. 


Xlll 
Date  of  Election. 

Nov.  21,  1902.     Fuller,  William 

24,  Coleford  Road,  Alma  Road,  Wands- 
worth,  S.W. 

May  15,  1903.     Gabb,  G.  H.,  F.C.S. 

83,  Cray  ford  Road,  Tufnell  Park,  N. 
Nov.  25,  1913.     Gamman,  Robt. 

13,  Park  Road,  High  Barnet. 
Feb.  27,  1912.     Gammon,  Geo.  Edwd. 

6,  Mackintosh  Place,  Roath,  Cardiff. 
Dec.  15,  1905.     Gardner,  Edward  Lewis 

1,  Craven  Road,  Harlesden,  N.W. 
Jan.  20,  1899.     Gardner,  William,  F.R.M.S. 

292,  Holloway  Road,  N . 
Dec.  16,  1904.     Garnett,  Theodore,  M.A.  Oxon 

South  Bank,  Grassendale,  Liverpool, 
Jan.  27,  1914.     Gee,  Harry  Arthur 

20,  Buckler sbury ,  B.C. 
Mar.  24,  1914.     Gingell,  Leonard  Ralph 

10,  Moring  Road,  Tooting,  S.W. 
May  17,  1901.     Gladding,  Harold 
Nov.  22,  1910.     Gladstone,  Reginald  J.,  M.D. 

22,  Regent's  Park  Terrace,  N.W. 
Mar.  22,  1910.     Gonville,  Cyril  H.  K. 

"  Milton,"  Queen's  Road,  Buckhurst  Hill? 
N. 
Feb.  24,  1914.     Gooding,  Alfred  Charles 

53,  Park  Road,  Battersea,  S.W. 
Dec.  28,  1909.     Gooding,  Henry  Cornish 

Stowmarket,  Suffolk. 
April    2,  1909.     Gordon,  Fred  William,  F.R.M.S. 

"  Graylands,"  Augustus  Road,    Wimble- 
don Park,  S.W. 
Feb.  22,  1910.     Gordon,  John  WT. 

113,    Broadhurst    Gardens,    Hampstead, 
N.  W. 
Nov.  15,  1907.     Gray,  W. 

23,  Ramsden  Road,  Balham,  S.W. 
Jan.  25,  1910.     Green,  Frederick  N. 

40,  Lombard  Street,  E.C. 


XIV 

Date  of  Election. 

Jan.  16,  1903.     Green,  H.  0. 

4,  Leamington  Gardens,  Seven  Kings. 
Nov.  18,  1898.     Grocock,  L.  0. 
May  24,  1910.     Grundy,  James,  F.R.M.S. 

"  Ruislip"    Teignmouih    Road,    Crickle- 
wood,  N.W. 
June  25,-  1912.     Gurney,  Joseph 

Doivns  Farm,  Pinner  S.O.,  Middlesex. 
Feb.  19,  1904.     Gurney,  Robert 

Ingham  Old  Hall,  Stalham,  Norfolk. 
Nov.  28,  1911.     Guye,  Dr.  Paul 

12,    Rue  de   Candolle,   Geneva,   Switzer- 
land. 

Feb.  25,  1913.     Hall,  Rd. 

4,  Inglewood  Mansions,  West  End  Lane, 
Hampstead,  N.W. 
Sept.  28,  1888.     Hall,  T.  F. 

45,  Princes  Gate,  S.W. 
Feb.  22,  1910.     Hammond,  Alfred  Gauntlett 

101,  Melody  Road,  Wandsworth,  S.W. 
Jan.  25,  1910.     Hammond,  Arthur  Rashdall 

15,  Genoa  Road,  Anerley,  S.E. 
April  26,  1910.     Hammond,  Leonard  Frank 

22,  Mercers  Road,  N. 
Oct.  22,  1886.     Hampton,  W. 

The  Manor  House,  Weston,  Staffordshire. 
Nov.  26,  1912.     Hardman,  Wm,  J.P. 

"  Fernleigh,"  Bispham,  near  Blackpool. 
Nov.  22,  1910.     Harris,  A.  Wellesley,  M.R.C.S.,  etc. 

"  Alnwick,"  Berlin  Road,  Caiford,  S.E. 
May  19,  1905.     Harris,    Charles    Poulet,    M.I).,     M.R.C.S., 

L.R.C.P.,  F.R.M.S. 

98,  Lower  Addiscombe  Road,  Croydon. 
Jan.  27,  1914.     Harris,  Leslie  Edwin 

19,  Cheriton  Square,  Balham,  S.W. 
Dec.  21.  1906.     Hasslacher,  Charles  John 

3,  Kensington  Park  Gardens,  W. 
Mar.  28,  1879.     Hawkins,  C.  E. 

23,  Dalebury  Road,  Upper  Tooting,  S.W . 


Date  of  Election. 


Nov.  26,  1912.     Hayward,  Leslie  Chas. 

68,  Queens  Road,  Bay  stealer,  W. 
Feb.  15,  1901.     Headley,  F.  W. 

Haileybury  College,  Hertford. 
Jan.  19,  1906.     Heath,  Charles  Emanuel,  F.R.M.S. 

178,  Loughboro'  Road,  Brixton,  S.W. 
Feb.     5,  1909.     Hebdon,  William 

181,  Breakspears  Road,  Brockley,  S.E. 
April  20,  1906.     Herbert,  Robert  Henry 

32,  Fairmead  Road,  Holloway,  N. 

Feb.  21,  1908.     Heron-Allen,      Edward,      F.L.S.,      F.G.S., 

F.R.M.S.,  F.R.Met.S.,  F.Z.S. 

33,  Hamilton  Terrace,  N.W.,  and  Large 
Acres,  Selsey  Bill,  Sussex. 

Dec.  20,  1901.     Hicks,  Frederick  H. 

8,  Belmont  Road,  Wallington,  Surrey. 
Dec.  22,  1910.     Higginson,  George  Neale 

42,   Bartholomew  Road,    Camden    Town, 
N.W. 
Feb.  17,  1899.     Hill,  Edward  J. 

Darnlee,  Melrose,  N.B. 
Nov.  26,  1912.     Hill,  Wm,  F.G.S. 

"  The  Maples"  Hitchin. 
Nov.  15,  1895.     Hilton,  A.  E. 

1,    Highwood    Avenue,    North    Finchley, 
N. 
May  15,  1908.     Hiscott,  Thomas  Henry,  F.R.M.S. 

16,  Vioodville  Road,  Ealing,  W. 
May  27,  1913.     Hoare,  Stanley 

"  Baronscourt,"     The    Bishops    Avenue, 
N. 
Nov.  16,  1906.     Hocking,  William  John 

Royal  Mint,  E. 
Dec.  15,  1893.     Holder,  J.  T. 

114,  Pepys  Road,  Nevj  Cross,  S.E. 
Feb.  26,  1875.     Holford,  Christopher 

5,  Northumberland  Avenue,  Upper  Rich- 
mond Road,  Putney,  S.W. 
Dec.  20,  1907.     Holmes,  Frederick 

217,  Franciscan  Road,  Tooting,  S.W. 


XVI 

Date  of  Election. 


June  25,  1912.     Hook,  Gerald  Francis 

9,  Barrowgate  Road,  Chiswick,  W. 
May  27,  1913.     Hook,  Reginald  Vincent 

9,  Barrowgate  Road,  Chiswick,   W. 
Jan.  15,  1904.     Hopkinson,  John,  F.L.S.,  F.G.S.,  F.R.M.S. 

Weetwood,  Watford. 
Oct.  26,  1866.     Horncastle,  Henry 

'  Lindisaye,"  Woodham  Road,  Woking. 
April  15,  1898.     Hounsome,  John 

21,    Edith    Road,    Plashet    Grove,    East 
Ham,  E. 
Dec.     4,  1908.     Howard,  George 

Sitwell  Vale,  Moorgate,  Rotherham,  Yorks. 
Oct.  19,  1894.     Howard,  R.  N.,  M.R.C.S.,  F.R.M.S. 

The    Cape    Copper    Co.,    Ookiep,    Port 
Nolloth,   Namaqualand,   Cape  Colony, 
South  Africa. 
June  25,  1912.     Ho  worth,  Geo.  Franklin  Wise 

55,  Grovelands  Road,  Palmer's  Green,  N. 
Oct.  19,  1894.     Hughes,  F. 

Wallfield,  Reigate. 
May  28,  1886.     Hughes,  W. 

32,  Heathland  Road,  Stoke  Newington,  N. 
Nov.  23,  1909.     Huish,  Charles  Henry,  F.R.M.S. 

23,  Champion  Grove,  Grove  Lane,  S.E. 
June    4,  1909.     Hunter,  John  E. 

"  Strathblane,"  Park  Road,  Wallington. 
Dec.  20,  1901.     Hurrell,  Harry  Edward 

25,  Regent  Street,  Great  Yarmouth. 
Feb.  25,  1913.     Hutchin,  Chas.  Duncan 

c/o  Meredith  &  Drew,  Ltd.,  High  Street, 
Shadwell,  E. 

May  24,  1867.     Ingpen,  J.  E.,  F.R.M.S. 

21,  Wrotham  Road,  Broadstairs. 
Feb.  16,  1906.     Inwards,  Richard,  F.R.A.S. 

6,  Croftdown  Road,  Highgate  Road,  N.  W. 
Feb.  28,  1911.     Jacob,  Hugh  Frederick  Dawson,  M.I.E.E. 

c/o  Jessop  &  Co.,  Ltd.,  93,  Clive  Street, 
Calcutta. 


XV11 


Date  of  Election. 


Feb.  27,  1912.     Jacobs,  Reginald 

24,  Glenmore  Road,  Belsize  Park,  N.W. 
April  26,  1910.     Jervis,  Rev.  Edward  S. 

St.  Peter's  Vicarage,  Streatham,  S.W. 
Nov.  22,  1910.     Jewell,  Henry 

152,  Leathwaite  Road,  Clapham  Common, 
S.W. 
Nov.  17,  1905.     Jones,  Arthur  Morley 

11,  Eaton  Rise,  Ealing,  W. 
April  26,  1910.     Jones,  George  Fisher 

Devonshire    House,   Osterley  Park  Road, 
Southall,  W. 
Jan.  18,  1907.     Jones,  Rev.  Robert  Francis 

28,  Douglas  Road,  Canonbury,N. 
Feb.  22,  1910.     Jones,  William  Llewellyn 

Manley  Knoll,  Helsby,  Cheshire. 
Feb.  22,  1910.     Joshua,  Edward  Cecil 

St.   James's   Buildings,    William  Street, 
Melbourne,  Victoria. 


Nov.  17,  1905.     Karleese,  Benjamin 

The  Dell,  Barnt  Green,  Worcestershire. 
May  23,  1873.     Karop,  G.  C,  M.R.C.S.,  F.R.M.S.,  etc. 

Inniscorig,  Belting e  Road,  Heme  Bay. 
Feb.  25,  1913.     Kaufmann,  James  C,  LL.D. 

49,  Queen  Street,  Melbourne. 
June  21,  1907.     Kemp,  Francis  H.  N.  C. 

15,  Vernon  Road,  Homsey,  N. 
July  25,  1884.     Kern,  J.  J. 

63,  Queens  Road,  Beckenham,  Kent. 
Nov.  18,  1904.     Kew,  H.  Wallis 

3,  Hemdon  Road,  Wandsworth,  S.W. 
May  17,  1901.     Kirkman,  Hon.  Thomas,  M.L.C.,  F.R.M.S. 

Croftlands,  Esperanza,  Natal. 
May  19,  1905.     Kitchin,  Joseph,  FJl.M.S. 

"  Ingleneuk,"  14,  Brackley  Road,  Becken- 
ham, Kent. 
Mar.  22,  1889.     Klein,  S.  T.,  F.R.A.S.,  F.L.S.,  F.R.M.S. 

"  Hatherloiv,"  Raglan  Road,  Reigate. 
b 


XV111 
Date  of  Election. 

Dec.  28,  1909.     Knox,  Sydney  W. 

61,  Cambridge  Street,  Hyde  Park,   W. 
Mar.  24,  1914.     Koch  Victor,  M.E. 

43,  Elgin  Avenue,  Maida  Vale,  W. 

Feb.  17,  1905.     Lambert,  Charles  Alexander 

Bank   of   New   South    Wales,    Waricick, 
Queensland. 
Jan.  18,  1907.     Larkin,  Thomas  Gaisford 

29,  Thornlaw  Road,  West  Norwood,  S.E. 
Feb.  27,  1912.     Laverach,  Clyvie  Cordukes 

Br  ought  on  Rise,  Malton,   Yorks. 
June  17,  1904.     Lawrence,  Frederick  George 

c/o  Lionel  Samson  &  Son,  Cliff  Street, 
Fremantle,  West  Australia. 
Feb.  25,  1913.     Lawrence,  Harry  John 

7,  Norman  Road,  South  Wimbledon,  S.W. 
April  26,  1910.     Lawrence,  William  John 

21,  Cambridge  Road,  Lee,  S.E. 
Mar.  16,  1900.     Lawson,  Peter 

"  Jesmond,"  Nella  Road,  Fulham  Palace 
Road,  S.W. 
Jan.     1,  1909.     Leadbeater,  Herbert  C. 

81,  Elborough  Street,  Southfields,  S.W. 
Jan.  20,  1905.     Lees,  Rev.  Frederick  Clare, 

45,  Cavendish  Road,  Sutton,  Surrey. 
Nov.  21,  1902.     Leonard,  Edward 

14,  Fairview  Road,  Oxton,  Birkenhead. 
Nov.  17,  1905.     Levett,  Rev.  Robert  Kennedy,  F.R.M.S. 

The    Junior    School,    Bradfield    College, 
Reading,  Berks. 
Jan.  17,  1908.     Levin,  Arthur  Everard 

"  The  Croft;'  Bickley,  Kent. 
Feb.  22,  1910.     Lewis,  Frederic  Henry 

"  Ashmore,"    King's    Avenue,    Clapham 
Park,  S.W. 
April  27,  1866.     Lewis,  R,  T.,  F.R.M.S.  {Hon.  Reporter) 

41,  The  Park,  Ealing,  W. 
Nov.  25,  1913.     Liddon,  Capt,  Matthew  Robert 

12,  Kensington  Court,  W. 


XIX 

Date  of  Election. 


June  26,  1868.     Lindley,  W.  H.,  jun. 

29,BlittersdorffsPlatz,Frankfort-on-Main. 

Mar.  24,  1914.     Lloyd,  Francis  Wm.  y 

85,  Gracechurch  Street,  E.G. 

Dec.  23,  1913.     Lock,  Thos.  Benjn. 

78,  Riggindale  Road,  Streatham,  S.W. 

Jan.  18,  1907.     Lyon,  Massey,  F.R.M.S. 

c/o  Messrs.  Coutts,  440,  Strand,  W.C. 


May  25,  1883.     Mainland,  G.  E.,  F.R.M.S. 

14,  The  Norton,  Tenby,  South  Wales. 
Nov.  26,  1912.     Mardon,  Daniel  Arthur 

"  Emscote,"  Bishops  Stortford. 
June  17,  1898.     Marks,  Kaufmann  J.,  F.R.M.S. 

4,    Woodchurch  Road,   West  Hampstead, 
N.  W. 
Jan.  24,  1911.     Marsh,  George  Robertson,  M.A. 

Mallards    Close,    Twyford,    near    Win- 
chester, Hants. 
Feb.  15,  1895.     Marshall,  William  John,  F.R.M.S. 

20,  Emlyn  Road,  Shepherd's  Bush,  W . 
May  18,  1906.     Martin,  William 

"  Kethlen,"  Burgh  Heath,  Epsom,  Surrey. 
Nov.  28,  1911.     Martin,  Wm.  Julius 

55,  Breakspears  Road,  Brockley,  S.E. 
Nov.  18,  1898.     Massee,  G.,  F.L.S. 

Royal  Gardens,  Kew. 
Jan.  28,  1913.     Mavor,  Hilary 

"  Rookivood,"  Ingatestone,  Essex. 
Jan.  15,  1892.     Maw,  W.  H.,  F.R.M.S.,  F.R.A.S. 

18,  Addison  Road,  Kensington,  W . 
Mar.  28,  1911.     Maxwell,  Edward  Kelly,  B.A. 

H.M.  Patent  Office,  W.C. 
April  23,  1912.     Mead,  Arthur 
May  19,  1893.     Merlin,  A.  A.  C.  Eliot,  F.R.M.S. 

British  Consulate,  Volo,  Greece. 
Oct.  18,  1907.     Mestayer,  Richard  L.,  M.I.C.E.,  F.R.M.S. 

Lambton   Quay,     Wellington,   New    Zea- 
land. 


XX 

Date  of  Election. 


Mar.  26,  1912.     Metealf,  John 

St.  Bede's,  Hermon  Hill,  Woodford,  E. 
July  27,  1877.     Michael,  A.  D.,  F.L.S.,  F.Z.S.,  F.R.M.S. 

The   Warren,  Studland,   near   Wareham, 
Dorset. 
July    7,  1865.     Millett,  F.  W.,  F.G.S.,  F.R.M.S. 

Eniscoe,  Brixham,  Devon. 
Feb.  25,  1913.     Mills,  Fdk.  Wm,  F.R.M.S. 

Thornleigh  Edgerton,  Huddersfield. 
Jan.  20,  1905.     Milne,  William 

Uitenhage,  Cape  Colony,  South  Africa. 
Oct.  18,  1907.     Minchin,  Edward  Alfred,  M.A.,  Ph.D.,  F.R.S., 

(Vice-President) 

53,  Cheyne  Court,  Royal  Hospital  Road, 
Chelsea,  S.W. 
Oct.  18,  1901.     Moore,  Harry,  F.R.M.S. 

12,  Whiston  Grove,  Moorgate,  RotJierham, 
Yorks. 
July  26,  1878.     Morland,  Henry 

Cranford,  near  Hounslow. 
Oct.  25,  1910.     Morris,  Charles  Barham 

Waitaki  Pharmacy,   Thames  Street,  Oa~ 
maru,  N.Z. 
June  25,  1912.     Morris,  Jesse  Crawford 

Harrisville,  Harrison  County, Ohio,  U.S.A. 
June    4,  1909.     Mortimer,  Hugh  Hamilton 

20,  Birchin  Lane,  E.C. 
Jan.  16,  1891.     Muiron,  C. 

49,  Chatsworth  Road,  Brondesbury,  N.W. 
Dec.  23,  1913.     Mumford,  Frank  Septimus 

Belmont,  Doncaster.        * 
Nov.  22,  1910.     Mummery,  J.  Howard,  M.R.C.S. 

Islips  Manor,  Northolt,  Middlesex. 
June  16,  1905.     Myles,  James  Cellars 

53,  Carlyle  Road,  Manor  Park,  S.  Essex. 

Jan.  27,  1914.     Nail,  Rev.  Geo.  Herbert 

18,  Deans  Yard,  Westminster,  S.W. 
Mar.  24,  1876.     Nelson,  E.  M.,  F.R.M.S. 

Beckington,  Bath. 


XXI 

Date  of  Election. 


May  16,  1902.     Nevill,  Rev.  T.  J.,  F.R.M.S. 

2,  Grange  Road,  Eastbourne. 
Feb.  15,  1907.     Newman,  Charles  Arnold 

Oundle,  Northants. 
May  27,  1913.     Newniarch,  Edgar  Ribton 

4,  The  Drive,  Walthamstow,  N.E. 
Jan.  26,  1872.     Newton,  E.  T.,  F.R.S.,  F.G.S. 

Florence  House,  13,  Willow  Bridge  Road, 
Canonbury,  N. 
Jan.  17,  1908.     Nicholson,  Alfred 

7,  Belton  Road,  Sidcup. 
Dec.  23,  1913.     North,  Jas.  Herbert 

11,       Parliament       Hill,      Hampstead, 
N.W. 
Nov.  28,  1911.     Nutt,  Hy.  Francis 

51,  Gurdon  Road,  Charlton,  S.E. 


Feb.  25,  1913.     Oatley,  Wm. 

Badcox,  Frome 
Feb.  16,  1900.     O'Donohoe,  T.  A. 

8,  Myrtle  Road,  Acton,  W. 
Jan.  24,  1879.     Offord,  J.  M.,  F.R.M.S. 

3,  Cleveland  Gardens,  West  Ealing,  W. 
Dec.  22,  1876.     Ogilvy,  C.  P.,  F.L.S. 

Sizewell  House,  Leiston,  near  Saxmund- 
ham,  Suffolk. 
May  17,  1907.     Ogilvy,  J.  Wilson,  F.R.M.S. 

18,  Bloomsbury  Square,   W.C. 
Nov.  15,  1907.     Oke,  Alfred  William,  B.A.,  LL.M. 

32,  Denmark  Villas,  Hove. 
Nov.  18,  1892.     Orfeur,  Frank,  F.R.M.S. 

91,  Effra  Road,  Brixton,  S.W. 
April  23,  1912.     Owen,  Wm.  Hy. 

19,  Home  Park  Road,   Wimbledon. 
Dec.  27,  1867.     Oxley,  Frederick,  F.R.M.S. 

c/o  A.   E.   Linton,   Esq.,   Box  9,   P.O., 
Nairobi,  British  East  Africa, 
Dec.  18,  1903.     Oxley,  F.  J.,  M.R.C.S. 

1,  Dock  Street,  E. 


XX11 
Date  of  Election. 


Feb.  27,  1912.     Palmer,  Hy.,  J.P.,  F.R.G.S. 

Monks    Holme,    Corbridge-on-Tyne. 
Nov.  25,  1913.     Panichelli,  Frank 

7,  Rowan  Road,  Hammersmith,  W. 
April  10,  1910.     Parfitt,  Edward  William 

7,  Gatcombe  Road,  Tujnell  Park,  N. 
Feb.  25,  1913.     Parrott,  Fdk.  Wm. 

The  Downs,  Bowden,  Cheshire. 
Oct.  27,  1871.     Parsons,  F.  A.,  F.R.M.S. 

15,  Osborne  Road  Finsbury  Park,  N. 
Dec.  16,  1904.     Patterson,  George 

20,    Madrid    Road,    Castlenau,    Barnes, 
S.W. 
July  23,  1886.     Paul,  R. 

"  Holmbush"    Cyprus   Road,    Exmouth,. 
Devon. 
Jan.  18,  1901.     Paulson,  Robert,  F.L.S.,  F.R.M.S. 

"  Glenroy,"  Cecil  Park,  Pinner,  Middle- 
sex. 
May  24,  1867.     Pearson,  John 

40,  Maida  Vale,  W. 
May  23,  1911.     Pells,  Cyril  E., 
May  20,  1904.     Perks,  Frederick  John  (Hon.  Treasurer) 

48,  Grove  Park,  Denmark  Hill,  S.E. 
Jan.  18,  1907.     Perry,  Francis  Gough 

2,  The  Cloisters,  Gordon  Square,  W.C. 
Mar.  17,  1905.     Phipps,  William  Joseph 

132,  Pinner  Road,  Oxhey,  Herts. 
Feb.  20,  1903.     Pilcher,  Charles  Frederick 
Nov.  15,  1895.     Pillischer,  J.,  F.R.M.S. 

88,  New  Bond  Street,  W. 
April  25,  1910.     Pinchin,  Ernest  Alfred,  B.Sc, 

4,  Gleneldon  Road,  Streatham,  S.W. 
Nov.  26,  1912.     Pitt,  Edward 

Madeley  Ho.,  Gerrard's  Cross,  Bucks. 
Nov.  19,  1897.     Pittock,  George  Mayris,  M.B.,  F.R.M.S. 

Winton,  Whitstable  Road,  Canterbury. 
Jan.  15,  1904.     Pledge,  John  H.,  F.R.M.S.  {Hon.  Assistant 

Secretary) 

72,  Nibthwaite  Road,  Harrow. 


XX111 
Date  of  Election. 


Nov.  23,  1883.     Plowman,  T. 

Nystuen  Lodge,  Bycullah  Park,  Enfield. 
Sept.  21,  1894.     Pollard,  Jonathan,  F.R.M.S. 

10,  Porteus  Road,  Paddington  Green,  W. 
May  18,  1900.     Poser,  M.,  F.R.M.S. 

37-38,  Hatton  Garden,  E.C. 
June  21,  1895.     Poulter,  Christopher  S. 

Mount   Lodge,  Parkhurst  Road,  Bexley, 
Kent. 
Feb.  17,  1899.     Powell,  Arthur 

28,  Stafford  Terrace,  Kensington,  W. 
May  17,  1901.     Powell,  David,  M.A.,  F.R.M.S. 

Over  strand,  Grove  Park  Road, Chiswick,  W. 
July     7,  1865.     Powell,  Thomas  H.,  F.R.M.S. 

Emsdale,  Greenham  Road,  Muswell  Hill, 
N. 
Dec.  20,  1907.     Pratt,  John  Edwin 

6,  Heath  field  Terrace,  Seven  Kings,  Essex. 
June    4,  1909.     Pring,  S.  W. 

"  Sandhill, "    Avondale    Road,    Newport, 
Isle  of  Wight. 
Xov.  26,  1912.     Pulford,  Herbert,  M.A.,  etc. 

The  Winnats,  Lowestoft  Road,  Gorleston- 
on-Sea. 
Feb.  28,  1911.     Pullman,  John 

The  Knollsea,  Lilliput,  Dorset. 

Xov.    6,  1908.     Quick,  Albert  Hedley 

"  Inverness,"   Malvern  Road,    Thornton 
Heath. 

Jan.  18,  1901.     Radley,  Percy  E.,  F.R.M.S. 

30,  Foxgrove  Road,  Beckenham,  Kent. 
Xov.  25,  1913.     Ramsay,  Ernest  Wm. 

14,  Whiteley  Road,  Upper  Norwood,  S.E. 
April  22,  1913.     Rawson,  Col.   Herbert  Edward,  C.B. 

Home  Close,  Heronsgate,  Herts. 
Xov.  16,  1906.     Reid,  Duncan  J.,  M.B.,  CM. 

20,  Blakesley  Avenue,  Ealing. 
Mar.  20,  1896.     Rheinberg,  Julius,  F.R.M.S. 

23,  The  Avenue,  Brondesbury  Park,  N.W. 


XXIV 


Date  of  Election. 


Sept.  18,  1891.     Richards,  F.  W. 

212,  Notre  Dame  Street  West,  Montreal, 
Canada. 
Oct.     2,  1908.     Richards,  William 

3,  Favart  Road,  Fulham,  8.  W. 
Jan.  18,  1901.     Richardson,  John 

28,  Beaumont  Avenue,  Richmond,  Surrey. 
Nov.    6,  1908.     Rink,  Max 

9,  Cannon  Place,  Christchurch,  H amp- 
stead,  N.W. 
June  21,  1901.     Robertson,  Sir  Helenus  R.,  F.R.M.S. 

Upton  Grange,  Chester. 
Mar.  15,  1907.     Robertson,  James  Alexander,  F.R.M.S. 

Lune  View,  Fleetwood. 
April  28, 1914.     Robotham  Fras.  Edward 

48,  Lillieshall  Road,  Clapham,  S.W. 
JNov.  16,  1900.     Rogers,  G.  H.  J.,  F.R.M.S. 

55,  King  Street,  Maidstone. 
June    4,  1909.     Rolph,  Frank 

Harts  Stables,  Woodford  Green,  E. 
Jan.  25,  1884.     Rosseter,  T.  B.,  F.R.M.S. 

East  Kent  Club,  Canterbury. 
Jan.  26,  1883.     Rousselet,    Charles   F.    (Vice-President   and 

Hon.  Secretary  for  Foreign  Correspondence) , 
Curator  R.M.S. 

Fir  Island,  Mill  Hill,  N.W. 
Nov.  26,  1912.     Row,  Rd.  Wm.  Harold 

36,  Lexham  Gardens,  Kensington,  S.  W. 
Nov.  18,  1904.     Rowley,  Frederick  Richard,  F.R.M.S. 

8,  Pinhoe  Road,  Heavitree,  Exeter. 
April  27,  1888.     Russell,  J. 

16,  Blacket  Place,  Newington,  Edinburgh. 
Jan.  23,  1912.     Ryan,  Ernest  K.  W. 

5,  Rossdale  Road,  Putney,  S.W. 

Mar.  24,  1914.     St.  George,  Harry  A. 

112,  Albany  Street,  Regent's  Park,  N.W. 
Nov.  21,  1902.     Sanderson,  R.  Z. 

26,  Baronsfield  Road,  St.  Margaret's,  E, 
Twickenham,  Middlesex. 


XXV 

Date  ol  Election. 


Dec.  23,  1913.     Saunders,  Reginald  Arthur 

10,  Regent's  Park  Road,  N.W. 
April  2,  1909.     Saxton,  Thomas  R.,  A.M.I.C.E.,  F.R.M.S. 

43,  East  Bank,  Stamford  Hill,  N. 
Xov.  28,  1911.     Schmerl,  Augustus 

34,     St.     Gabriel's     Road,     Cricklewood, 
N.W. 
June  20,  1890.     Scourfield,   D.   J.,   F.Z.S.,   F.R.M.S.    {Vice- 
President) 

63,  Queen's  Road,  Leytonstone,  E. 
May  20,  1898.     Sears,  Robert  S.  W.  - 

1,  Lisson  Grove,  N.W. 
Jan.  27,  1914.     Shelley,  G.  H. 

51,  Champion  Grove,  Denmark  Hill,  S.E. 
Xov.  25,  1913.     Shepherd,  Benjamin 

Fir  Cottage,  Oak  Lane,  Bounds  Green,  N. 
Dec.  28,  1909.     Shephard,  John 

Clark  Street,  South  Melbourne,  Victoria. 
May  26,  1876.     Shepheard,  Thomas,  F.R.M.S. 

Kingsley,  Bournemouth  West. 
June  21,  1907.     Sheppard,  Alfred  William,  F.Z.S.,  F.R.M.S, 

{Hon.  Editor) 

1,  Vernon  Chambers,  W.C. 
Jan.  28,  1913.     Sheppard,  Eclwd.  Jas.,  F.R.M.S. 

137,  Kenninglon  Road,  S.E. 
Mar.  25,  1913.     Shuckard,  David  Hy. 

14,  Walerand  Road,  Leivisham,  S.E. 
Feb.  28,  1911.     Sidebottom,  Henry 

"  Woodstock,''    Syddal    Park,  BramhaU, 
Cheshire. 
June  19,  1896.     Sidwell,    Clarence    J.    H.,    F.R.M.S.    {Hon. 

Curator) 
46,  Ashbourne  Grove,  Duhvich,  S.E. 
Feb.  22,  1910.     Simpson,  Norman  Douglas 

Carlton      Mincott       Vicarage,      Thirsk, 
Yorks. 
Oct.  26,  1903.     Skorikow,  Alexander  Stepanovic 

Musee  Zoologique  de  VAcademie  lin- 
periale  des  Sciences,  St.  Petersburg, 
Russia. 


XXVI 

Date  of  Election. 


Oct.  21,  1904.     Smith,  Arthur  Edgar 

"  Helios,"  71,  Fox  Lane,  Palmer's  Green, 
N. 
Mar.  25,  1870.     Smith,  F.  L. 

3,  Grecian  Cottages,  Crown  Hill,  Norwood, 
S.E. 
Mar.  17,  1899.     Smith,  Frank  P. 

2,  King's  Villas,  Chase  Road,  Southgate. 
Mar.  17,  1905.     Smith,  Frederick 

13,  Rye  Hill  Park,  Peckham  Rye,  S.E. 
Nov.  18,  1898.     Smith,  Thomas  J.,  F.R.M.S. 

c/o  W.  Watson  &  Sons,  313,  High  Hol~ 
born,  W.C. 
Jan.  15,  1892.     Soar,  C.  D.,  F.L.S.,  F.R.M.S. 

37,  Dryburgh  Road,  Putney,  S.W. 
April  21,  1899.     Spitta,    Edmund    J.,    L.R.C.P.,    M.R.C.S., 

F.R.A.S.,  F.R.M.S.  {Vice-President) 

41,   Ventnor  Villas,  Hove,  Brighton. 
April  21,  1899.     Spitta,     Harold     R,    D.,    M.D.,    M.R.C.S., 

D.R.C.P.,  D.P.H. 

12,  Bolton  Street,  May  fair,  W. 
Jan.  15,  1904.     Sprague,  T.  B.,  LL.D. 

29,  Buckingham  Terrace,  Edinburgh. 
Dec.  23,  1913.     Sprenger,  Hy.  Fdk.  Wm. 

64,  Hallam  Street,  Portland  Place,  W. 
Jan.  28,  1913.     Spry,  Lt.  Robt.,  R.N.,  F.R.M.S. 

83,  Mount  Gold  Road,  Plymouth. 
Jan.  18,  1907.     Stahl,  Arthur 

11,  Scotts  Avenue,  Shortlands,  Kent. 
Nov.  16,  1906.     Stephens,  Samuel  Phillips 

15,  Green  Street,  Kimberley,  Cape  Colony. 
Nov.  27,  1885.     Stevenson,  G.  T. 

Ravenscourt,  Haling   Park   Road,  South 
Croydon. 
June  18,  1897.     Still,  Arthur  L. 

Roslyn,  Dower  Avenue,    Wallington. 
Nov.  16,  1894.     Stokes,  William  B. 

212,  Notre  Dame  Street,  West  Montreal. 
Dec.  15,  1893.     Sturt,  Gerald 

'  Lismore,"  Cavendish  Road,  Weybridge. 


xxvn 

Date  of  Election. 


Dec.  17,  1875.     Swift,  M.  J.,  F.R.M.S. 

6,  Aylestone  Avenue,  Brondesbury,  N .W . 

Nov.  28,  1879.     Tasker,  J.  G. 

30,  Junction  Road,  Upper  Holloway,  N. 
Oct,  16,  1896.     Taverner,  Henry,  F.R.M.S. 

319,  Seven  Sisters  Road,  Finsbury  Park, 
N. 
May  24,  1910.     Taylor,  Charles  Ernest 

178,  Uxbridge  Road,  West  Ealing. 
Feb.  17,  1905.     Taylor,  Thomas  George 

Ballaclague,  Ellington  Park  Road,  Rams- 
gate. 
Dec.  22,  1865.     Terry,  John 

8,  Hopton  Road,  Coventry  Park,  Streat- 
ham,  S.W. 
Feb.  28,  1911.     Thomas,  Edwin  Harvey 
Mar.  26,  1912.     Tibbie,  Bertie  Wallace 

27,  St.  Paul's  Road,  Canonbury,  N. 
June  24,  1913.     Tierney,  Clarence  M.  S.,  F.R.M.S. 

10,  Enmore  Park,  Norwood,  S.E. 
May  16,  1902.     Tilling,  George,  F.R.M.S. 

"  Grasmere,"    Rydal    Road,    Streatham, 
S.W. 
Nov.  25,  1913.     Tilling,  Wm.  Geo. 

20,  Streathbourne  Road,   Upper  Tooting, 
S.W. 
Jan.  25,  1910.     Todd,  Charles  Stephen 

25,  Hanover  Road,  Tottenham,  N. 
Feb.  27,  1912.     Tomlinson,  Edwd.  Theodore 

8,  St.  George's  Square,  S.W. 
Nov.  26,  1912.     Tonkin,  Thos.  S. 

Bramley  Avenue,  Coulsdon,  Surrey. 
Dec.  21,  1894.     Traviss,  Will.  R, 

42,     Winchester    Avenue,     Brondesbury, 
I  N.  W. 

Feb.  25,  1913.     Trotman,  Alex.  Chas. 

28,  Gubyon  Avenue,  Heme  Hill,  S.E. 
Mar.    5,  1909.     Troughton,  Henry  George 

3,  New  Court,  Lincoln's  Inn,  W.C. 


XXV111 

Date  of  Election. 


May  15,  1903.     Tupman,  Lt.-Col.  G.  Lyon,  F.R.M.S. 

College  Road,  Harrow. 
June  17,  1892.     Turner,  C. 

20,  Minster  Road,  Crickleivood,  N.W. 
Feb.  25,  1913.     Tyas,  Rev.  Vetranio 

12,  Felstead  Road,  Wanstead,  N.E. 
June  21,  1901.     Tvrell,  E.  G.  Harcourt 

Park  Rynie,  Natal,  S.A. 

Mar.  16,  1906.     Vogeler,  Gustav 

17,  Philpot  Lane,  E.C. 

Jan.  24,  1914.     Walker,  Arthur 

306,  South  Lambeth  Road,  S.W. 
July  25,  1873.     Walker,  J.  S. 

6,  Warwick  Road,  Upper  Clapton,  N.E. 
Nov.  22,  1910.     Watts,  Geo.  W. 

103,  Haverstock  Hill.  N.W. 

Dec.  21,  1900.     Webster,  Rev.  T. 

June  16,  1899.     Wedeles,  James,  F.R.M.S. 

231,    Flinders    Lane,    Melbourne,    Aus- 
tralia. 
May  28,  1912.     Weiss,  Robt, 

7  &  8,  Idol  Lane,  E.C. 
Mar.  20,  1908.     West,  Joshua  Cobbett 

20,  Millbrook  Road,  Brixton,  S.  W. 
Feb.  25,  1876.     Wheeler,  George 

64,  Canonbury  Park  South,  N. 
Jan.  25,  1910.     Whitehead,  Henry,  B.Sc.  Lond. 

Wadham    House,    Toynbee    Hall,    Com- 
mercial Road,  E. 
Nov.  26,  1912.     Whitteron,  Fred. 

Geelong,  Victoria. 
Dec.     4,  1908.     Wilkins,  Thomas  Smith 

Eversley,  Uttoxeter. 
Nov.  23,  1877.     Williams,  G.  S. 

Tor  Hill,  King sker swell,  Devon.. 
Jan.  19,  1906.     Wilson,  Joseph,  F.R.M.S. 

Hillside,  Avon  Road,    Upper   Waliham 
stow,  Essex. 


XXIX 

Date  of  Election. 


Feb.  27,  1912.     Wood,  Fredk.  Geo. 

161,  Walworth  Road,  S.E. 
Dec.  20,  1895.     Wood,  Walter  J.,  F.R.M.S. 

"  Ernecroft,"  Abbey  Road,  Grimsby. 
Nov.  16,  1894.     Wooderson,  Edwin 

"  Konigsfeld,"     39,     Dartmouth    Road, 
Brondesbury,  N.W. 
Mar.  15,  1907.     Worssam,  Cecil 

17,   Grafton  Road,  Bedford. 
Jan.  18,  1907.     Wright,  Joseph  Pepper 

c'to   Messrs.   Davidson,  Boules,   Ld.,   86,. 
Wellington     Street,      West     Toronto, 
Canada. 
Feb.  21,  1902.     Wyatt,  Edward 

Gordonia,     Gloucester    Road,     Norbiton> 
Kingston. 
Jan.  18,  1901.     Wykes,  William 

7,  Plaistow  Park  Road,  Plaistow,  Essex. 

Mar.  24,  1914.     Yermoloff,  His  Excellency  Nicholas,  K.C.V.O. 

3,  Whitehall  Court,  S.W. 
Nov.  23,  1888.     Young,  G.  W.,  F.G.S. 

20,  Grange  Road,  Barnes,  S.W. 

Nov.  15,  1907.     Zehetmayr,  Walter  E. 

Belle  Vue,  St.  Margaret's,  Twickenham. 
Dec.  19,  1902.     Zimmerman,  Prof.  C,  F.R.M.S. 

Collegio,  Antonio  Viera,  Bahia,  Rua  do 
Sodre  43,  Brazil. 


NOTICE. 

Members  are  requested  to  give  early  information  to  the  Treasurer 
of  any  change  of  residence,  so  as  to  prevent  miscarriage  of  Journals 
and  Circulars. 


XXX 


List  of  Exchanges  and  of  Societies,  etc.,  which 

Receive  the  Journal. 


An    die    Redaktion    des     '  Mikrokosnios,"    Pfizerstrasse,    5, 

Stuttgart,  Germany. 
American  Microscopical  Society,  T.  W.  Galloway,  Secretary, 

Decatur,  111.,  U.S.A. 

Bausch  &  Lomb  Optical  Company,  Publication  Department, 
Rochester,  N.Y.,  U.S.A. 

Bergens  Museums  Bibliothek,  Bergen,  Norway. 

Birkbeck  College,  Bream's  Buildings,  Chancery  Lane,  W.C. 

Birmingham  Natural  History  and  Philosophical  Society, 
Norwich  Union  Chambers,  Congreve  Street,  Birmingham. 

Botanical  Society  of  Edinburgh  (The  Curator),  The  Botanic 
Gardens,  Edinburgh. 

Botanisches  Centralblatt,  c/o  Dr.  J.  P.  Lotsy,  Spaarne  17, 
Haarlem,  Holland. 

Brighton  and  Hove  Natural  History  Society,  c/o  The  Public- 
Library,  Brighton. 

Bristol  Naturalists'  Society  (The  Librarian),  5,  Lansdown 
Place,  Clifton,  Bristol. 

British  Association  for  the  Advancement  of  Science,  Burling- 
ton House,  London,  W. 

■ 

Canadian  Institute,  W.  H.  Vandersmitten,  Esq.,  Secretary, 
46,  Richmond  Street  East,  Toronto,  Canada. 

Concilium  Bibliographicum,  Zurich -Neumunster,  Switzerland. 

Croydon  Natural  History  and  Scientific  Society  (The  Secre- 
tary), Public  Hall,  Croydon. 


XXX 1 


Dohrn,  Prof.  Reinhart,  The  Zoological  Station,  Naples. 

"  English  Mechanic,"  5,  Effingham  House,  Arundel  Street, 

W.C. 
Entomological  Society,  11,  Chandos  Street,  Cavendish  Square, 

W. 
Essex  Field  Club,  Essex  Museum  of  Natural  History,  Stratford, 

Essex. 

Geologists'  Association  (The  Librarian),  University  College, 
Gower  Street,  W.C. 

Herts  Natural  History  Society,  c/o  Daniel  Hill,  Esq.,  "  Herga," 

Watford,  Herts. 
Historical   and   Scientific    Society    of    Manitoba,    Winnipeg, 

Canada. 
Horniman  Museum,  Forest  Hill,  S.E.  (The  Curator). 
Hull  Scientific  and  Field  Naturalists'  Club,  Royal  Institution, 

Hull. 

Illinois  State  Laboratory  of  Natural  History  (Library), 
Urbana,  111.,  U.S.A. 

Imperial  Leopold-Caroline  Academy,  Halle-an-der-Saale,  Ger- 
many. 


a 


Knowledge,"    The    Knowledge    Publishing   Co.,    Ltd.,    42, 
Bloomsbury  Square,  W.C. 


Leicester  Literary  and  Philosophical  Society,  Dr.  Strace}7, 
Hon.  Librarian,  Priory  Lodge,  New  Walk,  Leicester. 

Library,  Bureau  of  Science,  Manila,  Philippines. 

Linnean  Society,  Burlington  House,  Piccadilly,  W. 

Literary  and  Philosophical  Society  of  Manchester  (The 
Librarian),  36,  George  Street,  Manchester. 

Lloyd  Library,  Cincinnati,  Ohio,  U.S.A. 

Manchester  Microscopical  Society,  J.  E.  Storey,  Esq.,  2C, 
Grosvenor  Road,  Whalley  Range,  Manchester. 

Microscopical  Society  of  Liverpool,  Royal  Institution,  Colquitt 
Street,  Liverpool. 


XXX11 


Missouri  Botanical  Garden,  St.  Louis,  Mo.,  U.S.A. 

Natural  History  Society  of  Northumberland,  Durham,  and 

Newcastle-upon-Tyne  (The  Librarian),  Hancock  Museum, 

Barras  Bridge,  Newcastle-upon-Tyne. 
Natural    History    Branch     of    the    British    Museum    (The 

Librarian),  South  Kensington,  W. 
Natural  History  Society  of  Glasgow   (The  Librarian),  207, 

Bath  Street,  Glasgow. 
V  Nature  "  (The  Editor),  St.  Martin's  Street,  W.C. 
Netherlands  Zoological  Society,  Zoological  Station,  Helder, 

Holland. 
"  Nuova  Notarisia,"  c/o  Prof.   G.   B.   De  Toni,  University 

Royale  de  Modena,  Modena,  Italy. 
"  Nyt  Magazin  for  Naturaidenskaberne,"  c/o  Prof.  Dr.  N. 

Wille,  Botan.  Garten,  Christiania. 

Oberhessische  Gesellschaft  fur  Natur-  und  Heilkunde,  Giessen, 

Germany. 
Optical  Society  (The  Hon.  Librarian),  39,  Victoria  Street,  S.W. 

Patent  Office  Library,  25,  Southampton  Buildings,  Chancery 

Lane,  W.C. 
Philadelphia  Academy  of  Natural  Sciences,  Philadelphia,  Pa., 

U.S.A. 
Philippine    Exposition    Board,    Calle    General    Solano    384, 

Manila,  Philippine  Islands. 

R.  Scuola  Superiore  di  Agricoltura,  Portici,  Italy. 
Roj^al  Dublin  Society,  Leinster  House,  Dublin. 
Royal  Institute  of  Cornwall,  Truro. 
Royal  Institution,  21,  Albemarle  Street,  W. 
Royal  Society  of  Medicine,  1,  Wimpole  Street,  W. 
Royal  Microscopical  Society,  20,  Hanover  Square,  W. 
Royal  Society,  Burlington  House,  Piccadilly,  W. 
Royal  Society  of  New  South  Wales,  Sydney. 
Royal  Society  of  Arts,.  John  Street,  Adelphi,  W.C. 

Saunders,  Sibert,  Esq.,   197,  Amesbury  Avenue,  Streatham 
Hill,  S.W. 


XXX111 

Smithsonian  Institution,  Washington,  D.C. 

Smithsonian  Institution   (United  States  National  Museum), 

c/o  Win.  Wesley  &  Son,  28,  Essex  Street,  Strand. 
Societe  Beige  de  Microscopie,  c/o  Mons.  A.  Castaigne,  28,  Rue 

de  Berlaimont,  Bruxelles. 
Societe  Botanique  Italienne,  Florence,  Italy. 

Tempere,  Mons.  J.,  Grez-sur-Loing,  par  Bourron,  Seine  et 
Marne. 

University   of   California    Library    (Exchange   Department), 
c/o    Wm.    Wesley    &    Son,    28,    Essex   Street,    Strand, 
London,  W.C. 

Victoria,  Australia,  Field  Naturalists'  Club  of,  A.  D.  Hardy. 
Hon.  Secretary, 

Wagner  Free  Institute,  Montgomery  Avenue  and  17th  Street, 

Philadelphia,  U.S.A. 
Wesenberg-Lund,  Dr.,  Slotsgade,  Hillerod,  Denmark. 
Wisconsin  Academy  of  Sciences,  Arts,  and  Letters  (Exchange 

Secretary),  Madison,  Wis.,  U.S.A. 

Zoologisch-botanische  Gesellschaft  in  Wien,  III.  3,  Mechel- 
gasse  Nr.  2,  WTien,  Austria. 


MBL  WHOI  LIBRARY 


UH 


fiXB    G